[She can tell, from the look on his face that this is bigger than just wrong place/wrong person type of situation. He doesn't just regret it, there's definitely more to it than that.]

I'm glad you told me. [And if this was anyone else she's slept with in the past, she might be annoyed because they were talking about other girls with her. But not with Stiles. They're in this for the long run, she understands how important it is to make things right, to talk it out.]

Whatever happened then, that whole situation you were in. It's over, Stiles. We're changing so many things when we go back. Any regrets or worries you have about it, they won't matter anymore. [They won't exist. Because her deal is for him to never get possessed in the first place.]

That may not even ever happen at all.