Planet Z's embodiment of the concepts of tragedy, Donna is a pathetic little demon who's such a loser that her only assignment is to annoy one single dufus on Planet Z, and she can't even do that right! While Fritz is a carefree soul with a bad habit of causing unintentional destruction, Donna is a mean-spirited little monster who couldn't instigate chaos if her life depended on it. She's not allowed to return to Hell until she manages to kill Fritz or at least sink him into an inconsolable depression. And with her poor record and his happy-go-lucky attitude, that's going to take a while... Which was precisely the point.