"Maybe I wasn't," Derek shot back, and then immediately regretted it.
He hadn't meant to say that. At all. To anyone. Much less to Allison.
It was the truth, though. Despite everything...the werewolf was happier now with Stiles than he had been before. Taking care of Stiles fulfilled a need that taking care of Isaac couldn't, simply by virtue of Stiles being human. Stiles needed him in a way the werewolf didn't.