Tough question. What would it feel like if he started changing back? Would it happen in a blink? Would he lose feeling in his limbs and fall over? Would the transformation be slow and painful, like that one movie he saw with Chara about a human turning into a fly? (Not that he thought being a fly is bad, since plenty of fly monsters lived Underground. The body horror and vomiting looked painful though)

"I don't know. I'm... fine? But I'm not sure if it means anything."