Duncan B.

 was a middle-aged man living in Cardiff. He had a wife, Maddy, and a son, Stephen.

Suffering from a midlife crisis, he started drinking and flirting with other women using a dating app. His encounter with Dawn Shale left him infected with a parasite, which forced him to seek more sexual encounters. In particular, he infected Jack Harkness and killed him. He had enough self-control not to go near his home so as not to infect his family. Torchwood Three brought him to the Hub, cured him using worms provided by the Sorvix and gave him retcon. (AUDIO: Love Rat)

Nevertheless, his escapades led to a financially contentious divorce with Maddy, forcing him to sign a lease for the Ritz Tower. Not to be thrown out, he was forced to help Bilis Manger to get rid of the body of Amber and to shoot a gun at St John Colchester and his husband Colin Colchester-Price to prevent their escape from a dinner party by the stairs. (AUDIO: A Kill to a View)