She does show up elsewhere in the series. She... she steals. After she takes her opponents out, she liberates their money. Always a big roll of bills in the art. That's why I said she wasn't heroic, but Batman is unheroic in this comic too. She's certainly not unlikeable, though, I like her in this scene and a few other panels I found the best, and she's definitely unique in this comic.
Hadn't thought about the Monaghan link, but it's a possibility.