Jack Harkness (Captain Jack Harkness)

Captain Jack was a young American serving as an RAF Group Captain stationed in Cardiff. The episode revealed that he was trapped in a heterosexual relationship, and he was eventually revealed to be gay and distressed at the idea that his girlfriend might actually be in love with him, unhappy to lead her on. After some indecision, and after Torchwood's Jack (who adopted the assumed name of Captain James Harper after Captain Jack first introduced himself) hinted that he would die soon, he eventually struck up the courage to dance with Torchwood's Jack in front of a party of servicemen and their guests. Before Torchwood's Jack left to return to the present, the two kissed passionately, leaving both in tears. The next day, Captain ack Harkness died fighting German fighters. In the present day, Toshiko Sato comforted Torchwood's Jack by telling him that 1941's Captain Jack would be proud that he took his name, carrying it on as he saves the world.

Con man Jack Harkness (birth name unknown), who had served during World War Two, had assumed the original Captain Jack's identity after his death, prior to his first appearance in the Doctor Who episode The Empty Child. At that point in his personal timeline, he had not met the original Jack or joined the Torchwood Institute. Therefore, he knew of the original Jack's fate before he met him, but was not aware of what he looked like.

1941's Captain Jack is identified as of the same rank as Torchwood's Jack. This could reflect a misunderstanding of the RAF rank structure by the writers, since he only commanded a squadron, and Group Captains are never addressed or referred to as "Captain".