Damian was a little better behaved at the start of the party mostly because Dick's hosting and he doesn't want to get the frowns and sighs at the outset. He kept track of who attended (because he's a bat) and happily introduced pets to all the party goers. Probably made a few bits of small talk too, pointing out that the vegetarian options were surprisingly decent.
Totally was not down with engaging with anyone asking inane questions or overly treating him like a little kid. Towards the end of the party, he probably found some quiet corner and spent the rest of the time fiddling with his phone. Socialization can be draining, okay?