I think should be added the scene of Mad Love when Batman was almost to being killed by Harley Quinn, but he saved himself by convincing her that The Joker would have never belived she actually killed his nemesis unless he had seen it by his own eyes.
So she called the Joker to show him what she has done. But, as Batman foresaw, The Joker didn't appreciate it as much as she expected.
I think should be added the scene of Mad Love when Batman was almost to being killed by Harley Quinn, but he saved himself by convincing her that The Joker would have never belived she actually killed his nemesis unless he had seen it by his own eyes. So she called the Joker to show him what she has done. But, as Batman foresaw, The Joker didn't appreciate it as much as she expected.