Batman Who Laughs

Batman of Earth -22 was not much different from that of any other version of the Caped Crusader. However, everything went sideways when the Joker started a killing spree across the entire Gotham City, as he was dying from the same chemicals that had turned him into what he was. He murdered many of Batman's enemies including the Penguin, Catwoman, Killer Croc and the Ventriloquist. Batman was then drugged by the Joker, which only affected his body but not his mind, so he could witness the chaos his nemesis caused.

The Joker bombed a hospital in front of Bruce, told him that he had killed Jim Gordon by dumping him in a vat of acid and shot dead many parents of young children in front of him before proceeding to inject the children with the Joker Venom. Batman eventually broke free of his restraints and ended up beating and choking him to death in anger, repeatedly asking him to stop. Unbeknownst to him, the Joker had infected him too when he exhaled the Joker Toxin while dying. The children he infected had also acquired the Joker's personality.

Two days after the murder of the Joker, Batman and Superman talked about what had happened. Bruce revealed that Joker went as far as he did because he was dying. Though he felt no guilt, he affirmed that he was not planning to make killing a regular thing. Superman assured him that the S.T.A.R. Labs branch in Metropolis had agreed to take care of all the Jokerized kids.

A day later, Batgirl, Nightwing, Red Hood, and Red Robin were training in the Batcave when they noticed the training robots were fighting harder than usual. Though they succeeded at the exercise, Nightwing voiced what they were all feeling; something was wrong and Bruce brought them there to talk about it. Bruce explained that he had been infected by an advanced nanotoxin that had been contained in Joker's cell to turned the mind of anyone who killed him like that of his. Nightwing presumed he was training them so they could take him down in case he turned but declined, with the Batman Family pleading to let them help him. Batman however stated that he hadn't called them to help him, but to surprise them as he proceeded to shoot his sidekicks dead.

A week after the Joker's death, Bruce had slaughtered the rest of the Justice League by using the stockpiles of various villains' weaponry they had built up over the years. On the Justice League Watchtower, he cornered Superman and stated that he didn't want to hold back anymore. Clark warned him that people will resist him after realizing what he hs become, Bruce responded that he looks forward to it otherwise it won't be fun. He then brought his wife Lois and Jon before him, the latter also suffering from bleeding eyes.

Bruce then mocked him and asked him to lie to his family that it will be okay, which Clark refused. He then unveiled a warped Damian and the rest of the Rabid Robins to Clark, before showing modified Black Kryptonite, stating that he tested it on Supergirl who killed her own foster parents before dying herself. Bruce's transformation into "The Batman Who Laughs" was finished, allowing him to cackle as Clark and Jon tore Lois apart before dying after he tossed the kryptonite towards them.