I'd say, do this
She is made D.A......... she hires a new lawyer named harvey Dent...... later in the movie, her and Bruce develop more of a relationship, but the Joker soon finds out that Bruce Wayne is indeed The Batman, obsessed with destroying him, he kidnaps Rachel, and eventaully kills her...... this drives The Batman over the edge, hunts down the Joker, after some events, Batman has the Joker, and is ready to kill him, he has a flash back of her saying (it's what you do that defines who you are), so he decides to bring the Joker in instead of killing him, sets up the 3rd movie where the Joker is put on Trail, Harvey Dent then becomes the D.A. of Gothem.......