I. Write a scene about something your character did when she/he was a kid, that now she/he is ashamed of.
II. Write a scene for a story, using third-person narration, that opens with your main character having just done something despicable. Despite what he or she has done, find a way in writing the rest of the scene to make your character sympathetic without letting him or her off the hook.
III. Write a story that opens with your main character doing something that is completely antithetical to his or her personality. Let the story be about how this character came to do what he or she did.