Batman got shot and you were furious. Batman told you not to do anything about the situation. “You’ll be just as bad as him..” he’d tell you.

You did so anyways. You beat the Joker, along side you Harley. You both beat him to the core. Harley was really taking everything out. You wanted to teach him a lesson.

You didn’t kill him since you knew Batman didn’t believe in death.. or whatever. Suddenly Nightwing opened the doors to the warehouse Batman sent him. He was also on his way.