Within the canon of their worlds, Spider-Man and Batman both have codes they follow. Their morals are strong, carrying them since the beginning of their heroism. Although, the thought of these great heroes failing and becoming the very people they are against is intriguing. Luckily, the comics world is full of worlds, and universes that have different versions of these characters.
More specifically, looking at these worlds where Batman fails, and ultimately snaps. Or maybe a world where Spider-Man's mind was inhabited by his worst enemy. Regardless the options are endless, but these two evil versions take the cake for having One Bad Day.
The culmination of all the Dark Knights worst fears, from Earth-22 of the Dark Multiverse. Was born after a killing spree caused by the Joker across Gotham City. The Joker, murdering all the caped crusader’s closest allies, bringing them all down with him as he is dying.
Batman trying to halt the spree, gets drugged by the Joker himself paralyzing him forcing him to watch all the chaos ensue around him. If it could not get any worse, Joker forces Batman to watch as he bombs a hospital and shoots parents in front of their children to recreate the traumatic event that created Batman.
Once regaining movement and mobility, Batman then breaks his most sacred no kill rule. Grabbing Joker by the neck, he snaps it, ending the chaos and horrors of the madman. Unfortunately, as Joker dies, he exhales a toxin infecting the only one who is in the vicinity. Batman.
With the infection spreading, so does Batman's grasp of reality and the morals that have been grounding him ever since becoming the Dark Knight. What follows is destruction, killing all the bat family and the Justice League. Breaking all his rules and becoming a horrific hybrid of his own set of skills, and the maniacal mind of his worst enemy... The Joker.
Just when Peter Parker is doing well for himself, his Parker luck runs out and gets his mind swapped with one of his rogues’ gallery. While visiting a dying Dr. Otto Octavius he swaps his mind with Peter so that instead of himself dying it is Spider-Man.
Donning a new title, the Superior Spider-Man Otto takes the mantle of the web-slinger. Unfortunately, his methods were opposite of Spider-Man and way more violent in punishing criminals.
While the time within Peter’s body was only a year, the damage to his reputation was done. In the end Otto realizes the difficulty with being a hero and understands the role Spider-Man plays in the city. So, in an act of selflessness, he swaps back, allowing Peter to take back control of his own body in order to stop the Green Goblin.
