Damian and the Teen Titans had nearly been killed by King Robin's super robot back then.
But now that Deathstroke had disguised himself as King Robin, he did not mind at all. In fact, he found it rather amusing.
Being able to act alongside his biological father, enter the battlefield shoulder to shoulder, slaughter some hideously ugly monsters together, and listen to his father tell dry jokes amid a sea of blood—this was Damian's ideal father-son activity.
Those past operations with Batwoman did not count. He had been deceived by that guy; she was not his father at all.
If not for avoiding becoming the fuse that ignited a Justice League civil war, Damian would have wanted to change his surname from Wayne to Wilson long ago.
The boy had grown up in the League of Assassins and had been trained as a killer by his mother and grandfather. He did not reject killing in his heart—he even liked it a little. And clearly, Deathstroke was one of the finest killing experts around.
Just think about it. If his parents were killers, his grandfather was a killer, and he himself was a killer, what a happy family that would be. They could even make a family sitcom out of it.
"Robin, go stop the Slaughter Beast encirclement from closing in! Hahahahahaha!"
Deathstroke, thoroughly immersed in his role, gave the order for the boy to disrupt the monsters' pincer attack and keep everyone from being surrounded.
"Got it, hee hee!"
Damian rarely used methods that involved impersonating others, but that did not mean he could not act. He got into character as well and answered with a strange laugh.
Looking over the battlefield, in a situation like this, it was time to use that!
Before the enemies surged in like a