Buffy The Vampire Slayer S04E16

Who Are You (Part 2)

Buffy (in Faith's body) is abducted by the Council's team, while Faith (in Buffy's body) has ruthless fun at the expense of Buffy. After Faith and Buffy (as each other) rescue a group of people in a church that has been attacked by vampires, they switch their bodies back. Faith begins to feel remorse, and heads to L.A.