An extra bit for the story to sorta give a feel good moment. Lol. Offset the angsty darkness.
Two weeks had passed and they were on their first mission since the so dubbed "Incident". Everyone else had healed up physically, but they were far from fine. What had happened scared them. How Robin had acted. What he'd done.
He hadn't killed the Joker, but he'd been close. So close.
And he'd snapped back to normal as soon as they were rescued. Batman said it was a coping mechanism, like the laughter only...it was more efficient. Robin didn't really remember afterwords. He just knew they'd gotten away and his team had no intention of telling him.
As creepy as his laughter had been the singing...the staring...was far more...disturbing. It was terrifying and inhuman. No child should act like that and if they had a choice between the laughter and...that. They'd take inappropriate laughter any day.
So when the mission backfired and Superboy accidentally set of a bomb in a mostly empty lab and Robin laughed the others joined in. Because now they were in on the joke too.