Honestly, Bruce is a little scared the whole time, but he's determined to wait it out. He knows Tony, given the choice, would never hurt him, but he also knows how easy it is to give yourself over to uncontrollable, primal urges. His breath hitches when he feels Tony's tongue, but he still doesn't move away, even if a small bit of fear leaps up. In some nightmare part of his mind, he wonders if Tony forgot that he can't feed off Bruce; did Bruce agree to that?

But then Tony stands up again and Bruce relaxes. He smooths his hands up Tony's back, and leans in for a brief kiss, brief only because they should actually talk instead of get distracted.

"How cats feel?"