"You'll have to refresh my memory," Derek replied, dryly. "I could think of a few things that fit that description. Now, kneel. I'm not going to ask again."
It wasn't a threat. It was a statement. Stiles was obviously pissed, but Derek wasn't going to put up with his insubordination. The problem was that the last thing that Derek wanted to do was punish the boy, though he desperately needed to be disciplined, and he honestly had no idea how to discipline him without resorting to physical violence.