I've got a character concept in mind to that effect: Basically just a low level crook who, during all the chaos, basically grabbed all the shit he could from Arkham's storage and made tracks. A suit made out of pieces of other super suits: Patchwork.

A possible issue with the Patchwork concept is that Arkham may have been wholly destroyed. It is possible that Arkham Island may be the version in this game, thus it could possibly have been out of range of Jokers' bombing, or he could've rushed there early on. But I find the timeline being a problem, because it would make your character very old, assuming the game would have a fifty year timeframe or anything like that like in Old Man Logan. Plus, the villains probably would've killed him, rising to power and all.

Not saying it's a bad idea. But just a few things to think about.

Edit: I hold no authority

Edit 2: I have nothing against old people nor do I know the details of the timeline

I mean, he'd be... REALLY old. Or at least, that was my thought.

Well I mean, Luthor's deal was before the dirty bomb, yes? So prior to Gotham's destruction, there was SOME warning that bad stuff was going down.

Looks interesting, I hope I have time to commit.