Twelfth Doctor

The Twelfth Doctor emerged from his predecessor's explosive regeneration on Trenzalore, being the product of "regeneration number thirteen." He was the first incarnation of the Doctor's second regeneration cycle, which had been bestowed upon him by the Time Lords. Clara Oswald, continuing her travels with him after he regenerated, served as his primary companion, and at times acted as his moral compass.

Assured of the survival of Gallifrey, he was no longer chained down by his guilt. A darker character with a withdrawn and spiky attitude, he was less amiable and habitually questioned his own goodness. Although this incarnation was no stranger to kindness and humour, he often dispensed with niceties in a tense situation, becoming cold and calculative in critical moments that required sound judgment and the occasional application of sharp practice.

However, because of his detachment from emotions, he could come off as unpleasant, fearsome, and ruthless. These qualities often terrified those who were around him, even his companions. He became harder to trust, and acknowledged his shift toward negative personality traits, feeling incensed and fearful at what he was changing into.

Unlike his predecessor's adventures with Clara, this Doctor found more strain was being placed on their relationship; Clara was dating fellow Coal Hill teacher Danny Pink, whom the Doctor mutually disliked.

Preparations
During a visit to a parallel universe where he was a fictional character in a television series, the Eleventh Doctor told his portrayer, Matt Smith, that Peter Capaldi, whom he had previously rescued from a Mandrel, would be a good choice to play him on the show. (COMIC: The Girl Who Loved Doctor Who)

Post-regeneration
After fighting in the Siege of Trenzalore for 900 years, (PROSE: Tales of Trenzalore: The Eleventh Doctor's Last Stand), the Eleventh Doctor, facing extermination from the Daleks in his old age, was ready to accept that he had reached the end of his final life. Unable to accept his death, Clara Oswald appealed to the Time Lords to intervene and the Doctor received a new regeneration cycle. After using the energy from the regenerative reset that followed to destroy the Dalek mother ship, the Doctor, still dying from old age returned to his TARDIS to undergo his thirteenth regeneration.

Suddenly changing in a flash before Clara's eyes, the new Doctor voiced his surprise at having new kidneys. The TARDIS then began shaking violently, and the Doctor implied to have forgotten how to pilot his ship, much to a shocked Clara's dismay. (TV: The Time of the Doctor) Crashing in pre-historic Earth, the TARDIS was chased and subsequently swallowed by a female Tyrannosaur; when the Doctor brought the TARDIS to 1890s London, the dinosaur was accidentally brought along with it.

After the TARDIS was spat out, the Doctor, in a severe bout of post-regenerative trauma, acted very wild and irrationally. He peeked out of the TARDIS door, shushed Strax, slammed the door shut momentarily, and then finally crept out of the TARDIS, trying to identify him as one of the Seven Dwarves. Unable to remember names or faces clearly, he sputtered at the sight of the Paternoster Gang, before being joined by a frazzled and annoyed Clara, trying to keep some degree of control on his livid and maddened state.

Though put to bed to stabilise, the Doctor soon awoke and, grabbing a piece of chalk, doodled all over the bedroom with strange equations. Hearing the dinosaur in pain, the Doctor climbed out onto the rooftop and left on horseback when he saw the T-Rex was being burned to ashes. Deciding to investigate, but still suffering a degree of post-regenerative stress, the Doctor wandered the streets of London. Talking to a passing tramp, the Doctor examined his new facial features, taking particular note of his new eyebrows, as well as his new Scottish accent, before trading in his previous incarnation's favourite watch for the tramp's coat. (TV: Deep Breath)

Seeing an ad in a newspaper placed by, (TV: Death in Heaven) that seemed to be a message from Clara, the Doctor infiltrated a suspicious restaurant, where he and Clara learned that time travelling Clockwork Droids, under the leadership of the Half-Face Man, had been harvesting humans to repair themselves and reach the Promised Land. Trying to speak on peaceful terms, the Doctor snapped the Control Node out of his illusion of the Promised Land by revealing the true state of his existence. Conflicted and unsure, the Half-Face Man fell out of his escape pod, either jumping or having been pushed by the Doctor. (TV: Deep Breath)

The Doctor briefly left Clara behind to help his previous incarnations place Gallifrey in a pocket universe at the end of the Last Great Time War (TV: The Day of the Doctor), setting up the events of his previous incarnation's long stand-off on Trenzalore. After this, the Doctor took the time to redecorate the TARDIS console room and settle on a new outfit. Returning for Clara, the Doctor spoke of the suspicious way Clara had met him in his previous incarnation, only for Clara to likewise voice her uncertainty of the Doctor's identity and asked to be returned home. Attempting to return Clara home, the Doctor ended up in Glasgow by mistake. However, Clara decided to go out for coffee with the new Doctor after the Eleventh Doctor called her and encouraged her to help the Doctor through his regeneration. (TV: Deep Breath)

Am I a good man?
Leaving Clara behind in Glasgow to get coffee, the Doctor shared an adventure with a mutant called 78351 during his quest for coffee. (PROSE: Lights Out)

Intending to return with the coffee, the Doctor saved a Combined Galactic Resistance fighter pilot named Journey Blue from a Dalek Saucer attack, though left her brother behind in the explosion. After prompting her into asking nicely, the Doctor returned Journery to her command ship, the Aristotle, where Colonel Morgan Blue introduced him to a Dalek that had developed a fault and turned good.

Returning for Clara, three weeks later from her perspective, the Doctor asked her if she thought he was a good man, a question that Clara found herself unable to answer, and returned to base to help the Dalek. Joined by Journey and two other soldiers named Gretchen Carlisle and Ross, the Doctor and Clara used a Molecular nanoscaler to miniaturise themselves and enter the Dalek — whom the Doctor nicknamed "Rusty". After losing Ross to the Dalek's antibodies, the Doctor discovered a radiation leak from within the Dalek and learned that Rusty had turned good after seeing a star being born. Following the radiation, the Doctor discovered damage to Rusty's power source was slowly killing him, and repaired the damage with his sonic screwdriver.

However, fixing Rusty's power core resulted in the malfunction that turned Rusty good to be reversed, with Rusty's destructive nature returning, and causing Rusty to go on a killing spree, as well as send a distress beacon to summon the Daleks to the rebels' base. After getting slapped and lectured by Clara for his apathy, the Doctor realised he could turn Rusty good again by reawakening his memory of the star being born.

Instructing Clara to find a way to restore Rusty's memories of the star, the Doctor made his way to the Kaled mutant within Rusty to mind linked with him, causing Rusty to see the Doctor's hatred of the Daleks and destroy the Daleks that had responded to his distress beacon. Leaving to continue his crusade against the Daleks, Rusty commented that Doctor would have made a good Dalek before both of them left. After declining Journey's request to travel with him and Clara, the Doctor returned Clara home, both still unsure if the Doctor was a good man, but with Clara convinced he was at least trying to be one. (TV: Into the Dalek)

New adventures with Clara
Spending some more time on his own, the Doctor became alerted to a creature that disguised itself as a motorway to consume planets into other dimensions. Summoning Clara to assist him, the Doctor was surprised when the creature disappeared, unaware that Clara had tricked the creature into consuming itself. (COMIC: Road Rage) He and Clara then assisted the Paternoster Gang in defeating the scheme of Orestes Milton to weaponise people. (PROSE: Silhouette)

Deciding to give Clara the choice of their next destination, the Doctor took her to Sherwood Forest to meet Robin Hood, though the Doctor was sceptical of Robin's actual existence. He was proven wrong immediately on arrival when Robin shot his TARDIS with an arrow; however, he remained determined to prove Robin Hood and his Merry Men were a fake.

