Hiccup recognized that stutter, the sound of someone trying to avoid talking about something. He'd made it more than a few times himself. And he had a fairly good idea of what Zuko was trying to not talk about.

"You might as well tell me why. I promise I won't bite your head off even if it is I think it is. With what my people gave done, I don't have much of a leg to stand on." Hiccup raised his peg-leg for effect.