It was never fully revealed what the exact cause for the creation of the infection was other than it originating from Joker's mutated blood. It was probable that the chemicals that caused the Titan Disease (and maybe chemicals already in the clown's blood) caused Joker's blood to mutate, creating the infection.
It was sometime afterwards, that those individuals began showing signs of the Joker Infection. Batman linked the infection to Creutzfeldt–Jakob disease] (or CJD) but it was mutated beyond anything on medical record. Like CJD, the Joker Infection attacked the brain.
Nicholson's Joker was a criminal who was physically and mentally altered after falling into a vat of hazardous chemicals. Heath Ledger's iconic take reinvented the character for a new age, permanently imbuing the clown with angst.
The Joker has undergone many revisions since his 1940 debut. The most common interpretation of the character is that of a man who, while disguised as the criminal Red Hood, is pursued by Batman and falls into a vat of chemicals that bleaches his skin, colors his hair green and his lips red, and drives him insane.
The Joker Can Be "Cured" Using Technology from the Marvel Universe. Dr. Briar's experiment ends up being a complete success, and the Joker is rendered entirely harmless by her biotechnical chip. After the procedure, the Joker has absolutely no interest in harming others and is actually pretty cowardly overall.
Joker, wearing his own version of the Batsuit, used Batman's extensive (and expensive) gadgets against him in the climactic fight, but, as soon as he got the upper hand, the villain was surprised by a bullet to the eye from Harley Quinn.
The Joker himself is immune to most if not all strains of Joker Venom (a possible side-effect of his own constant exposure to and abuse of his chemical weaponry).
The comics series The Joker: The Man Who Stopped Laughing features Batman's nemesis get pregnant after a curse is placed on him, Daily Mail reported. Eventually, the Joker "vomits a sort of brown goo" that transforms first into a baby boy and then into a mini version of himself.
The most common backstory for The Joker is that he was a failed comedian who took a job for the mob in order to pay bills that involved stealing from a chemical plant. In a confrontation with Batman, he accidentally slipped into some chemicals which bleached his skin and caused him to go insane.
Ledger, who played the Joker in Christopher Nolan's The Dark Knight, died on 22 January 2008 following a prescription drug overdose in his New York apartment. He was 28 years old. Stephen Gaghan, a director and writer, recently divulged that Ledger had died with the script for his film in bed.
When Jerome seemingly died, his corpse went through a procedure which attempted to revive him. When the procedure seemed to fail, a cult decided to instead remove Jerome's face due to his criminal reputation.
Mad Love introduces Harley Quinn as a former psychologist named Harleen Quinzel who fell in love with the Joker during her internship at Gotham City's Arkham Asylum and details her transformation into the Joker's villainous accomplice Harley Quinn, as well as the Joker's lack of respect for Harley.
Narratively, he got a permanent smile scarred into his face just by being born, which is tragic. But cinematically, the idea came from the 1928 silent movie that inspired the character's creation in the first place, The Man Who Laughs (the link to The Batman Who Laughs is clear).
In the documentary I Am Heath Ledger (via Digital Spy) it's revealed that, in order to keep the prosthetics in their place as they got loose when he spoke, Ledger had to lick his makeup to keep it in place, and it ended up becoming part of the Joker's manic personality, as well as his most memorable mannerism.
In the documentary "I Am Heath Ledger" (via Far Out), it was revealed that the silicone pieces would sometimes come loose, prompting the actor to keep licking his lips to make sure they stayed in place. Eventually, Ledger embraced the licking and made it part of his character's mannerisms.
While Harley Quinn's immunity to the Joker's toxins is a great benefit for herself, Harley being able to cure others of the villain's sinister serum is something that seriously comes in handy.
Much like her son, Penny suffered from an unspecified mental illness. She was responsible for letting her former boyfriend abuse Arthur in his childhood and was temporarily sent to the Arkham State Hospital for unsolicited claims.
History. According to the Joker, his father was "a drinker and a fiend". Joker claimed that his father gave him his cheek scars due to his being terrified when his father brutally stabbed his mother sadistically with a kitchen knife when she attempted to use to defend herself.
Everything seems to be going swimmingly until Arthur lets himself into Sophie's apartment after his mother's death, and she barely recognizes him. Viewers then see alternate versions of Sophie's scenes where Arthur is interacting with thin air, clearly indicating that the entire relationship was a fabrication.
In Injustice: Gods Among Us, Harley Quinn reveals she gave birth to Joker's daughter, but gave her up for adoption rather than subject her to a life with Joker as a father. Similarly, Harley becomes a mother to twin children in the Batman: White Knight universe, though with happier results.
The Joker becomes both verbally and physically abusive. Rather than blame the Joker for this abuse, Harley convinces herself that Batman is to blame because Batman is constantly getting in the way of her being with her “Puddin.” After her failed attempt to kill Batman and some time in Arkham, Harleen returns.
Penny Fleck marks the second time in Batman media where the Joker's mother has appeared, especially given that the Joker's origins are a mystery as well his name in the mainstream comic book continuity.
Not only is the iconic Batman nemesis a genius chemist, but he is also capable of masterminding intricate schemes against his enemies, leaving a history of destruction, death, pain, and suffering unlike many ordinary criminals in the DC Universe.
The make up is so white it makes clean teeth look yellow and nasty. So I firmly believe the way he's drawn is on purpose. They know that his teeth would appear yellow and grimy under all that makeup in real life, so he's drawn that way.