After participating in an archery contest for a golden arrow, the Doctor, Clara and Robin were caught by the Sheriff of Nottingham, who had allied with alien robots disguised as his knights. Escaping, the Doctor found out that the robots were trying to reach the Promised Land, but lacked sufficient gold to repair their engine. Believing Robin was also a robot, the Doctor was captured by the Sheriff as Clara and Robin escaped through a window. Leading a revolution in the Sheriff's dungeon, the Doctor was informed by the Sheriff that Robin Hood was not a robot, just as Robin came to his rescue and defeated the Sheriff. Assisting Robin with Clara's help, the Doctor helped launch the golden arrow into the ship to allow it to escape velocity and explode harmlessly in space.

Robin, having learned about the Doctor's story from Clara, noted that the two of them were not so different from each other. Both of them were people born into status and privilege, giving up both to live the life of an adventurer in order to fight injustice. (TV: Robot of Sherwood)

The Doctor and Clara used a goo bomb to foil the Sibro's attempt to weaponise a Conlanian clock tower, (COMIC: Chime Time) orchestrated a ceasefire in a war between anthropomorphic cats and dogs by allying them against an army of alien fleas that planned to attack every planet in the universe, (COMIC: Once Bitten) and helped the World Brain find a new way of life after crash landing on its factory planet. (COMIC: Crash Landing)

While investigating corruption in a distant colony, the Doctor was briefly framed for various crimes and locked up in the colony's asteroid prison until he exposed its darkest security measure. (PROSE: The Blood Cell)

Visiting the planet Hoopoe, the Doctor acted as Clara's lawyer after she was arrested for walking on the ground by the Court of Birds. His attempt to convince them she and him weren't cats backfired when the owls accused them of being mice, but the Doctor had foreseen this and had recruited the native cats to attack the owls with makeshifts wings, but ensured that the wings were too difficult to use properly, rendering them useless in the cats' pursuit of the owls. As he left with Clara in the TARDIS, the Doctor rewarded the cats with a box of canned tuna. (COMIC: The Court of Birds)

During one of Clara's breaks from the TARDIS, the Doctor became obsessed with the idea that a creature designed to hide was following him around and that everyone was similarly being followed. Visiting Clara for help in finding the hiders, by using the TARDIS telepathic circuits to pilot into her past. However, Clara got distracted by a phone call from her date Danny Pink and piloted them into his past instead, back when Danny was called Rupert as a child. Finding a figure under Rupert's bed sheet, the Doctor had Clara and Rupert turn their backs to allow the being to walk out the room unobserved, leaving them unsure if it really was a creature or just another child playing a trick on Rupert.

Returning Clara to her date with the adult Danny Pink, the Doctor continued to follow his theory by trying to use a trace of Clara left in the telepathic circuits, ending up at the end of the universe where a time traveller named Colonel Orson Pink, Danny's descendant, had been trapped for six months. Intrigued by how following Clara's timeline led him to Orson, the Doctor returned for Clara and had them wait at the end of the universe for the night, believing it to be the perfect time to find out if the hiders were real. Finding a chance to confront the creature outside the ship, the Doctor sent Clara into the TARDIS and seemed to get a look at what he's been chasing before the atmospheric shell broke and Orson had to rescue him. As the Doctor was knocked out, and the TARDIS seemed to be under attack, Clara used the telepathic circuits to fly the TARDIS away.

Waking up to find Clara gone, the Doctor called out to her and inadvertently alerted his younger self to Clara's presence. Before he could investigate, Clara re-entered the TARDIS and made him promise to leave and not find out where they had landed. Afterwards, the Doctor returned Orson and Clara to their own times and, satisfied by what he had learned, underlined the word "Listen" that the creature had written on his chalkboard. (TV: Listen)

The Doctor planned to rendezvous with Clara at Coal Hill School, but instead arrived at a replica of the school on an unnamed planet, where Clara and Jeff Delobel, a French teacher, had been abducted by primitive aliens planning to infiltrate Earth via Coal Hill School. In order thwart the invasion, the Doctor told the aliens a tale of Earth's Guardian, informing them that he was the guardian, scaring the aliens off. (COMIC: The Monsters of Coal Hill School)

Resuming their travels, the Doctor and Clara helped stranded Seevith launch their ship, (COMIC: More Than Meets the Eye) and helped Professor Faster end the 17th century witch trials. (COMIC: Witch Work)

Returning to pick up Clara, and persuade her to away from a date with Danny Pink in favour of other travel destinations, the Doctor received a call from Madame Karabraxos, who requested he free the Teller and its mate from the Bank of Karabraxos, as he had done on the day she met him. Realising the ramifications of this request, the Doctor built up the identity of "the Architect", using this identity to stage a bank heist for him to commit, with the assistance of Clara, an augmented human named Psi, and a shape shifting mutant human named Saibra.

Using memory worms to erase the plan from their minds and prevent the Teller from alerting the young Karabraxos, the Doctor and Clara found themselves already in the Bank with their accomplices, their last memory being the TARDIS phone ringing.

Receiving instructions from the Architect on their location, objective, and the Bank's security system, the team infiltrated the Bank. Entering a safety deposit box, Team Not Dead - the Doctor's name for the assembled team - set of a dimensional shift bomb into a service corridor, where the team found a briefcase containing six teleporters disguised as atomic shredders.

Seemingly losing Saibra and Psi to the shredders when the Teller locked onto them, the Doctor figured out that time travel was involved with the heist plan when a perfectly-timed solar storm unlocked the Bank's vault. Retrieving what the Architect had promised Psi and Saibra as payment, the Doctor and Clara were caught by the Teller and delivered to the bank manager, Ms. Delphox. After Delphox left them to be executed, the Doctor and Clara were saved by Psi and Saibra, who revealed the true nature of the "shredders".

Venturing into the Bank's private vault to find his and Clara's reward, the Doctor instead found Director Karabraxos, and discovered that Delphox, as well as a majority of the bank's staff, was an exact clone of Karabraxos. Seeing Karabraxos' hatred of her own clones caused the Doctor to have an epiphany on the identity of the Architect, and he gave his phone number to Karabraxos as she fled from the solar storm about to hit the Bank. Subjecting himself to the Teller's powers, the Doctor regained his lost memories and realised the true objective of the bank heist. Freeing the Teller and its mate to a place to live in solitude, the Doctor then parted ways with Psi and Saibra, giving them their rewards, and returned Clara home for her date. (TV: Time Heist)

The Doctor and Clara were later pitted against the Wyrresters during their second attempt to invade Earth, with the Doctor also travelling back to ensure the failure of their first attempt and Clara briefly switching bodies with a Wyrrester before they were defeated. (PROSE: The Crawling Terror)

The Doctor and Clara were left to the mercy of sand piranhas while chained to posts on a Desert planet, rendezvoused with fish people, (TV: The Caretaker) were saved from an Aaraanandal slime beast by a survivor of the 22nd century Dalek invasion named Simon, (PROSE: When the Wolves Came) and outran soldiers to escape in the TARDIS. (TV: The Caretaker) During Christmas, the Doctor and Clara saved a small village from a Cephla. (COMIC: Gift Snatched!)

Planning to visit Eden 2, the Doctor was joined by a reluctant Clara, after she phoned him to drop her off at the school after she overslept. When the duo arrived, they found the under assimilation by the Vladlack, but it turned out that the planet was a trap, to lure in and arrest invaders of planets. Fearing that innocents could be inappropriately punished, the Doctor set up a warning beacon around the planet, then dropped Clara off at Coal Hill School. (COMIC: Freeze)

Meeting Danny and Courtney
Discovering a Skovox Blitzer near Coal Hill School, the Doctor went in "deep cover" as the school's temporary caretaker to dispatch of the killer robot, much to Clara's dismay.

Initially planning on using chronodyne generators to send the Blitzer into the future, the Doctor's plan was accidentally foiled by Danny Pink; Danny had seen the Doctor act suspicuously and believed the devices were of malicious intent, deactivating some. As a result the Blitzer was sent a short time into the future, rather than centuries. After Clara introduced him as her boyfriend, the Doctor took a dislike to Danny as he was a former soldier and feared he wasn't good enough for Clara. He changed his plan to using a communication device to make the Blitzer think the Doctor was its superior.

