The Doctor's time stream

The Doctor's time stream contained all the Doctor's lives, all their deeds and memories, (TV: The Name of the Doctor) even those long forgotten. (TV: Once, Upon Time) As they led a complicated life, and made many enemies, who sometimes sought to have them come undone, the Doctor's time stream was subject to much manipulation. (PROSE: Unnatural History, AUDIO: The Secret History, et al.)

Forces like Omega, (PROSE: The Infinity Doctors) the Great Intelligence, (TV: The Name of the Doctor) the enemy (PROSE: Unnatural History) and Faction Paradox (PROSE: Unnatural History, Interference - Book Two, The Shadows of Avalon) all played a part in rewriting the Doctor's biodata retroactively, making it so that even the Doctor's origins were contradictory and uncertain, with so many possibilities becoming true at once, in paradox. (PROSE: Unnatural History)

The Doctor visited their time stream on at least two occasions, once as the Eleventh Doctor on Trenzalore, to recover Clara Oswald after she entered to save the Doctor's past from the Great Intelligence, (TV: The Name of the Doctor) and a second time, in a bid to save Yasmin Khan and Inston-Vee Vinder from a time storm in the fallen Temple of Atropos, as the Thirteenth Doctor. (TV: Once, Upon Time)

On this occasion, she had the opportunity to relive a long lost memory of her time as the Fugitive Doctor, near the end of her service to the Division. The Thirteenth Doctor nearly ended her life to stay longer, and find out what happened, but the Mouri threw her out. (TV: Once, Upon Time) This was also the space in which the Eleventh Doctor recognised — but still rejected — the War Doctor, who had scorned the name of the Doctor by deciding to destroy Gallifrey at the end of the Time War, (TV: The Name of the Doctor) though a different chain of events would soon be revealed. (TV: The Day of the Doctor)

Impact
As the Great Intelligence noted, the Doctor's time stream was a place of power, where many of the villains they had stopped might be given a second chance. (TV: The Name of the Doctor) As such, modifying the Doctor's history could lead to great catastrophe, with disasters they had once averted rippling out to become tidal waves. (TV: Turn Left, The Name of the Doctor) According to Clara, the Doctor could not help but have this impact, and became, himself, a "tidal wave" on history. (TV: The Girl Who Died)

During the Last Great Time War, the Dalek Time Strategist studied the timelines and came to understand numerous that the Daleks' timeline was "impossibly entangled" with the Doctor's as result of their numerous confrontations, going beyond into the post-Time War universe. As a result, the Strategist found that the Doctor could not be easily eliminated without consequences for Dalek history, with the Eighth Doctor observing that the Dalek was hesitant to kill him lest it interfere with its plans to kill him. (AUDIO: Restoration of the Daleks)

In one case, the Doctor's time stream was "unravelled" without impacting the overall timeline of the universe, as the Eleventh Doctor found himself on the other side, in Big Bang Two. He began to re-experience moments in his life, moving backwards from the point of his sacrifice, and decided to end his journey where this incarnation began, on the day he met Amelia Pond. He would return, however, from Amy Pond's nascent memories. (TV: The Big Bang)

In another, one of the Doctor's companions, Donna Noble, was made to have never meet the Tenth Doctor. This created "great, big parallel universe" in which the Doctor died defeating the Racnoss on Earth. (TV: Turn Left) In the original timeline, Donna was there to "stop [him]" from taking his rage too far. (TV: The Runaway Bride, Partners in Crime) Instead, a series of events led to the deaths of many allies and eventually, to the stars going out, (TV: Turn Left) as the Doctor and Donna were needed to stop the Reality Bomb. (TV: Journey's End)

Echoes
At one point, when the Third Doctor was attempting to repair his TARDIS, he saw a brief appearance of other versions of himself, together with Jo Grant. When they disappeared, he told Jo they had gone "back into their own time stream". (TV: Day of the Daleks)

Gatherings
During the First Omega Crisis, Lord President Pandad IV, despite the objections of High Chancellor Socra, had the Second and First Doctors extracted from their respective sections of the Doctor's time stream to aid the Third Doctor against Omega. (TV: The Three Doctors)

Using a Time Scoop, Lord President Borusa later took the first four incarnations of the Doctor and several of their companions out of their respective time streams again, to bring them to the Death Zone on Gallifrey. Here, they would play the Game of Rassilon on his behalf. In the case of the Fourth Doctor and Romana II, the attempt to lift them from the time stream was unsuccessful. They became trapped in a time eddy until the crisis was resolved. (TV: The Five Doctors)

Alterations
Using a biodata virus, Faction Paradox created an aberrant rewrite of the Doctor's timeline, where the circumstances of the Third Doctor's death were very different. (PROSE: Interference) The Edifice, a twisted version of the Doctor's TARDIS, contained the damage by keeping the two versions of the Doctor's timeline in a state of superposition, until the Doctor was finally able to collapse it towards the original version of events, purging himself of the biodata virus in the process and preventing the infected timeline's ultimate result for himself, a future where a war-mad version of himself became the avatar of Grandfather Paradox. (PROSE: The Ancestor Cell)

Wrong Doctor
was responsible for pulling the Fifth Doctor along his time stream, where he took the First Doctor's place in an adventure with Ben Jackson and Polly Wright. The Doctor had no memory of the original events, and needed to act as his first incarnation would, to preserve the timelines. (AUDIO: The Secret History) The Seventh Doctor was also sent to the Third Doctor's exile on Earth, alongside Jo Grant, where UNIT was taken over, (AUDIO: The Defectors) and the Sixth Doctor battled the Cybermen, replacing the Second Doctor, alongside Jamie McCrimmon and Zoe Heriot. (AUDIO: Last of the Cybermen)

