"I am a bureaucrat and a politician, and magically binding contracts come back to bite you in the arse, because you never get anything for nothing," Percy answered. "You know I'm not that clueless. I didn't make it so far up by being blind, or being too much of a Gryffindor."
He slid even closer, and rested one hand on Cass's cheek. "I'll tell you a secret. Gryffindors wouldn't survive either if they relied on trust. Don't let those houses blind you, Cass. Sure there are some Gryffindors that do trust everyone, but it has more to do with personality than which tower you slept at night while being a child. I don't even trust my family most of the times, so you see, we aren't that different."