WARNING: The following contains spoilers for Batman: Three Jokers #3, by Geoff Johns, Jason Fabok, Brad Anderson and Rob Leigh, on sale now.
Among other things, Batman: Three Jokers explained why the Joker seems to have gone through so many different iterations over his life by introducing three characters who all served as the Joker.: the Criminal, the Comedian, and the Clown. And in the three-issue miniseries, these Jokers tried to make another Joker in their image by turning Joe Chill, the man who murdered Thomas and Martha Wayne many years ago and turn him into a new Joker.
Chill was only the latest person they tried to turn into a new Joker after a string of failures. However, as Comedian Joker revealed in Batman: Three Jokers #3, this was all part of his plan to make Batman forgive Joe Chill so that he could take the spot of the Caped Crusader's greatest enemy.
The Criminal Joker had a different plan. He felt that Joe Chill would be the perfect new Joker since he was the man that meant more to Batman than any other enemy in history. This much was true, at least before this series. Joe Chill killed Thomas and Martha Wayne, and that is what sent Batman on his journey to become one of the most effective vigilantes in the world, with only cleaning up the streets of criminals his only goal and desire. Batman wouldn't stand for turning Joe Chill into a fourth Joker because Batman wanted to save the man.
Before arriving at the Monarch Theater to face Joker, Batman visited Chill's room and found all the letters the man had written to apologize for what he had done. Chill even admitted that he killed Thomas and Martha because he considered them the same people who held the poor down in Gotham City. When he discovered that he killed two of the people who were trying to help the poor, Chill realized he made a drastic mistake and began his road to repentance. He never sent the letters to Wayne, and this was Batman's first time seeing them.
When Joker finally chose to drop Chill into the vat of acid to change him, Batman swept down and saved him. Comedian Joker reveals this was his plan. Now that Batman has forgiven the man who killed his parents, there can be no villain that is Batman's greatest pain than Joker, the man who "healed" Batman's greatest wound.
This isn't the first time that DC has addressed Joe Chill and Batman's relationship. In 2008, "Joe Chill in Hell" played out in Batman #673 by Grant Morrison, Tony S. Daniel, Jonathan Glapion, Sandu Florea, Guy Major, and Steve Wands. In this issue, Batman is hallucinating after the Bat-Devil shoots him, and he sees Chill as a mid-level crime boss. In the hallucination, he gives Chill the gun that killed his parents, and when the criminal realizes he created Batman, he is presumed to take his own life. In The Dark Knight Returns, Batman comes across two criminals who try to kill him, and he realized, looking back, that Joe Chill wasn't evil, but he was someone who wanted money and was sick and guilty and forgave him.
However, in Batman: Three Jokers, the series had a Joe Chill ending that finally seemed perfect. Joe Chill apologized for killing Bruce Wayne's parents. He wanted to die, but Batman saved his life. After saving him a second time, Joe Chill thanked him, and Batman said, "You're welcome." Then, the comic ended with Bruce Wayne paying a visit to Joe Chill in the hospital. Bruce read the letters, and then he held Chill as the man who killed Thomas and Martha Wayne died, giving him forgiveness and allowing both men to move beyond the event that defined their lives.