Rhona Mitra & Robert Baker Cast in Supergirl

Deadline is reporting that The CW has cast Rhona Mitra and Robert Baker as brother and sister Mercy and Otis Graves in the upcoming season of Supergirl. Mercy is Lex Luthor's bodyguard in the comics and in the show has picked up Lex and Lillian's agenda after they were both imprisoned. Otis acts as Mercy's right-hand man and possesses "savant-like abilities to assassinate aliens." Both characters will recur throughout season four.