Despite Toothless' attempt to show how docile and friendly he was, Heero still didn't reach out and touch the dragon. It didn't have anything to do with thinking he was dangerous anymore. The largest animal he had ever dealt with was a horse, which was trained, so he was a little bit scared to touch something that build wise was bigger than that. A lot bigger and stronger than a horse.

He looked back to Duo once the dragon ignored him and watched as Toothless tried to cheer him up. It was a bit amusing to watch it interact with the older pilot. Duo looked like he could fall over any moment and yet this dragon kept nudging him and acting much like a cat would.