Well... certainly wasn't expecting this. As stated before, Damian is the son of Batman and Talia al Ghul, and raised in the League of Assassins until he was dumped onto Bruce Wayne. Mar'i Grayson, however, is the Earth-22 daughter of Dick Grayson/Nightwing and Koriand'r/Starfire (her superhero name is literally a ship name and that is amazing).
There's not a whole lot to go on since, technically, these two have never met. Plus, as far as I know, while Nightwing and Starfire were dating by the time Damian showed up, they weren't in the baby-making phase yet. So if Mar'i did become canon in the main universe, Damian would be a decade or so older than her. And that's a little weird. But this is just as far as I know, so don't get too mad if I got something wrong.
However, after some more digging, I found out that Nightstar was married... to a guy named Ibn al Xu'ffasch, which is basically Earth-22's version of Damian Wayne. And that's pretty cool.
While I don't necessarily ship it, it is a pretty neat dynamic, if not a bit weird (seriously, Damian's her adoptive uncle... you cannot tell me that's not the least bit weird). I will not falter from my Damirae shipping path, but it's cool to see this canon in another universe.
