I guess, a character must not be only one thing. it can't be only good or only bad, only right or only wrong, only sad or only happy. In other words, it can't be only one note, it has to be a song, if not a symphony. For example, I like to make the hero very flawed and the antagonist the bearer of wise and true messages. It creates a natural conflict and it's a premise full of irony and humor possibilites.