Merlin took a step back but only because he wanted to be able to duck in case a curse or a fist was soon to be heading this way. He didn't rise to the other boy's words, although he was quietly hurt by them, because he'd seen that fall and it still made no sense. "How did you fall from there and be fine." He was shy at the best of times, but the Gryffindor in him wouldn't let him leave after seeing the older kid fall.