[ even in the dark he can recognize that voice, and he shouldn't have been surprised about there being more people from his world, but Furina was definitely not one he'd been expecting. the last time he remembered seeing her was ... well. definitely before he'd been imprisoned. everything after he was a little fuzzy on. ]

Why if it isn't little Miss Hydro Archon.

[ he hadn't been changing before, but he moves to do so now. it's dark enough, why not? ]

Judging from your surprise I guess it's safe to rule out this being your doing. A shame - I think this would have been quite the interesting punishment to criminals like me.