Isaac opened his mouth to Derek's advances, letting himself be used that way, just as Stiles had used his ass. The satisfaction was so bone deep, he was barely comprehending the circumstances of it all any more. The pressure of Isaac's body against Stiles' seemed to be the only thing keeping them upright. Even though it hadn't been his ass that Derek had come in, which was in itself an odd feeling, Isaac did as he always did.
"Thank you, Master," he said, his speech slurring. He bumped his shoulder forward, prompting Stiles to do the same.