[Erica feels slightly better that they're keeping something from Stiles as well, but that only means Stiles may be making himself feel better keeping things from her as well.]

I'm glad you got a handle on your wolf.

[That much she means at least, and sounds it. However:]

But if you're going to keep things from me, I want your promise that you will tell me if it becomes necessary. If it's something I need to know? Something I should know, you three can't keep it from me.