Owen Harper is easy—he’s such an Aries. Charges his way through life without thinking of the consequences. He is very much a fire sign. Not Leo, because he doesn’t care if people like him. Not a Sagittarius, because he doesn’t have the philosophical attitude toward life.
Gwen is also pretty obvious: Leo. Gwen wants to be liked, wants attention, and yeah, she has that passion.
Toshiko requires a bit of thinking, but I’m quite sure she’s a Pisces. Pisces are very sensitive to emotions. Something tripped me up for a moment: Pisces are supposed to be creative. Tosh is a tech person—not something you typically associate with creativity. And then I remembered her origin in Fragments: She’s also a brilliant inventor, something you definitely need creativity for. Tosh may not be a traditional Pisces, but it’s definitely her sign.
Jack I also had to think about. He has some Sagittarius traits, some Scorpio traits, so many Leo traits that I might define him as Leo if I was exclusively dealing with his Doctor Who characterization. Counting Torchwood canon, I named him Capricorn. Because he likes to be liked, but it’s not essential to his being. Because he is this steely thread of determination that runs through everything he does. This is a man who waited over a hundred years for the Doctor, who lived life on earth to the fullest while never losing sight of his original goal, ready to drop everything in an instant. I think he is a Capricorn: Ambitious, determined, sensual.
And then there is Ianto. Such a classic Virgo in his neatness, and such a classic Scorpio in his secretiveness. I just can’t make up my mind.