Harley Quinn:
After finding out the the Joker was killed (not really, she just thinks the Batman killed him) she goes crazy and starts destroying the city. Towards the middle of the film, unites forces with Poison Ivy, and they both go after Batman.
We get introduced to a young Barbara Gordon, who thinks Batman might need some help and does her best to aid him. She gets introduce to the Bat's world but she doesn't become Batgirl just yet.
