Well, people can catch you by surprise. I'd compare it to someone standing in the middle of camp and hollering.

[ Dark caught the lot of them off-guard at an odd hour, so it wasn't all that much about being willing or not. ]

As for cutting someone off — that's more like shutting a door. If you decide you're done, you're done. It makes more sense in practice.

[ Shutting people out or cutting off communication was fairly intuitive, odd as it seemed at first. ]