Rather a few days, the Blitzer returned during the next evening; to the Doctor's surprise, Danny used his military training to help keep the Blitzer occupied, allowing him to repair the malfunctioning device. After successfully commanding the Blitzer to deactivate with Danny's help, the Doctor took into space and ejected it from the TARDIS, taking Clara's troublesome pupil Courtney Woods with him after she discovered his identity, deciding that there was no harm in having Courtney tag along as a travelling companion, (TV: The Caretaker) but didn't see anything special in her. (TV: Kill the Moon)

Further adventures with Clara
The Doctor and Clara travelled to the planet Isen VI, so that Clara could practice skiing for a school trip. Although the Doctor remembered it as a very cold and snowy planet, it had been converted to a warm and tropical paradise. After rescuing Clara from monkey-like creatures, the Doctor found an artificial leaf, which led to him and Clara being accused of trespassing by the planet's owner, Kano Dollar. The Doctor found that as a result of the planet's manipulation a global cataclysm was imminent, but Dollar wouldn't listen. The Doctor and Clara rescued two workers from an underground earthquake with the TARDIS and moved to a cavern beneath the tower. The Doctor had discovered a Gallifreyan signal and wanted to investigate. They found a giant terraformer, which had fused with a ship underground. From the ship came a Hyperion called Rann-Korr, who announced the universe would fall.

The Doctor released the ship's coolant gases, allowing him and the others to escape to the TARDIS. He explained that Rann-Korr's reanimation was a result of the terrorformer's work, and conceded he had no plan to defeat him. They returned to the surface and made plans with the workers. The Doctor returned to confront Rann-Korr in a last stand. As Rann-Korr prepared to kill the Doctor, the terrorformation was reverse-engineered, returning the area of Isen VI around him to its original icy state. The Doctor escaped in the TARDIS, and Rann-Korr was extinguished in the cold. He and Clara bid farewell to the workers and left. (COMIC: Terrorformer)

While Clara was having her portrait painted by Leonardo da Vinci in 1505, the Doctor received a summon to 2315 India from an old acquaintance of his, Tiger Maratha, who foresaw a timeless evil. The Doctor and Clara arrived in 2315 to find he had been killed and drained of life, and along with Tiger's daughter Priyanka were confronted by police who attempted to arrest the Doctor. Escaping capture, Priyanka told the Doctor and Clara that Tiger had worked for a group known as the Family Scindas. The Doctor, Clara and Priyanka traveled to the Scindas' ancestral home to find information, however the Doctor stumbled through a dimensional door into 1825 India, where he was attacked by a demon but rescued by renegade amazon Rani Jhulka. The Doctor and Rani found a necro-cloud harvesting the spirits of the dead, and then attacked by more of the demons. Before they could be overpowered by the demons, the TARDIS arrived, Priyanka having unintentionally activated the telepathic circuits. She told the Doctor Clara had been taken by the demons.

Back in 2315, the Doctor, Priyanka and Rani found a final recorded message from Tiger made before his death, in which he explained he had collected three of the four mythic swords of the goddess Kali for the Family Scindas and had a premonition of evil over the swords. The Doctor was then summoned to see Chandra Scindas, the patriarch of the Scindas family. The Doctor deduced that they were beings known as the Kaliratha, putting themselves throughout time and space and Hindu mythology. Chandra revealed he had Clara hostage, ready to be burned by the Exodus rocket, forcing the Doctor to agree to find the fourth sword of Kali for them. The Doctor, Priyanka and Rani collected the fourth sword and returned to Chandra, who revealed he had used Clara as a host for the resurrection of Kali. Priyanka took control of the rocket while the Doctor battled with Kali. The Doctor revealed he hid his sonic screwdriver in the fourth sword, so that Kali unwittingly freed the evil spirits from her and released Clara's body, while Rani killed Chandra. The Doctor, Clara, Rani and Priyanka then attended a festival in Mumbai. (COMIC: The Swords of Kali)

While attempting to hang flowers on the exterior of the TARDIS, the Doctor was spooked by a future Clara and fell out of the TARDIS into the orbit of an asteroid. When Clara's attempt to avert the crisis ended up causing it, the TARDIS was able to save the Doctor by creating a time field around him. (PROSE: A Long Way Down)

Picking up a signal, the TARDIS arrived on the Quartz Wastes of Asmoray. Although the Doctor believed it was an uninhabited wasteland, Clara pointed out there was a harvester nearby extracting electricity from the quartz. The Doctor and Clara were brought aboard the harvester by two workers, where beings within the electricity had broken through and killed four workers. Their leader, Luther, was insistent on continuing their work regardless. Investigating, the Doctor and Clara found the creatures were only attacking because they were being attacked - sucked into the harvester's storage batteries. With Clara's help, the Doctor was able to free the electricity beings back into the quartz. (COMIC: The Body Electric)

After stopping a hostile invasion in the future, the Doctor traveled to UNIT HQ, where he had just been in time to shut down a Void portal. The Doctor came into conflict with the Fractures, natives of the Void that possessed humans, who believed they had to drag anyone mark with Void stuff into the Void to protect reality from unraveling. The chaos was started by a UNIT scientist from an alternate Earth, Paul Foster, who wished to be with a version of his family. Recruiting UNIT, Kate Stewart and the Fosters' help, the Doctor and Clara opened the Void, drawing the Fractures back inside and freeing their victims. At Clara's insistence, the Doctor allowed the alternate Paul to join his family in their universe, knowing the Fractures were entirely out for him now. (COMIC: The Fractures)

Fallout with Clara
At Clara's urging, the Doctor took her and Courtney to the Moon in 2049, so that Courtney could be the first girl on the Moon to bolster her confidence. Landing instead in a recycled space shuttle heading for the moon, the Doctor was informed by Captain Lundvik that the moon had inexplicably gained mass, and that she and her crew were going to use nuclear bombs to dispose of the additional mass.

Investigating a disused mining base from a previous mission, the Doctor, his companions and the astronauts found corpses preserved in webs and research that suggested that the moon was disintegrating. Soon after, the group was attacked by a spider creature, which Courtney killed with washing up equipment, but not before Lundvik's crew were killed.

Taking a scared Courtney back to the TARDIS, the Doctor voiced his uncertainty of the Moon's fate to Clara, calling it a "gray area" in time. Exploring the moon's surface for the reason behind the deterioration, the Doctor, Clara and Lundvik discovered a horde of spider germs beneath the Moon's surface, as well as amniotic fluid, prompting the Doctor to investigate beneath the Moon for answers.

Scanning the Moon's core, the Doctor discovered that the Moon was, in fact, an egg for an ancient creature that was hatching. Reuniting with Clara and Lundvik after the shuttle and the TARDIS fell into a canyon, the Doctor informed them of his discovery after establishing contact with Courtney's phone. While Clara and Lundvik argued about killing the creature for the sake of the Earth, the Doctor had Courtney bring the TARDIS to him via DVD, deciding that it was not his place to decide the Moon's future, and left in his TARDIS for Clara, Lundvik and Courtney to decide on behalf of humankind.

After Clara chose to spare the creature, despite humanity voting for its death, the Doctor returned for the three women, taking them to a beach on Earth to see the creature hatch and the Moon harmlessly disintegrate in Earth's atmosphere. Confirming that the sight of the moon hatching kick started the humans pioneering into space, and seeing the creature hatch a new egg with same mass as the old Moon, the Doctor returned Courtney and Clara to Coal Hill School.

