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"<nowiki>'</nowiki>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.