Buffy sees that shift in expression and she's curious about it. She knows so little about Derek's life back home. They tend to focus more on things here.

She nods a little at Allison's question. "He's my room mate. Things were a little rocky at first. I don't think he liked me much, but I've won him over."

"You've got magic though?" She's curious about what kind and what it does. If they could get any form of it here, they might be able to at least make life a little better if not get out of here.