However, Clara, angered by the position the Doctor had put her in, asked the Doctor if he had known the egg was harmless, which the Doctor confirmed as true. Tired of the Doctor's apathy, Clara argued with the Doctor about how he had almost caused her to kill an unborn creature. He defended that he was helping the human race by not playing a part in this choice. However, Clara had been deeply hurt by the Doctor's constantly patronising attitude toward humanity, and now that he had demonstrated it with her, Clara felt reduced to the likes of an idiot in the Doctor's eyes. With tears rolling down her face, she told him to leave and not return for her. The Doctor was left stunned by her reaction and immediately took off. (TV: Kill the Moon)

Time alone
Responding to a distress call from Dalek prisoner aboard a Cyber Ship, the Doctor discovered that the Daleks, Cybermen and Sontarans were searching for the Orb of Fates to gain control of a powerful Time Lord weapon called the Starbane. The Doctor joined forces with the Dalek prisoner, who had been altered by the Cybermen and "seen the light" and nicknamed it "Lumpy". Following the Orbs' Artron energy to the Cyber-tombs of Telos, the Doctor restored a minimum of Lumpy's power, not trusting the Dalek to allow full use of its power, and sent him to retrieve the second Orb while he studied the first in the TARDIS.

As Lumpy descended into the depths of Telos, the Doctor discovered that the Orbs were powered by temporal energy; The only way to destroy them was to create a temporal implosion. Leaving Telos for Sontar, the Doctor and Lumpy were trapped in a stasis field by Major Skar, but the Doctor was able to open the field and allow Lumpy to escape undetected while he stayed behind as a diversion. After Lumpy acquired the last Orb and deactivated the stasis field, the Doctor escaped with Lumpy, deciding it best to stay clear of Sontar for a while. They next travelled to the Starbane. However, Lumpy pointed out that it was already occupied by Daleks. When learning Lumpy was not turned to good, Doctor had found a way to access Lumpy's controls remotely and used this ability to destroy the Starbane. (GAME: The Doctor and the Dalek)

On Christmas Eve 2014, the Doctor teamed up with Ceri, an understudy, to fraught an Addos attempt to recreate a Mummers play by genetically altering actors from the Palace Theatre. (PROSE: Behind You)

Clara rejoins
Reuniting with Clara for a farewell trip, the Doctor took her to a space-bound Orient Express. He later confessed to her that he had chosen the destination with an inkling that something exciting would happen after having been lured with phone calls, mysterious summons and free train tickets.

After discovering the death of an elderly passenger, and urging himself to investigate, the Doctor went to the engine room to examine the dead passenger's Excelsior Life Extender, meeting Chief Engineer Perkins in the process, and learned the rumor of the Foretold. Seeking advice from Emile Moorhouse, a fellow passenger who was a Professor of Alien Mythology, the Doctor soon discovered a second death had occurred in the kitchen.

Confronting Captain Quell with his theory, but getting ignored, the Doctor joined Perkins and Moorhouse in the engine room to research the deaths. Calling Clara to update her, the Doctor discovered that she and Maisie Pitt were trapped in a storage cart with a sarcophagus. Fearing that Clara was trapped with the Foretold, the Doctor tried to rewire the door open, only to find the sarcophagus empty, and himself under arrest by the Captain for being a stowaway.

However, after witnessing a third death firsthand, Quell realised that the Doctor was right and allied with him, just as the Doctor deduced the true nature of the Orient Express; the passengers were all experts and scientists in specific fields of study, gathered there to study the Foretold. With a lab revealed and the hologram passengers disappearing, the train's computer, Gus, gave the scientists the necessary instructions and equipment. Losing Moorhouse to the Foretold, the Doctor and Perkins figured out that the Foretold was targeting the weaker passengers after looking at the medical history of the previous victims, just as Quell was killed by the creature, as he had post-traumatic stress, but not before he gave the Doctor the necessary description to defeat the Foretold.

Realising that Maisie was next due to her breakdowns, the Doctor told a reluctant Clara to bring Maisie to the lab. Arriving there, the Foretold appeared to Maisie, but the Doctor saved her by implanted a replica of her grief into his head, confusing the Foretold into thinking the Doctor was Maisie. Deducing that the Foretold was an ancient soldier augmented with technology, the Doctor surrendered, and, after a final salute, the ancient soldier crumpled to dust, with only the technology that kept him alive remaining.

With the objective completed, Gus released the air out of the cabin, but the Doctor beamed all the dying passengers into the TARDIS, and tired to hack Gus to find out who had created him, but this trigged a security measure, causing the train to self-destruct. Dropping everyone but Clara and Perkins off at the nearest civilised planet, the Doctor waited for Clara to awaken on a beach before explaining everything.

Back in the TARDIS, the Doctor invited Perkins to travel with him, but Perkins politely declined and he and the Doctor bade each other goodbye. Reflecting on a conversation she had with Maisie, Clara, having forgiven the Doctor, decided to continue travelling with him, telling the Doctor that her leaving was all Danny's idea. (TV: Mummy on the Orient Express) The Doctor landed on the Pollyanna, the first of the Ninth Era sunships, which had been on an expedition to circumnavigate the Sun. Seeing one of the Umbra come out of the Sun and enter a plasma intake, the Doctor rushed to the plasma lab and carried the injured Professor Alice Dubrovnik to safety. The Umbra, who had been trapped in the chromosphere for millions of years, began swarming the Pollyanna, anchoring the ship to the Sun to try and hijack it and use it as a way of reaching Earth. As the Umbra on board took on more humans as vehicles, the Doctor was ejected out of a plasma intake to attract the Umbra to his regret. He set up the final link to Alice's graviton inverter on the hull of the ship, allowing Alice to briefly boost the inverter and create a secondary gravity envelope, which inverted the gravity and the heat, freezing the Umbra on the ship to death. (COMIC: The Eye of Torment)

Trying to return Clara home, the Doctor instead landed in Bristol when the Boneless began draining power from the TARDIS, drawing it off course and causing the exterior to shrink. Sending Clara to find the cause, the Doctor re-entered the TARDIS to study the shrinking effect, only for the TARDIS to shrink further, trapping him inside. Equipping Clara with his psychic paper and sonic screwdriver, the Doctor used nanotechnology to hack into Clara's optic nerve and establish a visual contact with the outer world. After Clara recruited the aid of a local named Rigsy, pretending to be the Doctor while doing so, the duo discovered that creatures from a two-dimensional universe were killing and dissecting missing locals to understand their three-dimensional bodies.

After discovering that Clara had lied to him about Danny's approval, the Doctor realised that a mural dedicated to local missing people was in fact the missing people, killed and worn by the creatures as camouflage. With Clara leading a gang of surviving community servers, the Doctor theorised that the creatures were trying to communicate, and that the deaths were but a mere misunderstanding. When the theory was proved wrong, the Doctor invented a 2Dis — a device that could reverse the creatures' flattening abilities — as Clara and her gang retreated to an underground tunnel.

After Clara accidentally dropped the TARDIS onto a train line, the Doctor activated the TARDIS' siege mode to protect it from an oncoming train. Now unable to even open the doors, which had been removed by the activation of siege mode, and with the life support systems failing as the power drain continued, the Doctor congratulated Clara for being worthy of the title Doctor, unsure if she could hear him or even if she was still alive. Clara and Rigsy were able to trick the creatures into supplying the TARDIS with the necessary power to restore it to full working conditions. Naming his adversaries the Boneless, and declaring himself as "The man that stops the monsters." the Doctor banished them back to their home universe. The Doctor then took the survivors to the surface. (TV: Flatline)

The Doctor tried taking Clara to the frost fair in 1641, but instead, was drawn off course and landed in the Sahara Desert in 1941, where they were captured by Nazis. While requesting business with Field Marshall Rommel, the Doctor learnt from Rommel that Germany's allies, the Tuareg tribesmen, had made new extraterrestrial allies. The Doctor believed it was urgent to see the Tuareg and went with Rommel to meet them. After being taken to the tribe's chieftain, Bhaki, to see these "men from the stars" Bhaki introduced the Doctor and Rommel to the Tuareg's new allies, the Sontarans. The Sontaran commander Kygon Brox, believing the Doctor was looking for the Sontaran world engine weapon, the Warsong, tried interrogating the Doctor with a mind scythe. The Doctor made the link go the other way, and Kygon explained the history of the weapon to the Doctor. He told the Doctor that the Warsong was taken to Earth, and that there was someone seeking the weapon after signals from it began increasing exponentially. The Doctor realised that the "highly decorated" Nazi officer Heinz Bruckner wasn't who he claimed he was, but a Rutan spy and watched from a distance as the Warsong was triggered.

