The joker has a fascination with Batman - his gadgets, his commitment to fight crime, and his uncorruptability.
Since the relationship between Joker and Batman is older than most real-life romantic partnerships, there are likely even more stories that feature the Clown Prince of Crime professing his undying love for the hero he's always trying to murder in horrific ways. The Joker really does love Batman in his own twisted way.
Their relationship is driven forward by the Joker's bizarre fascination with Batman and The Caped Crusader has even stated that, in his own way, the Joker is in love with him. The Joker views himself as Batman's greatest necessity and in most origin stories, Batman was responsible for the creation of the Joker.
The Joker doesn't exactly like anyone, and respecting the abilities of a fellow villain is one of the few versions of positive feelings the Joker can have towards someone. He isn't one for long-standing friendships nor relationships, and his most famous companion's relationship is nothing short of toxic.
Joker believes Batman's public outing will ruin the fun he's having with the Caped Crusader, and this attitude broadly follows the DC comic books.
Though the film is populated with comic book characters, no iteration of Batman has revealed Bruce is related to his ultimate archenemy. (He's famously an only child.) That's only the film's first radical twist to Batman mythos.
Throughout their storied relationship, the Joker has known Batman's true identity and has chosen to ignore it. He simply can't bring himself to care about Bruce Wayne the human.
The Joker Hates Nazis, According to New DC Comics Story.
His signature cackle paired with batshit crazy, chaotic and sinister plans add to his universal appeal. Perhaps more than any other reason, what makes him so admired by fans is the fact that the Joker wasn't inherently bad, to begin with (at least in certain renditions of his backstory).
In the latest issue of Batman, fans learn that even Batman's other villains are afraid of the Joker and his upcoming war against Gotham.
In the different forms of Batman media, Batman and the Joker are depicted as being enemies because they have opposing goals within Gotham City. While Batman is trying to save the city from its own darkness, the Joker enjoys causing further chaos.
Without Batman, the Joker is directionless
J bests his rival at long last — leaving Gotham without a Batman to protect it.
He eliminated the corrupt police, he destroyed organized crime financially, he uplifted Gotham's spirit, and he even got rid of the flying pest that had been corrupting Gotham ever since he declared himself it's protector.
Bruce was in a battle with Scarecrow when he accidentally got injected with a shot of fear toxin. Unknown to everyone, though, Batman had previously been poisoned by (a now-deceased) Joker's venom. The venom caused apparitions of the Joker to appear to Batman, and was slowly warping his mind to become more like Mr. J.
The most common story involves him falling into a tank of chemical waste that bleaches his skin white and turns his hair green and lips bright red; the resulting disfigurement drives him insane. The antithesis of Batman in personality and appearance, the Joker is considered by critics to be his perfect adversary.
Martha reveals that she forced Psycho-Pirate, a villain with extensive knowledge of the entire DC Universe, to tell her the name of the Joker in the main DC Universe. It is then revealed that the Joker's real name is “Jack Oswald White.”
The psychopathology Arthur exhibits is unclear, preventing diagnosis of psychotic disorder or schizophrenia; the unusual combination of symptoms suggests a complex mix of features of certain personality traits, namely psychopathy and narcissism (he meets DSM-5 criteria for narcissistic personality disorder).
The Joker is one of the main antagonists of DC Comics, most often pitted against his archenemy Batman, Superman, and occasionally the Justice League as a whole as a part of the Legion of Doom. In the comics, the Joker is portrayed as a master criminal whose characterization has varied.
The Joker is one of the most iconic and recognized villains in popular media, having been ranked #1 on Wizard's list of the 100 Greatest Villains of All Time. He was also ranked #1 on IGN's ist of the Greatest Comic Book Villains of All Time in 2009.
Following her introduction to the DC Universe in 1999, Harley Quinn was depicted as the sidekick and lover of the Joker as well as the criminal associate and best friend of fellow supervillain Poison Ivy.
Historically, Harley Quinn is a former psychiatrist who falls in love with the criminally insane Clown Prince of Gotham. Joker manipulates Quinn and she falls for his devilish charm, not knowing that it would be her eventual downfall and she would become a partner in clown-themed crime with Joker.
Stronger: Bane
Although he may not have been as intriguing of a villain as the Joker, he was almost certainly stronger and far more connected. Bane has a genius intellect and is beyond physically powerful. There's no way that the Joker would last long if Bane used his full physical and mental force against him.
The Killing Joke explains that the Joker became insane as the result of one bad day. That seeing his skin changed finally caused him to snap.
Bruce Wayne has kept his identity as the man behind Batman secret for decades but a few select villains have figured out who he is. Batman's true identity as Bruce Wayne is one of the worst kept secrets in the DC universe.