Captain Jack Harkness

Captain Jack Harkness is a fictional character in the British television series "Doctor Who" and "Torchwood". He is played by actor John Barrowman. He was first in "Doctor Who" in the 2005 episode "The Empty Child" and is in the show throughout the rest of the 2005 series as a companion of the Ninth Doctor. Jack later becomes the main character in "Torchwood", an adult-themed spin-off of "Doctor Who". He comes back into "Doctor Who" in the 2007 series and he meets the Tenth Doctor, and returned again for the 2008 series.
Jack is a time traveller and former conman from the 51st century. A bisexual. In contrast to the wiser and older Doctor, Jack prefers a hands-on solution to the problem at hand. As a consequence of his death and being brought back in the last episode of the 2005 series of "Doctor Who", the character becomes immortal, which does not change during both "Doctor Who" and "Torchwood".
Characterisation.
 In naming the character, executive producer and head writer Russell T Davies got inspiration from the Marvel Comics character Agatha Harkness, Jack's original appearances in "Doctor Who" were thought of with the intention of forming a character arc in which Jack is changed from a coward to a hero, and John Barrowman consciously minded this in his portrayal of the character. Following on that arc, the character's debut episode would leave his morality as ambiguous, publicity materials asking, "Is he a force for good or ill?"
The character is described as both "lethally charming... good looking and utterly captivating", as well as "flirtatious, cunning, clever and a bit of an action man". Within "Doctor Who", Jack's personality is light-hearted, although this changes in "Torchwood"'s first series, where he becomes a darker character. In "Torchwood" Series 1, Jack has been shaped by his ongoing search for the Doctor and also by his role as a leader, in which he is predominantly more aloof. During The second series of "Torchwood", Jack became a much more light-hearted character once again, after appearances in "Doctor Who" where he was reunited with the Doctor.
From the Torchwood onwards, Harkness wears period military clothes from the second World War, including braces and an officer's wool greatcoat in every appearance. Costume designer Ray Holman comments that "We always wanted to keep the World War Two hero look for him, so all his outfits have a 1940s flavor. We knew he'd be running around a lot, so I redesigned his RAF Group Captain's greatcoat from "Doctor Who" to make it more fluid, because the real things are very weighty... The rest of Jack's costumes are loosely wartime based, so he has big wartime trousers which are getting more and more styled to suit his figure. There are actually five Captain Jack coats used on the show - one hero version which is used for most scenes, one wetcoat made with a pre-shrunk fabric, a running coat which is slightly shorter so John's heels do not catch when he runs and two stunt coats - which were 'hero coats' back in Series 1."
Discussing whether his character could ever find a soulmate, John Barrowman refutes that Jack "likes everybody, and his love for each person is different". He believes that Jack does harbour romantic feelings toward the Doctor, but "would never take that beyond infatuation" and "would never let the Doctor know". Barrowman describes Jack's love for Ianto as "lustful", and if he ever were to settle down with him, he would "let Ianto know that he [Jack] has to play around on the side". John Barrowman and Gareth David-Lloyd have also opined that Jack's relationship with Ianto has however brought out Jack's empathy, and helped to ground him. In contrast, if he settled down with Gwen, "he'd have to commit completely" to her; this is why he does not act on his feelings for her, because even though she would let him flirt with other people, he could "never afford to do anything more Eve Myles, who portrays Gwen, describes theirs as a "palpable love" and opines that "with Jack and Gwen, it’s the real thing and they’re going to make you wait for that." "Torchwood" Series Two sees Jack promise both Gwen and Ianto that they were the reason he returned to Cardiff. Barrowman claims that Jack also "fancies" fellow companion Martha Jones, admiring her "tenacity" and willingness to "spat with him", and describes Jack's love for Toshiko and Owen as "fatherly", stating "He was guiding them. That's why it was so devastating for him to lose them." Offering reasons why Jack could never find "The One", Barrowman brings up the character's immortality. "He always loses them. He outlives them. They die. He watches them get old. That bothered him in Series One [of "Torchwood"], but now he's come to terms with that, I think... so now he just sleeps around!"
In several instances in "Torchwood", Jack displays no problems with killing a person of any species, which within "Doctor Who", allows Jack's character to act in ways the lead character cannot. When reuniting with the Doctor in the 2007 series, he is verbally warned "don't you dare" when pointing a gun. Witnessing the murder of his colleague Owen, Jack shoots his killer in the forehead, killing him in an act of quick revenge. Whilst the Doctor scorns Jack for joining the Torchwood Institute (an organisation he perceives as xenophobic and aggressive), Jack maintains that he reformed the Institute in the Doctor's image; Jack himself had initially been critical of the moral failings of a 19th-century Torchwood.