"A description would help a lot. We don't actually know too much about who is on the other side."

Nightwing came in uniform. Mostly because Dick Grayson wouldn't be a friendly face to the boy. Probably wouldn't, anyway. He had no idea how much he'd been around the Titans while Blue Beetle was a member, but he doubted that he was quite close enough to the boy to be on an unmasked face basis with him. So, he arrived in uniform with domino in place. It was likely to be more comfortable.