Josh Davidson is Detective Kate Beckett's ex-boyfriend from Season 3. He is a cardiac surgeon who, like Beckett, rides a motorcycle. He first appears in "Punked" when he drops by the precinct. Unlike with her last boyfriend, detective Tom Demming, this relationship takes not only Castle, but all of Beckett's colleagues at the precinct by surprise, since she never mentioned having a boyfriend prior to Josh's showing up at the precinct.