>>125098119I don't really care that this probably isn't someone from DC, but:
1. Since there's a lot of those grungier, grittier stories going around, she could be the villain in a Batman story where basically she's going around pretending to be an innocent kid so creeps and weirdos would attempt to rape/kidnap her, whereas then she flips the tables on them and puts them through gruesome sexual torture, jamming literal toys up their asses or whatever, or just kills them outright. Batman being Batman doesn't like that anyone else is going around killing people, even if they deserve it, so he does his usual detective work to find her. The plot can either go the route where she's punishing people for less and less severe crimes until she's murdering them for looking at her funny, or the plot can go more straight-laced and just have a bit of that "if she's killing bad people, is it really so bad?" thing some plots do, but then Batman gets some flashbacks about suffering as a kid and yadda yadda.
2. Team up with literally any of the kid/toy villains out there.
3. Temp team-up with Batman to root out a pedo cult/ring.
4. She has a kid, and the kid has a genetic disorder that makes them age faster, dying in a week, despite Bruce Wayne's efforts. Ends either sadly, or with her going into a flying rage aimed at Wayne Enterprises.
Also I think it'd be funny if somehow there could be a story about her getting hired by a Japanese company to work as an actress for a live action show and she plays as a "looks like a kid but is actually a million years old" character. No clue how to turn that into a Batman plot, I guess, unless maybe another Batman villain decides to use her leaving Gotham as a tricky plot, where they stuff a nuke into her doll and Batman has to follow her to Japan to try to deactivate it before it nukes Japan for a third time.
