John Hart (Kiss Kiss, Bang Bang)

"Captain John Hart" was an alias adopted by a rogue Time Agent who was an old friend and lover of Jack Harkness. Like Jack, his real name was unknown, the name "John Hart" was an alias he made up after hearing Jack's choice of name. (TV: Kiss Kiss, Bang Bang)

With the Time Agency
Hart was a former partner of Jack Harkness during their time in the Time Agency, both professionally, and sexually. During their time in the Agency, Hart was trapped in a two-week time loop with Jack for a period of five years. While briefly arguing over who the "wife" was in the relationship, Hart agreed that he had been "a good wife, too". He had been in rehab for drink, drugs, sex and even murder. By the time Hart reunited with Jack, the Agency had closed. (TV: Kiss Kiss, Bang Bang)

After the Agency
At some point, John found Jack's younger brother Gray, who, consumed by wrath at Jack for having supposedly abandoned him, had turned against him. (TV: Exit Wounds)

Captain John killed the owner of canisters containing an explosive that latched onto the DNA signature of her killer, thinking that they would lead to an Arcadian diamond. She created a Rift storm and they came through the Cardiff Rift into 2008 Cardiff. He followed them through and asked Torchwood Three to help find these canisters, which he told them were radioactive bombs.

John stole the canisters from under Torchwood's noses, paralysing Gwen Cooper with paralysing lip gloss and wounding Owen Harper. He attempted to kill Jack, but he had become immortal. He sent Ianto Jones off to see if he could save the others and he succeeded.

Finding the last piece on a Blowfish, the contents of the canisters formed into a bomb, and a hologram of the canisters' owner told him the truth about them. Using the DNA of the Torchwood Three crew, John superficially altered his DNA. Jack and Owen were able to save John's life and safely dispose of the bomb before forcing him back through the Rift, but not before he revealed to Jack he had found Gray. (TV: Kiss Kiss, Bang Bang)

Gray used John as an instrument of revenge. He molecularly bonded John's vortex manipulator to the skin on John's wrist and added a Ninth Generation Detonator to it. Gray then threatened to activate the detenator if John did not comply with his plans. (TV: Exit Wounds)

Returning to Cardiff, John planted several bombs in an abandoned warehouse to trick the Torchwood team into being caught in. The team escaped from the rubble, injured but alive. At that point, Jack's vortex manipulator started to beep, revealing John in hologram form, showing that he had Gray. John told Jack he was going to wreak havoc in his world. (TV: Fragments) Later, John lured Jack back to the Hub and killed him. With the others dealing with various aliens in Cardiff, John took Jack, who had came back to life, to 27 AD Cardiff, where he had met Gray. He was then ordered by Gray to bury Jack alive, but refused as he still loved his old friend, but Gray threatened to activate the detonator if he did not comply. Before he filled in the grave he threw a ring, which was really a tracking device, into the hole. John was then set free by Gray. He decided to go back to Torchwood and find Jack to save him, calling it a matter of honour. He was briefly imprisoned by Gray along with Gwen Cooper and Ianto Jones, during which time he sent out a recall signal that stopped a Weevil infestation of Cardiff. After Gray's defeat, and the subsequent deaths of Toshiko Sato and Owen Harper, Hart left the Hub. Jack offered to help pinpoint a Rift event that John could use to return to his own time, but Hart reflected that it might be interesting to explore the world and get a better feel for what Jack found so fascinating about the time period. (TV: Exit Wounds)

John Hart visited Ianto's funeral in 2009, watching from a distance and saying "Take care, Eye Candy". Some time afterwards, John ended up in Mexico, making a living, by buying and selling alien artefacts from a rift off the Gulf. There, he met Beatrice and experienced "love at first sight". However, she stole an old-model vortex manipulator and went after Ianto Jones, two years prior to his death, in an attempt to make him change the timeline. Hart teamed up with Gwen's partner Rhys Williams, as Gwen was now a young mother, and sought out Ianto. (COMIC: Shrouded)

Reputation
At some point John Hart's status as a theif became known to the Bank of Karabraxos. The bank's file on Hart was one of several accessed by Cyborg hacker Psi when attracting the attention of the Teller away from Clara Oswald. (TV: Time Heist)

Personality
Captain John Hart was treacherous and unreliable, to such an extent that Jack Harkness had three rules when dealing with him: the first was never trust anything he said, the second was to always keep him in front of you and the third was to never let him kiss you, which Hart accused Jack of making so he could have his lover all to himself. Hart had amazing physical strength, being able to lift a grown man in one hand and drop him off a roof. Like Jack he was pansexual (possibly even omnisexual, which would explain why, at one point, he took a sudden interest in a poodle) taking a sexual interest in both males and females. He and Jack were once lovers and, according to Jack, John was the wife in their relationship. (TV: Kiss Kiss, Bang Bang)

Although Hart was selfish and treacherous, he was not heartless and genuinely cared for Captain Jack Harkness, turning against Jack's brother Gray as soon as he was freed from Gray's control. He also told Jack that he loved him and the only reason he assisted Gray was because he would get blown up if he didn't. John also felt sorry for Jack after the deaths of Toshiko and Owen. (TV: Exit Wounds)

Behind the scenes

 * James Marsters originally wanted to be in Doctor Who after catching an episode of the new series with his agent, but was cast in Torchwood instead.
 * Marsters has expressed interest in returning as Hart.