I figured out how to phrase it: S-girl didn't have exuberance. She had a pretty hard shell around her, and I took it upon myself to poke her out of it.
You know she could go a whole day without laughing out loud? I mean, why would you do that? Tsk, tsk. I would understand if she just didn't see anything funny, but I'd see her just sorta suppress it and swallow her laugh.
Not on my watch!