Unravelling the Doctor's timeline would have been the Monk's revenge for the Eighth Doctor's supposed involvement in the loss of Tamsin Drew, but he failed, as each Doctor managed to preserve the original sequence of events. The Monk had wished to take the Doctor's place in history after erasing him from time. (AUDIO: The Secret History)

Wrong companions
Later, the Fifth Doctor jumped forward on his temporal vector, being pulled forward along his time stream to a later point in the same incarnation. From his point-of-view, he had just been with Adric, Nyssa and a younger Tegan Jovanka, and now found himself with an older Nyssa, from later in their travels, and a Tegan who'd only just returned to the TARDIS. Thinking it would be unwise to give away anything about the future, Nyssa decided to keep Adric's death from him, though she let slip that he'd taught her temporal telemetry. (AUDIO: Secrets of Telos) Meanwhile, the later Doctor had jumped backwards, getting an opportunity to speak with Adric again during an encounter with the Ice Warriors in 9th century Iceland. (AUDIO: God of War)

Time in flux
One account suggested that the Ninth Doctor's confrontation with the Dalek known as the Metaltron in 2012 took place in a timeline where the Cult of Skaro "had yet to" emerge from the Sphere and precipitate the Battle of Canary Wharf in 2007 and so did not go on to influence the construction of the Empire State Building, nor was the Earth transported to the Medusa Cascade since the personal timelines of both the Doctor and the Dalek race had not progressed to the point where those events occurred, thus Henry van Statten and most of the human race did not recognise the Daleks at that time. (PROSE: The Time Traveller's Almanac)

Adventures with River Song
When the Tenth Doctor first met River Song, he had no idea who she was, while she seemed to know everything about her. In fact, River was from the Doctor's personal future, (TV: Silence in the Library / Forest of the Dead) becoming a companion to the Eleventh Doctor — and eventually his wife, and as a matter of public record, the woman charged with murdering him. (TV: The Wedding of River Song)

During the crash of the Byzanitum, River Song acknowledged whilst speaking with Father Octavian that she was dealing with the Eleventh Doctor at an earlier point in his time stream, before he learned exactly who she was. (TV: The Time of Angels)



Rewind
During Big Bang Two, the Eleventh Doctor experienced his own time stream "unravelling, erasing" and "closing" as he observed himself in the past. He lived through various scenes from his past, and elected to "skip the rest of the rewind" when he'd reached Amelia Pond's first night waiting for him, shortly after his regeneration. He declared that he "hate[d] repeats". (TV: The Big Bang)

Letters
While awaiting his death at Lake Silencio, the Eleventh Doctor had the Teselecta send letters to Amy Pond and Rory Williams, River Song, Canton Everett Delaware III, and a younger version of himself. He explained that to deliver the messages himself would involve crossing his own time stream. "Best not", he remarked. (TV: The Wedding of River Song)

Trenzalore
The Doctor's time stream later appeared as an open wound in the fabric of reality inside the ruins of the Doctor's TARDIS in the Doctor's future on Trenzalore, where he was buried. The Great Intelligence, in the form of Walter Simeon was accompanied om Trenzalore by the Whisper Men, whom he used to capture several of the Eleventh Doctor's friends, to draw him in so he could invade his time stream. When River Song uttered the Doctor's name, Simeon was able to enter at last. Taking control over the Doctor's history, he turned each of their victories into defeats, as his ultimate revenge.

However, Clara Oswald stopped him by entering the time stream, in order to have her own influence. Scattered across history in countless splinters with their own histories and identities, she helped every incarnation of the Doctor, in order to regain their old successes. (TV: The Name of the Doctor) After failing to kill the Doctor numerous times due to the intervention of Clara's copies, the Intelligence elected to leave the Doctor's timestream to instead attack the Doctor's greatest ally, Alistair Gordon Lethbridge-Stewart, only for Alistair to defeat it. (PROSE: The Forgotten Son)

The original Clara then found herself in a wasteland inhabited by various Doctors. The Eleventh Doctor entered the time stream and was able to extract her. While here, they encountered the War Doctor, and the Eleventh Doctor was forced to recognise the version of himself he'd stricken from memory, who used the Moment to destroy Gallifrey. (TV: The Name of the Doctor)

A new lease of life
Before regenerating, the Eleventh Doctor crossed his own time stream by calling Clara Oswald using the TARDIS telephone. He wanted to remind her that the Twelfth Doctor was still him. He asked about his future self's appearance, wanting to be "anything but old", and Clara confirmed that his hair was grey. (TV: Deep Breath)

Later, attempting to return to the Drum in 2111 from Краснодар in 1980, the Twelfth Doctor found himself half an hour back in time. Watching his earlier self arrive, the Doctor observed to Mason Bennett that he was now locked in his own time stream and so the TARDIS would not let him leave. As such, they had to stay out of sight before time caught up. (TV: Before the Flood)

The Temple of Atropos
During the Great Disruption caused by the First Flux event and the Ravagers, the Thirteenth Doctor took the place of a broken Mouri in the Temple of Atropos and tried to contain the time storm to save her friends who had been forced to take the other broken Mouri’s places. As she did so she was pulled into her own time stream and experienced events of the Siege of Atropos from a life all her memories had been erased of, the Fugitive Doctor. The other Doctor became aware of her future self’s presence and the two conversed briefly, whilst the Fugitive Doctor’s companions put her behaviour down to temporal hazing. (TV: Once, Upon Time)