Yuya tries to pull away at first, done with being manhandled for now. He wants to see if he can do something to help them get out, first, since Peridot's friend is in danger.

Then she transforms into a huge dragon, and Yuya has to press against the wall so he doesn't get squished between Gongenzaka and Peridot in their ice cage. And then, well, he did ask about the fire but he didn't expect her attempt to be so uncontrolled, and neither Yuya or Gon have any natural resistance to that.

So he yelps and tries to duck away, panicking as he feels the heat come close. "Stop, don't set us on fire!"