Buffy The Vampire Slayer S5 Ep 21 - Gender Transformations

Season 5 Episode 21 The Weight Of The World
Glory finds her body taken over by Ben and after some encouragement from Dawn, Ben takes her and runs. A good distance away from Glory's hideout, Dawn breaks away from Ben and knocks him out with a chain, but this only allows Glory to re-emerge. Ben and Glory battle for control of the body until Glory strikes up a deal: if Ben cooperates in sacrificing Dawn, Glory will ensure that Ben will not die after the ritual is completed, and will grant him immortality and an independent existence away from her. Out of self-preservation, Ben agrees, and hands Dawn over to Glory's minions.