Realising that Bruckner took Clara with him to the Warsong's activation, the Doctor came up with a plan to converge the Allied, Axis and Sontaran forces towards the still-forming Warsong to distract Bruckner while he and Rommel snuck into the Warsong and broke through its defences. The Doctor stopped Bruckner from conducting the milennia-old preset programming of the Warsong by using a Sontaran osmic projector to send Bruckner's trigger mechanism through time. Rommel threw Bruckner into the Warsong, killing him, while the Doctor destroyed the "orchestra" of the Warsong by using his sonic screwdriver to blow it up. Afterwards, he brought Clara to the frost fair. (COMIC: The Instruments of War)

After spending some time on his own, the Doctor landed in London, only to find it and the rest of the world overrun by trees after Maebh Arden, a student of Coal Hill Year 8 Gifted and Talented Group under Clara and Danny's care, looked for the Doctor after hearing about him in what Maebh believed was a thought that came from Clara. With his theories constantly being proven wrong, the Doctor came to the conclusion that the trees' sudden overgrowth was an act of aggression, while also dealing with Clara's students in his TARDIS after Clara and Danny arrived to collect Maebh, only for Maebh to slip away in the commotion, just as the Doctor noticed her homework had predicted the events of that day.

Following Maebh deeper into the forest, the Doctor discovered that a sentience identifying itself as "the life that prevail[ed]" had caused the overgrowth, in preparation for a devastating solar flare about to hit the Earth. Believing Earth doomed, Clara inquired him to use the TARDIS as a lifeboat, only to inform him that she had said that to get him back to his TARDIS so he could survive the catastrophe alone. Despite some reluctance, Clara eventually convinced him to leave. Immediately afterwards, having discovered upon further reflection that the trees were going to absorb the harmful solar flares by pumping the atmosphere with excess oxygen, "like a massive, highly inflammable airbag", the Doctor returned to Clara and explained his discovery to the Gifted and Talented Group.

When he was informed of a government operation aiming to destroy the trees, the Doctor opened every mobile network on the planet to allow Maebh the opportunity to deliver a speech written by the Gifted and Talented Group to leave the trees alone. With Danny taking the children to their homes, the Doctor and Clara watched the trees that grown around the world harvesting and extinguishing the solar fire in the TARDIS, and then returned to watch the trees disappear on Clara's balcony. (TV: In the Forest of the Night)

The darkest hour
The Doctor rejoined Clara for a trip, where she suggested they go see a volcano. As the Doctor set the TARDIS to go, Clara attempted to put a mood patch on his neck, but the Doctor realised what she was doing and turned it on her. Not realizing she was drugged, Clara imagined being at the volcano and throwing all the Doctor's TARDIS keys into lava, to blackmail him to save Danny, who had been killed in a road accident. The Doctor refused, and Clara came out of her dream state after destroying all the TARDIS keys. Despite her betrayal, the Doctor agreed to search for an afterlife to find Danny.

The Doctor and Clara arrived at 3W, which held dead bodies in water tanks. They were greeted by, who identified herself as a greeting droid and kissed the Doctor as part of her greeting routine. They met Dr. Chang, who showed them the use of dark water in the mausoleum. Clara received a call from Danny, who was in the Nethersphere, and the Doctor and Chang left her to take it.

The Doctor and Chang discovered that the water tanks that held the bodies were being drained by Missy, who killed Chang and revealed that all the tanks held Cybermen, who were preparing to invade Earth. Escaping the building, which he discovered St Paul's Cathedral, the Doctor tried to warn away nearby people, but Missy called out his warnings as insanity, and told him it was too late. The Doctor asked for her identity, and, to his shock, Missy revealed she was, (TV: Dark Water) before she and the Doctor were apprehended by UNIT and brought aboard the plane Boat One, where the Doctor was made President of Earth to battle the Cybermen. Missy overpowered UNIT, killed Osgood, and attempted to kill the Doctor by blowing up the plane, but the Doctor survived his fall to Earth by skydiving into the TARDIS. He travelled to a cemetery and reunited with Clara, who was comforting a converted Danny. Missy arrived and, as a "birthday present", gave the Doctor control of all the Cybermen.

Missy planned to turn the Doctor into the leader of the new army, intending to prove that the two of them were not that different after all, believing that she had put him in the impossible position of either accepting control of the army and using it to 'save' the universe or letting humanity die and conquer the universe as the Cybermen. However, reflecting on his past, the Doctor realised that he was just a man in a box who travelled around to help where he could, proclaiming that he was not a good man, a bad man, the leader of an army or a President. He then turned command of the army over to Danny, realizing that the teacher had held on to his love for Clara even with his emotions deactivated, who led the Cybermen into the clouds where they self-destructed and stopped the rainfall from converting the living. A devastated Missy told the Doctor he could find Gallifrey in its original location with coordinates she provided, but Clara threatened to kill Missy for what she had done, until the Doctor prepared to do it himself. However, a rogue Cyberman disintegrated Missy instead. The Doctor realised it was his old friend the Brigadier — resurrected as a Cyberman — helping him again. The Doctor saluted the Brigadier, fulfilling a life-long wish of his old friend, noting that the Brigadier would never be anywhere else but by his side when Earth and the Doctor faced their darkest hour.

The Doctor entered the coordinates Missy gave him into the TARDIS and looked at his location, expecting to find Gallifrey. However, it turned out the coordinates were false and led to nowhere. With his only way to find Gallifrey gone, the Doctor attacked the TARDIS console in a furious rage, before breaking down emotionally. Meeting up with Clara in a café, and believing that she was back with Danny, the Doctor lied to her that he had found Gallifrey so as to allow her to continue with her life. Upon hearing this, Clara told him that she was happy and ready to settle down with, and they both bid farewell and parted ways. (TV: Death in Heaven)

Dreaming of Santa
Some time later, the Doctor was attacked by a dream crab, which put him into a scenario where he was brooding alone in his drifting TARDIS, (TV: Last Christmas) and was snapped out of his funk as when he heard Santa Claus knocking on the TARDIS door, asking the Doctor what he wanted for Christmas. (TV: Death in Heaven)

The Doctor travelled to Clara's home and collected her from her rooftop, where she had also encountered Santa. Urging her to believe in him, they arrived at a North Pole base, which they found was under attack from dream crabs. Santa arrived to help with the problem, but Clara was attacked by a crab and fell into a dream state. As no one could find a way to remove the crab from her face, the Doctor let himself be attacked by one to get her out of her dream before the crab could kill her.

Entering Clara's dream, the Doctor found she was dreaming of spending Christmas with Danny, and leant that Danny was dead. The Doctor urged her to break out of the dream, after Danny bid her farewell. Waking up in the base, the Doctor came to the realisation that everyone in the base was dreaming, having been attacked by crabs after they arrived. They woke up from the dream and the Doctor and Clara prepared to leave, but Clara reminded the Doctor of Santa having been on her roof, and he realised they were still dreaming from different places and times. The infected personnel in the base began to attack the survivors, however, everyone managed to escape by dreaming Santa was flying them home. The Doctor, Clara and the base scientists flew over London as they each woke up back in their own times.

