Costume pretends to be something he's not, constantly putting on horrible disguises to trick people. Costume has a never ending hunger, so he kills for a good reason, not that he's evil. His disguise is only a mask, though, it does mess with him mentally if worn for too long. He slowly changes his personality to fit the character he was supposed to pretend to be, to the point where he starts to think he IS that character. Fun Fact: Costume is a smart, predatory animal. So when he hunts (like I said earlier) for food, not to harm anyone for fun.
This is a halloween thing now, happy halloween
