Hythlodaeus folds his arms, giving the Joker a flat look. Alright, he's going to assume this is some kind of ruse- an act. So he'll keep out of the way, for now... even though Emet-Selch would not like this one bit, even if it isn't real.

For what it's worth, the guy looks like he might apologise- he wrinkles his nose at Hythlodaeus as if in thought. Then he laughs. Not happening, buddy. Tell it to get out of my way next time. Train it better.

And he pats Joker on the shoulder condescendingly and turns to go on his merry way. Hythlodaeus gets the impression that was the entirely wrong thing to do, but perhaps the man feels safe in knowing that there are plenty of others around and that it's broad daylight; it feels a lot like dancing with danger regardless, though.