Describe Sister’s personality. Is she slightly crazy or is her odd behavior a justified revolt against her family?

Sister is odd, but I wouldn't say she's crazy. Unfortunately, she is mean, petty, jealous, and manipulative. Whether or not Sister's feelings and actions are justified is questionable, as it seems she has a lot to do with the way things turn out. In the end, we just don't seem to feel as if Sister has been driven out, as much as she's been doing the driving.