John Hart ( Kiss Kiss , Bang Bang ) " Captain John Hart " was an alias adopted by a rogue Time Agent after hearing his friend and lover Jack Harkness ' s choice of name . ( TV : " Kiss Kiss , Bang Bang " ) Biography . 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 " . ( TV : " Kiss Kiss , Bang Bang " ) On another occasion , the two time agents faced off against a hoard of Weeping Angel s . After two years of Jack ' s memory had been erased , John and other Time Agents refused to discuss it with him . ( COMIC : " Secret Agent Man " ) He had been in rehab for drink , drugs , sex and even murder . By the time that 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 detonator 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 Mairwyn who introduced her self as " 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 " ) In 2016 Hart turned up at Torchwood House . He shot James Stirling III and stole the Astrolabe . ( COMIC : " World Without End " ) After helping Torchwood defeat the Navigator s , John stole Karina Stirling ' s TARDIS . ( COMIC : " Station Zero " ) Reputation . At some point John Hart ' s status as a thief became known to the Bank of Karabraxos . The bank ' s file on Hart was one of several accessed by augmented human 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 omnisexual , taking a sexual interest in both males and females , and , once , even a poodle , which he found " gorgeous " . 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 " )