Derek's eyebrows lifted with interest when Elsa cut herself off. He was patient, though; he didn't prompt her to continue, he just waited for her to do it on her own. What he wasn't expecting was to hear that she had some sort of mutant abilities. Latent, like his own, or deleted perhaps; he wasn't really sure how that all worked.

"But you can't do it now?" he asked. "Whatever, the ice thing? You could do it home but you can't do it now while you're here?"

Because that's a thing Derek's been struggling with. Elsa might have been happy about it for her own part, but Derek felt slow and weak and he hated being fragile. He missed being a werewolf.