His ears are sliding back further into his hair to the point he was clearly getting agitated and his smile disappears all together. His face is that of solid confusion at the question. It's making him think and he doesn't like it. Rage is taking over his features almost instantly and he slides his foot back in a brace like he doesn't want to answer the question. He wants to put some distance between him and Joker.

The other was being a cocky little shit and he wasn't going to take it anymore.

"Shut up," he commands as his hand gives a hard shove of Joker's chest. It's enough to push him back off the railing he was against given how rough and hard he could be when he barely held back his own strength. He had wings. He could fly and pick himself back up. It's the only reason why he does it at all. He wanted it to be made very clear that he could and would kill him if he had the option.