Spoiler: If the Princess enters his home, Bardo spots her and asks if she is a thief. No matter how she answers him, Bardo tells her that he has misplaced the key to a cabinet in his cellar and asks for her assistance in opening it. If the princess agrees, he will lead her to the cellar. The cabinet is there, along with the corpses of Bardo's previous victims. Bardo blocks off the princess's escape by locking the doors and transforms into a werewolf. The princess must kill him to retrieve the key to the doors.
If the princess has already seen the corpses in his cellar before speaking to him and tells him of this, he will attack her.