Over the decades, many avid comic book fans have wondered whether the Joker knows Batman's identity. It's a plot point that's driven several comic book debates, with some fans thinking it'd ruin the mystique behind their rivalry. Others believe it'd add more nuance, fully explaining why the Clown Prince of Crime always comes after Bruce Wayne's loved ones.
Source：https://www.cbr.com/knight-terrors-joker-batman-identity-bruce-wayne/
