Emma smiled. Izzy was grinning, teasing a little again, Emma thought.

“Tell me,” Izzy said, sounding interested.

“All right,” Emma said. “Have you ever had the feeling that someone you’re having sex with is actually, at the same time, having sex with their ex?”

“Imagining them, you mean?”

Emma shook her head. “Not like that. Not on purpose, and not to be cruel to you. Just… doing what that other person used to like them to do, I suppose I mean. And doing it subconsciously, completely without meaning to. Forgetting who you are, I guess, and going back to old habits they had with someone else. And not realizing they are, because they’re distracted by having sex. So they’re half-expecting you to respond how the other person would, doing that thing they really liked to do, rather than remembering its you they’re with right now.”