Derek looked at his arm as Stiles patted him on it and the comment earned a scowl. He was about to smack him upside the head but he moved quickly and Derek would just bide his time and hit him for it later. He pulled the loft door shut and headed after him, stepping into the elevator with him and hitting the button to get them to the ground. He was suddenly very aware that the last time they'd been alone in an elevator, Stiles had been smacking him to wake him up, and Derek had narrowly escaped a punch in the face.
He looked over at Stiles briefly, trying not to think about any of that. They'd emphatically not talked about it, instead only discussing Stiles' father, Derek reassuring Stiles that the Sheriff was fine, that he survived because Stiles was a hero and got to the three of them, and Allison and Isaac, in time to rescue them. He didn't want to talk about Jennifer. He didn't want it thrown in his face again that he'd dated another murderer. Stiles had been distraught at the time, which was why Derek didn't argue back, but it was still a horrible fact to have to think about.
He waited until they were on the ground and the elevator stopped, stepping aside to let Stiles lead the way to his Jeep, before he smacked him firmly across the back of his head, although not as hard as he'd hit him in the past. "You know what that's for," he told him, and then just shoved his hand back into his pocket to follow him.