In Arkham Asylum, it was implied that you were battling for control of your mind, IE: If you lost, you went completely insane
In Arkham Knight, he used a much stronger variant of Fear Toxin, which drove people to strike out at each other, and also just harmed them in general, so presumably it's a mix of Crane and the Toxin hurting them
Because that's how she looks in the comics.
Ed Boon says next Injustice 2 DLC will include the most “unexpected character” https://t.co/IrCCrTAFBi pic.twitter.com/RbmmasTlrb
— Shoryuken.com (@shoryukendotcom) July 25, 2017
Those are all things she's talked about in the show.