(WARNING!!! Spoilers Follow)
Gwen Cooper is recruited into Torchwood after a police investigation crosses paths with Torchwood. She takes a while to get used to the idea of Torchwood and their methods, having been used to the straight and narrow of the police force. But she soon grows used to the team and learns to love the work.
Her personal life takes some turns throughout her association with Torchwood, but she holds tight to it, despite the rest of her team not even attempting a personal relationship...