Batman: White Knight stopped with a fist, i.e. Batman's methods. This led him to turn the Joker into a politician, using the character's intelligence and charisma to win the people of Gotham over. DC Comics had no problems with the ideas that Murphy had for the series such as changing the timeline in Batman's history. However, the adult content like nudity and profanity that Murphy had intended to include were not permitted. Murphy revealed that the Joker in "White Knight" has the real name Jack Napier, a callback to Tim Burton's 1989 "Batman" film where the Joker played by Jack Nicholson also shares
Batman: Under the Red Hood to kill the Joker but will not, fearing he will not stop if he kills once. Jason tosses Batman a gun and gives him an ultimatum—he will execute the Joker unless Batman shoots Jason. Batman refuses and drops the gun, causing Jason to shoot at him. Batman throws a batarang, which mangles Jason's hand. Defeated, Jason sets off a time bomb and Batman subdues the Joker before attempting to save Jason. The bomb explodes; Batman and the Joker survive but Jason is gone. The Joker is returned to Arkham and Black Mask is arrested for his involvement in the Joker's