Waking up where he had been, the Doctor travelled to Clara's home and removed the dream crab attached to her, only to find it had been sixty-two years since he left her and she was now an old woman. Clara filled her in on the years, but the Doctor felt remorseful of leaving her when he did. Santa suddenly appeared and asked the Doctor what he'd do if he had another chance, and the Doctor woke up from his dream, this time for real. He saved the younger Clara from the crab. Spurred on by what could have happened to her, the Doctor invited her to resume her travels with him, and she accepted. They set off together in the TARDIS, the Doctor remarking that he rarely got second chances with his companions, and commenting that he didn't know who to thank for this one. (TV: Last Christmas)

Second chance with Clara
Discovering that a group of aliens were going to turn a planet of anthropomorphic pink hippopotami into stone, the Doctor intercepted the aliens at the early stages of their invasion and led them to ancient Egypt, where they petrified a large cat-like alien, creating the Sphinx and getting crushed in the process. He and Clara then returned to the planet of the anthropomorphic pink hippopotamuses to reverse the petrified effect. (COMIC: Petrified)

The Doctor and Clara turned Captain Ratlett's crew against him and showed them a better life, (COMIC: The Wheelers) were almost consumed by robotic bananas for stealing food from the moon Luna Schlosser, (COMIC: Five a Day) and saved the Cloud City of Mirmi 24 from being eaten by an alien snake. (COMIC: The Very Hungry Snake)

The Doctor and Clara travelled to a galactic auction in Earth's orbit where unclaimed storage was being bidded on, with the storage pod belonging to Hyphen T Hyphen, a reclusive collector, containing a mother Rigellan Hyper-Kraken, which began killing everyone when the pod was opened. Before the mother Hyper-Kraken's eggs could hatch, the Doctor widened the dimensional shunt's focus on the Hyper-Kraken, her eggs and the storage pods and safely transported them elsewhere. (COMIC: Space Invaders!)

Taking Clara to the Taj Mahal in India for a holiday, the Doctor was chosen to act as a hostage by Stellar Nexus while Nexus tried to get payment for Earth's supposed tax bills. When the Doctor challenged Nexus's claim by pointing out the illogic in his statement, and then insulted him by asking why he had never heard of Nexus's Empire, the Doctor was locked in a cell while an illusion of him was set against a dragon in a gladiator battle. When Clara managed to pilot the TARDIS into the Doctor's cell, the Doctor used his sonic screwdriver to deactivate Nexus's illusions, exposing that Stellar Nexus was a child-sized con artist whose entire Empire was an illusion. Sending the defeated Nexus away, the Doctor decided to treat Clara to a curry. (COMIC: Empire's Fall)

The Doctor took Clara to see the Lights of Tanzarr, but instead found that the Nameless Mist had entered his dimension and was threatening to devour the cosmos. Originally wanting to flee, the Doctor was convinced by Clara to save the inhabitants of Ferrous-Ferra, and was inspired to recruit Cold Steel to headline the "loudest rock show in history of sound". While Clara triangulated the transmissions to cover the local galaxy, the Doctor used the loud music to thwart off the Nameless Mist. With the day saved, the Doctor returned to the concert to celebrate with crowd surfing. (COMIC: The Big Hush)

The Doctor and Clara went on a tour of Snowcap University in Antarctica in 2048. While taking a helicopter ride, they learnt that one of the students, Polly Evans, had stayed behind at the end of term to join the classified Project Sub-Zero. When another student, Quinn Norton, who also a part of Project Sub-Zero, was killed in a helicopter crash the Doctor and Clara narrowly avoided being on along with Polly's father George, they returned to Snowcap U to investigate. With the help of the spy Paul South the Doctor found an ice cavern where the missing students had been experimented on, engineered by Dr Patricia Audley to survive in extreme cold. Paul, along with an echo of Clara's, Winnie Clarence, released most of the imprisoned humans from captivity. However, Winnie revealed that she decided to side with Dr Audley to alter her own body, to avoid dying to save the Doctor. (COMIC: Blood and Ice)

Personality
A cynical man armed with a dry, acerbic wit, a brutal honesty and a lot of internalised anger, the Twelfth Doctor was a radical change from his predecessor, adopting a less caring and more hostile nature. (TV: Into the Dalek, Robot of Sherwood, The Caretaker, Kill the Moon, Flatline, Dark Water; COMIC: The Swords of Kali) He was perfectly comfortable with placing his companions in danger if it meant appeasing his curiosity, often leaving them out of the details in his plans, or using them to distract attention away from himself. (TV: Deep Breath, The Caretaker, Kill the Moon, Mummy on the Orient Express) However, if he believed the situation was too dangerous for them, the Doctor would send his companions to the safety of the TARDIS while staring down the threat alone. (TV: Listen)

Despite coming across as uncaring, with a complete disregard for social niceties, he would fight to protect those in his care, and he would react with devastation if harm befell them. Such was his reaction to the death of a female Tyrannosaurus rex that had been inadvertently dragged through time by the TARDIS. (TV: Deep Breath) However, for the most part, the Twelfth Doctor was far more detached than his predecessors and was occasionally callous, reacting with indifference during his first encounter with Journey Blue, who had just lost her brother, (TV: Into the Dalek) and laughed at Orson Pink's name, though he apologised for the latter. (TV: Listen)

The Doctor also showed a strong compassionate streak, putting himself in harm's way to save Maisie Pitt from the Foretold, (TV: Mummy on the Orient Express) and assisting Clara in finding Danny in the afterlife, even after she had attempted to blackmail him. (TV: Dark Water)

While he described himself as having had "sophistication and timeless sartorial elegance" restored, (COMIC: Terrorformer) the Twelfth Doctor was not above acting childish; requesting a children's menu at Mancini's Family Restaurant, (TV: Deep Breath) sliding down stairs and ladders, (COMIC: The Monsters of Coal Hill School; TV: Death in Heaven) whistling "Another Brick in the Wall" to annoy Clara, (TV: The Caretaker) ecstatically steering Santa Claus's sleigh, (TV: Last Christmas) and bickering with the likes of Robin Hood and Father Christmas. (TV: Robot of Sherwood, Last Christmas)

The Twelfth Doctor showed even less restraint than his predecessor, and would get frank and physical with his enemies. (TV: Deep Breath) However, he had a conflicted sense of morality and struggled with his inner darkness. While he sometimes voiced preconceptions about the Daleks or human nature, he often questioned his own judgement afterwards. Indeed, behind his cold exterior was a man who was extremely self-reflective, to the point where he questioned whether he was still a good man. (TV: Deep Breath, Into the Dalek) The Doctor was well aware of the fact that he often found himself in situations that forced him to make terrible decisions, (TV: Mummy on the Orient Express) and believed he was overbearing, manipulative and consciously aware of his own intelligence. (TV: Time Heist) Eventually, he came to the conclusion that he was neither a good nor bad man, but rather just "an idiot, with a box and a screwdriver. Just passing through, helping out, learning." (TV: Death in Heaven)

Though he retained a respect for humanity, the Doctor would insult humans for being slow minded and violent, dubbing Earth the "planet of the pudding-brains." (TV: Deep Breath) Nonetheless, he tolerated the company of those who could engage him intellectually, as with Perkins and Osgood, (TV: Mummy on the Orient Express, Death in Heaven) and claimed to respect humanity enough to allow it to determine its own future without any interference from him. (TV: Kill the Moon) As with his previous incarnation, the Twelfth Doctor also liked people who got straight to the point, and thought that anyone who wasn't scared in life-threatening situations was an idiot. (TV: Last Christmas)

Though he did not know the reason, (PROSE: The Blood Cell) the Doctor expressed a strong dislike for soldiers, (TV: Into the Dalek, The Caretaker) though retained a respect for the Brigadier. (TV: Death in Heaven) He was also easily annoyed by swashbucklers who did not take things seriously. (TV: Robot of Sherwood) He also claimed to dislike liver, karaoke, mime, babysitters, bantering, salutes, (TV: Deep Breath, Into the Dalek, Robot of Sherwood, Death in Heaven) being taken prisoner, (COMIC: Terrorformer) and pantomime. (PROSE: Behind You) He did, however, like "show-stopping [entrances]". (COMIC: Terrorformer)

Unlike his immediate predecessor, the twelfth incarnation was not an affectionate individual, failing to return Clara's hugs, or protesting against them, believing they were just another way to hide one's face, (TV: Deep Breath, Listen, Death in Heaven) and also disliked holding hands with others. (TV: Last Christmas) He was momentarily dumbfounded when Maid Marian pecked him on the cheek in gratitude for saving her, (TV: Robot of Sherwood) and reacted with horror when snogged by. (TV: Dark Water) In a moment of excitement, however, he kissed Clara's forehead while complimenting her brilliance. (COMIC: The Big Hush)

