James.
He seemed polite? Yeah. He does that. He manipulates and twists his way around people. That's what he does. Did you know that in our third year, he tried to have Hagrid fired because of an accident in class? Instead he managed to nearly get an innocent animal offed for attacking him. And the attack wasn't even as severe as he said it was. He was barely scratched and he might as well have been walking around Hogwarts looking like a bloody mummy with all the bandages he had on. And that's only one small story among many. Don't get me started. You don't know him.