Carys Fletcher

Carys Fletcher was a Cardiff girl in her late teens or early twenties living at home with her father, until the sex gas possessed her.

Biography
One evening during a club, after splitting up with her boyfriend, Eddie Gwynne, the sex gas entered into Carys's body and used her as its vessel. Taken over by it and now able to generate powerful pheromones, she seduced and killed a young man at the club named Matt. The gas fed by stimulating its victims to the point of orgasm, at which stage their bodies exploded into dust.

Torchwood 3 captured her with a portable prison cell and took her back to the Hub for questioning. Gwen Cooper attempted to talk to her, but was seduced by the pheromones and made out with Carys until the sex gas realised that it needed men. Later, she persuaded Owen Harper (again by seducing him) to release her. She eventually killed her ex-boyfriend, as well as several clients at the sperm bank where she worked, before Torchwood caught up with her again. After the team managed to separate the gas from Carys, they took her home to her father. She was then able to return to her previous life, seemingly with no or hazy memories of the events that the possession had caused. (TW: Day One)