Damian did not concern himself, on principle, with rivalries with anyone not on his skill level. It would be a waste of time and energy to indulge in every commoner that had a problem with him.
You, however, had been an exception. From the very beginning you two had not gotten along. Since that god forsaken charity gala your parents took you to and promptly set you loose in.
They’d been talking to Bruce as they yammered on about child care (they had a nanny and didn’t actually raise you) and how cute Damian was and how well adjusted Bruce’s children were. Damian could laugh if it weren’t abhorrently untrue.
You, simply, were a brat seeking attention. That meant pretending Damian had hit you or had said something rude and every time you’d come crying to your mom or dad. Every time they’d ignore you and move on. Despite this, you persisted.
As Robin, he picked on you and was able to get away with it. That night should have been the same. He and Bruce should have gotten there on time. They should have stopped the shooter before he mugged your parents and promptly executed them in front of you.
The police had you in a thermal blanket sitting in the ambulance, a vacant look on your face that made Damian’s stomach churn. Of course, Bruce felt worst of all. The day of their funeral, all the Wayne’s got ready to be there for you. There were plenty of people there, but none of them knew your parents like they had. No one knew you like Damian did.
You were standing there, in your black funeral wear. Staring at the two caskets of your mother and father while your Butler held an umbrella over you to shield you from the rain. Bruce nudged Damian closer to console you and against his better judgment, he did.