On the TV show Dexter, the actor who plays Dexter is married to his on-screen 'sister'.

Co-stars Michael C. Hall and Jennifer Carpenter were married on New Year’s Eve 2009 at an outdoor ceremony in Big Sur, CA. The couple met 3 years ago during the first season of the series, but had been quietly dating for at least a few months prior. Ironically this followed the season 3 finale, in which Hall (Dexter) was married to his onscreen fiancée.