[Prefect slumped back, frowning.]

It is related to trust. The reason why you lie to someone is because you're afraid of how they'll respond to the truth. If... someone trusted me when I said that they weren't going to get in any more trouble for telling me what they'd done? And that maybe it would actually end up better for them? Then they wouldn't need to lie about it.

[He missed that 'working out' bit, Barron. You get a temporary reprieve from being freaked out at over it.]