Leo doesn't know what's happening as it does, but he can't call out in the moment, winded by the pain and the strange feeling of his body changing rapidly. It's only after it's over, as he curls over his knees, panting, that he finds his voice again.

"I... I dunno. That's never happened before."

He gives his head a shake, the new locks fluttering around him, and then looks up at Donnie - only to frown and lean back when he sees his brother's expression.

"What's wrong?" he asks, hesitant, like he doesn't really want to know.