Midoriya lost grip of the situation for the first second when Nensu's hand slipped out of his. But when he felt the chill air from her arm, he perfectly understood the situation. And he knew he had to stop it no matter what. Losing her cool was not good for Nensu. He bolted forward and reached for her shoulder, turning her towards him while putting himself between the two. If he was standing closer to her than Endeavor, she wouldn't attack the hero in a frenzy so easily. If not... well, he'd have to wish for the best of his luck.
"STOP!"
He yelled at the two.

Hiems suppressed the urge to jump out and help ease the situation. It was a fight of emotion, where he had no place however he looked at it. He had to let Midoriya completely deal with it. Trust the heart of gold he had. 'Or I could silently slither to the faculty.' He thought. That was tempting. If someone like All Might could come the situation would be finished quickly. One way or another.