Though he initially stated that murder was against his moral code, the Doctor showed a willingness to kill the Half-Face Man if he had to, though with some reluctance, first offering him a drink of alcohol and trying to persuade the clockwork droid to self-destruct of his own free will before engaging in fisticuffs. (TV: Deep Breath) He also stated that, despite how much he hated him, he had no intention of killing the Architect, (TV: Time Heist) but was willing to kill to spare Clara from doing it. (TV: Death in Heaven)

Unlike his immediate predecessor, the Twelfth Doctor was unwilling to alter the Web of Time, believing it was okay to send people to their deaths if history recorded them as deceased, (PROSE: The Crawling Terror) and also refused Clara's request to save Danny Pink from being hit by a car due to it being a part of her timeline, and undoing it would cause a paradox. (TV: Dark Water)

Much like his seventh and war incarnations, the Twelfth Doctor was heavily inclined to err toward a greater good and was willing to allow a few inevitable deaths if it meant saving the majority. Through this attitude, he acted like a pragmatist that would not hesitate to abandon someone whose fate was already sealed, nor mourn for an ally until his objective had been reached. (TV: Into the Dalek, Time Heist, Mummy on the Orient Express) However, the Doctor was still willing to save people if their deaths were not an immediate inevitability, desperately yelling for people to flee from St. Paul's Cathedral when the Cybermen began their invasion, (TV: Dark Water) and attempting to save Albert Smithe from the Dream crabs. (TV: Last Christmas)

Also like his previous incarnations, he relied on his companions to keep him from succumbing to his darker nature, but, unlike his predecessors, the Twelfth Doctor actively praised them for it, even claiming that Clara Oswald needed a "raise" for dealing with him. (TV: Into the Dalek)

In stark contrast to his previous incarnations, the Twelfth Doctor was more willingly to leave a situation if he believed he had nothing to contribute; abandoning Jason Clearfield when he could not offer medical assistance, (PROSE: The Crawling Terror) leaving Clara, Courtney Woods and Captain Lundvik to decide the fate of the Moon when he felt it wasn't his place to decide for them, (TV: Kill the Moon) and leaving the North Pole base immediately after defeating the Dream crabs, despite Clara claiming the team was still in danger. (TV: Last Christmas) The Doctor justified his attitude by pointing out the dangers of everyday life, claiming that "everything['s] dangerous if you want it to be", and once pointing out to Clara that he was not humanity's mother. (TV: Kill the Moon, Last Christmas)

By his own testament, the Twelfth Doctor did not suffer fools gladly, (PROSE: The Blood Cell) nor did he tolerate poor manners, even when held at gunpoint, and he believed that one should make requests politely, as well as avoid bad language. (TV: Into the Dalek, Kill the Moon)

Despite his grumpy nature, the Doctor got along well with children, giving Rupert Pink an enthusiastic pep talk about fear being a super power, (TV: Listen) and comparing the TARDIS' dimensions to the sugar in a coke bottle for Maebh Arden. (TV: In the Forest of the Night) After realising he had insulted Courtney Woods, he allowed her to be the first girl on the Moon to help her feel special. (TV: Kill the Moon)

An absent minded incarnation, the Twelfth Doctor had trouble recognising people's age group, (TV: Into the Dalek, The Caretaker, Kill the Moon, Last Christmas) often neglected to ask for people's names because they "weren't his area", (TV: Deep Breath, In the Forest of the Night) believed that minor clothing changes hid his identity, (TV: The Caretaker) and failed to understand Dr. Chang's joke about the application of dark water in public swimming pools. (TV: Dark Water)

The Doctor's hatred toward the Dalek species was rigid, with Clara describing it as "prejudice". He seemed conditioned to believe Daleks could not change and was closed-minded as he dealt with their presence. After his act of fixing a malfunctioning "good" Dalek caused it to revert to "evil," the Doctor was almost pleased that his belief of there being "no such thing as a good Dalek" was vindicated. This horrified Clara, who became angered to the point of slapping him. (TV: Into the Dalek)

Additionally, the Twelfth Doctor was, at times, critical of his previous incarnations' clothing; thinking that his fourth incarnation's scarf "looked stupid", (TV: Deep Breath) and regarded his immediate predecessor's fondness for bow ties as "a bit embarrassing", (TV: Time Heist) but complimented Osgood's bow tie as "nice". (TV: Death in Heaven) According to Affinity, the Doctor kept his predecessors "lodged in his head", and held a low opinion of them and himself. (PROSE: Silhouette) However, upon seeing Adrian Davies, a teacher at Coal Hill School with a resemblance to his previous incarnation, the Doctor, mistaking Adrian as Clara's boyfriend, arrogantly assumed that Clara was dating Adrian because of his uncanny resemblance to "a certain dashing young time traveller", reflecting more favourably to his predecessor. (TV: The Caretaker)

Much as his tenth incarnation expressed, the Twelfth Doctor associated regeneration with death, recalling Snowcap as "the place where he died". He viewed the process as "huge, [and] terrible", with his self-preservation preventing his memories of the experience from consuming him. (COMIC: Blood and Ice) He also believed that regeneration was to be used only when completely necessary, and to use it to fix a broken toe was "a waste of a life". (PROSE: The Blood Cell)

Habits and quirks
Much like his seventh incarnation, the Twelfth Doctor spoke with a Scottish accent, which he took as an entitlement to complain about things, (TV: Deep Breath) and was often prone to making subtle or climatic boasts. (TV: Deep Breath, Into the Dalek, Robot of Sherwood, Mummy on the Orient Express, Flatline)

When proposing a theory, the Doctor would use words such as "question" or "proposition", and would begin his conclusion with "answer" or "conjecture". After working out the important questions in his head, he waited for others to come to the same conclusion, becoming increasingly annoyed with each wrong question or answer they proposed. (TV: Deep Breath, Listen, Time Heist) When in a moment of realisation or thinking intensely, the Doctor would often tell people to "shut up", regardless if anyone else was speaking. (TV: Deep Breath, Listen,  Time Heist)

Like the Ninth Doctor labelling humanity as "stupid apes", the Twelfth Doctor would call them "pudding brains" when he found them slow-minded or stupid. (TV: Deep Breath, Robot of Sherwood, Flatline)

The Doctor often made puns, (TV: Into the Dalek, Flatline) used clever word play, (COMIC: Terrorformer) or quoted classic fairytales. (COMIC: The Eye of Torment, The Swords of Kali)

Unlike his first and eleventh incarnation, the Twelfth Doctor had a tolerance for alcoholic beverages. (TV: Deep Breath, Time Heist, Mummy on the Orient Express) Much like his third and eighth incarnations, he took his tea with extra sugar. (TV: Death in Heaven)

Much like his predecessor, the Twelfth Doctor also used hand gestures to extenuate a point, but applied more dedication to his movements, standing firm, while speaking with conviction, though would become more spontaneous when thinking intensely. (TV: Deep Breath, Listen, Time Heist, The Caretaker)

The Doctor made a habit of assigning nicknames to others, giving them names based on their appearance, by an accessory they carried or by their profession, (TV: Deep Breath, Into the Dalek, The Caretaker) owing to the fact he often chose to forget people, (TV: Last Christmas) and would insist on addressing them as their nickname, calling Danny Pink "PE", despite Danny being a Maths teacher, due to seeing him as more a PE teacher than Maths. (TV: The Caretaker, Death in Heaven)

When not out adventuring, the Doctor could be found jotting down equations and theories on various chalkboards in the TARDIS console room, or on hard surfaces that could bear chalk markings. (TV: Deep Breath, Robot of Sherwood, Listen)

The Doctor would occasionally offer out jelly babies in a similar way to the Fourth Doctor, but, unlike his fourth incarnation, the Twelfth Doctor kept his jelly babies in a cigarette case. (TV: Mummy on the Orient Express; COMIC: The Swords of Kali)

Skills
Highly observant, the Doctor was able to point out the Half-Face Man as non-human from his lack of interest in a burnt dinosaur corpse, and later noticed that he and Clara were trapped in a room full of Clockwork Droids because they weren't breathing, (TV: Deep Breath) as well as detecting a light shield aura, (TV: The Caretaker) finding Maebh Arden's "breadcrumb" trail, (TV: In the Forest of the Night) and foiling Clara's attempt to drug him with a sleep patch. (TV: Dark Water) He was also able to make accurate deductions from observing his surroundings, identifying the Aristotle as a medical ship within seconds of being on board, (TV: Into the Dalek) correctly guessing Captain Quell's backstory, and solving the riddle of the Foretold within sixty-six seconds. (TV: Mummy on the Orient Express)

While recovering from his regeneration, the twelfth incarnation showed his predecessor's ability to converse with other species, such as dinosaurs. (TV: Deep Breath) Much like his tenth incarnation, the Doctor also had a good sense of smell, which he used to assess his surroundings to deduce the time period he was in. (COMIC: The Swords of Kali)

Strong and durable, the Doctor was able to support his own weight single-handedly, wrestle the Half-Face Man into a corner, fall out of a high tree branch and shake off the fall quickly, and dive off a bridge into the Thames to swim across the river without being hampered, though the latter two events can be linked to him still being within the early hours of his regeneration, when his physical skills tend to be somewhat exaggerated. (TV: Deep Breath) At a later date, he smashed up the TARDIS console with his bare hands in a grief-stricken rage after learning that Gallifrey was still lost. (TV: Death in Heaven)

Like several of his predecessors, the Twelfth Doctor was a highly proficient swordsman, able to best Robin Hood in a duel using a spoon. (TV: Robot of Sherwood) He was also skilled in Venusian aikido, using it to defend himself from Abesse and disarming a distracted Robin Hood. (TV: Robot of Sherwood; PROSE: The Blood Cell) Even without his Venusian aikido, the Doctor proved to be skilled in unarmed combat. (TV: Deep Breath; COMIC: The Swords of Kali)

Despite initially forgetting how to pilot his TARDIS due to post-regenerative trauma, (TV: The Time of the Doctor) the Doctor soon mastered his way around the TARDIS console, being able to save Journey Blue by piloting the TARDIS around her, one second before her ship exploded. (TV: Into the Dalek)

Like his previous incarnations, the Twelfth Doctor also displayed telepathic abilities, being able to link his mind with Rusty to try and show the Dalek the beauty of the universe, (TV: Into the Dalek) put Rupert Pink to sleep by placing his index finger on his forehead, editing his memories while he did so, (TV: Listen) putting Clara through a telepathic scenario with the aid of a sleep patch, (TV: Dark Water) and sending messages on blackboards to Clara while a Dream crab was sedating her. (TV: Last Christmas)

A credited escapologist, the Doctor boasted at teaching Harry Houdini "everything he [knew]". (COMIC: The Swords of Kali)

As cunning as his seventh incarnation, the Doctor was able to spin a fatal outcome into an advantage, such as using Ross's death to help him, Clara, Journey and Gretchen Carlisle escape Rusty's antibodies, (TV: Into the Dalek) or using the deaths of Emile Moorhouse and Captain Quell as an opportunity to figure out a way to defeat the Foretold. (TV: Mummy on the Orient Express) He was also able to organise a bank heist to save the the Teller and it's mate, even erasing his planning of the heist to guarantee success. (TV: Time Heist)

Appearance
While his predecessors began their lives looking young, (TV: The Parting of the Ways, The End of Time) the Twelfth Doctor started out appearing very much older. He had short grey hair, a hooked nose and sharp silvery blue eyes, with big ears. (TV: The Time of the Doctor) He was of a light build. (COMIC: Chime Time)

Most changed were his eyebrows, which went from "delicate" (TV: The Time of the Doctor) to extremely thick and furrowed. (TV: The Day of the Doctor) Startled by the change, the Doctor described them as "attack eyebrows", which could "take bottle tops off" and were "ready to set up their own independent state of eyebrows". (TV: Deep Breath) He later considered his intimidating eyebrows as both a major contributor to his gravitas, (TV: Time Heist) and the reason many viewed him as a hostile. (COMIC: The Swords of Kali)

Tall and gaunt, he was once described by Clara as looking like a "grey-haired stick insect", (TV: Listen) with Robin Hood describing him as "pale as milk". (TV: Robot of Sherwood) Shona McCullough described him as a "skeleton man". (TV: Last Christmas)

Physically, he resembled Lobus Caecilius, a man he had met in his tenth incarnation, (TV: The Fires of Pompeii) with the Doctor himself noting that he had "seen [his] face somewhere before". (TV: Deep Breath)

Clothing
Immediately following his regeneration, the Doctor initially wore his predecessor's attire, a Victorian nightshirt, and then a coat that he "bought" from a tramp, before stealing a Clockwork Droid's suit in order to masquerade as one.

After having a chance to return to the TARDIS, though, the Doctor chose a new outfit for himself. He donned a navy blue cardigan with a white collared shirt, matching blue trousers, and black brogue boots. Over the top, he sported a thigh-length, dark blue jacket with red lining, often wearing it with the top button done. On his left hand ring finger, he had a pair of gold rings, a normal gold band and a second ring with a greenish amber setting that rested atop the first band. (TV: Deep Breath) Later in his travels he replaced his cardigan with a black waistcoat, worn with his white shirt. (TV: Flatline, Dark Water, Death in Heaven) The Doctor picked his look with the intention of "aiming for minimalism", but instead felt that he "came out with magician" after solidifying his wardrobe. (TV: Time Heist, Last Christmas)

Though his Crombie coat remained a constant staple of his appearance, the Doctor would wear variations of his attire, switching from vested garments with a white collared shirt for simply a dress shirt on its own, such as purple, (TV: Robot of Sherwood) dark blue, (TV: Time Heist) or black with a white polka dot pattern. (TV: Kill the Moon) Other times, he would dispense with the shirt as well and don a black crew neck jumper with small holes on the front. (TV: Listen, The Caretaker, In the Forest of the Night) On at least one occasion, he also wore a black hooded top over this shirt. (TV: Last Christmas)

While aboard the spacecraft Orient Express, the Doctor wore a very formal attire consisting of a black double-breasted evening jacket, black trousers, grey waistcoat, his black brogue boots, a white dress shirt and a black cravat. (TV: Mummy on the Orient Express)

Behind the scenes

 * Like the War and Ninth Doctors, the Twelfth Doctor debuted on television before his regeneration from his predecessor was screened.
 * His first words — "Kidneys! I've got new kidneys!" — keep to the modern tradition of new Doctors commenting on their bodies. Previously, the Ninth Doctor commented on his ears, (TV: Rose) the Tenth Doctor commented on his "new teeth", (TV: The Parting of the Ways) and the Eleventh on his legs. (TV: The End of Time)
 * In DWM 477, showrunner Steven Moffat jokingly answered one fan's question on what colour the Doctor's kidneys now were (he had complained he hated their colour) as "Froon. This is an entirely new colour, which only the Doctor can see."
 * His costume was revealed in DWM 470 and online earlier than planned to preempt a tabloid scoop.
 * He starred in The Daft Dimension, a comic strip published in Doctor Who Magazine.
 * Peter Capaldi wanted to wear his wedding ring as part of his Doctor's attire, and requested a prop to disguise it. He was given an amber ring with a gemstone that fits over the top of his original band. The First Doctor also wore a gemstone ring, and as such the Twelfth Doctor is the first incarnation since then seen to sport one. He is also the first incarnation since the Third Doctor to wear an ordinary ring.
 * Promotional material for Doctor Who Experience mentions that the green amber stone on the Twelfth Doctor's ring was 'allegedly' collected on the planet Raxacoricofallapatorius. However, this has yet to be stated in the narrative.

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