Jerome Valeska was born on Gotham, the brother of Jack "Napier" Valeska. As a child, Jerome has a father that always abused him. Due to his mother's life style as a greedy woman and the way she treated him by always giving him orders, Jerome hated her (and his father) and wanted to see her suffer. Jerome finally killed her when he was 12. He was eventually caught by Marvus Gordon, James Gordon's father, but then was released. His life with his abusive father finally end when Jerome murder him when he was a teenager, but people think this is some criminal did, and Jerome was not caught again.
After his father and mother dead, Jerome became a war soldier when he was young. He had fight with French, and was later became a hero of Gotham. But this is not what Jerome want.
Apprentice of Darth Plagueis
Jerome was found by Darth Plagueis when he was fighting with the French. He took Jerome as a apprentice, with Darth Sidious, who became Jerome's friend for Sidious have sad life to tell Jerome. Plagueis teach Jerome to more evil, insane, fun, and show no good to people. This was not known by Gotham's people or anyone.
The soldier of the Republic
Jerome became a soldier from the planet Coruscant whose people were engaged in a bitter thousand-year war of attrition with their enemies. The conflict left him horribly scarred and crippled, and he always has scars on his face. After know this wars mean nothing, Jerome retired and finally got every things he need to know from Darth Plagueis to became a terrorist. He wore a clown like makeup, and took the name the Joker. Sidious gave Jerome money to do his works.
The first days of the Joker
The Joker has a nephew, Melvin Reipan. He gave Reipan works to do, and Reipan also did them good.
First attack on Gotham
When Joker was 49, he plan to attack Gotham. He lead group of bank robbers, (Grumpy, Happy, Dopey,Chuckles, Bozo and an unidentified bus-driver) under the direction of the Joker,robbed Gotham National Bank which was used as a money-laundering front for Gotham's gangs. The clown mask wearing robbers whittled down their own numbers within minutes in a series of calculated betrayals. Finally only "Bozo" remained, who revealed himself as the Joker to the manager of Gotham National Bank, who had earlier confronted the robbers with a shotgun. In addition, largely because he couldn't resist appearing on-camera, he also deliberately unmasked himself in front of a surveillance camera and posed. The Joker then escaped with the bank's cash in a yellow school bus, concealing his identity by driving within a convoy of other buses, and also leaving the manager at the mercy of a gas grenade stuck in his mouth.
Shortly following the bank robbery, Italian crime boss Sal Maroni mentioned the Joker's recent theft of Mob owned cash to his fellow crime leaders at a business meeting, dismissing him as a threat and saying that he was a "nobody" wearing a "cheap purple suit and make-up." The Joker, overhearing this comment and the plan presented to the Mob by Chinese mobster, Lau, arrived unannounced at the meeting while faking a laugh, as he saw their "so called plan" as a bad joke. The mobsters were at first unwilling to hear him out, and Gambol, one of the crime lords who seemed to take the most dislike for the Joker, sent one of his men to take him out by force.
The Joker unexpectedly performed a magic trick by making a pencil "disappear," and embedded the pencil in the table, and shoved Gambol's man head-first into the pencil where it indeed disappeared inside the man's head, instantly killing him. The Joker also mentioned that his suit wasn't cheap and that they ought to know this since they bought it, which meant that he used the money he stole to buy his suit. He proposed that it was Batman's interference that had resulted in idealistic leaders like Harvey Dent rising in popularity, and offered his services to kill him for half of all the money that Lau, an illegitimate Chinese accountant, took away from Gotham for safe keeping. He also warned them that Lau would betray them if arrested, claiming to know a squealer when he saw one. While the Bratva mobster, the Chechen, and Maroni were interested, Gambol, angered by the Joker's lack of respect, attempted to attack him, forcing the Joker to reveal his insurance policy: several grenades hidden under his coat, allowing him to make a quick escape.
Frustrated, Gambol proceeded to put a bounty on him. The Joker later took revenge that night by having his men come to Gambol, claiming to have killed the Joker. In a bit of unintended tragic irony regarding the fate of his actor, the Joker's 'dead' body is brought inside in a garbage bag before attacking Gambol and proceeding to tell him the origin of his mouth scars as a way of psychological torture and intimidation, then when Gambol is most terrified and shaken, the Joker proceeds to kill him with the knife. Then with the remains of Gambol's men overpowered and at his mercy, he takes a pool stick and breaks it in half, making it spear-like and says that there is only one spot open at the moment to join his "team", then throws the piece of sharp stick at the middle of Gambol's scared men and has his gang, made up mostly of mentally-ill and unstable vicious crooks escaped from Arkham Asylum who seem to have taken the Joker as their leader, to make Gambol's men fight to the death with the stick until only one is left, and advising them to "make it fast".
Later, the Joker and his gang stormed a fundraiser at Bruce Wayne's penthouse to kill Harvey Dent. When he was unable to get the guests to inform him of Dent's location, he decided to settle for killing off the guests. He then attempted to threaten an unintimidated guest whom he noted bore a resemblance to his own hated father, to which Rachel Dawes intervenes. The Joker then tells her another chilling story, about where he got his Glasgow smile. This time, the Joker had a wife who thinks he does not smile much. Then his wife got given a Glasgow smile, and to show that he still loves her and does not care about her Glasgow smile, he self-inflicted his Glasgow smile onto himself, to which his wife was disgusted by, and left him. The Joker finishes the story by saying he saw the funny side to the story; he is now always smiling. Dawes knees him in the crotch, but he laughs it off and says that he likes people with a little fight in them. Suddenly, Batman appears, and fights with the Joker. The Joker only managed to escape by throwing Rachel Dawes out a window, who Batman then leapt after and saved. This encounter also led him to initially suspect that Batman's true identity was Harvey Dent.
The killings then continued with two innocents and an attempt on the mayor's life at a memorial for the murdered police commissioner. The Joker appeared in public without makeup, impersonating one of the Honor Guards, as well as having most of his gang impersonate the rest of the Honor Guards. In order to further ensure that the GCPD is kept on its toes, he also placed a sniper rifle on the windowsill of the apartment room, as well as a timer to release the blinds for the GCPD sharpshooters to shoot at anyone hapless enough to be caught in the trap. Afterwards, Joker, still disguised as an Honor Guard, shot his rifle at Mayor Anthony Garcia,Lt. James Gordon was struck in the back after willfully leaping in front of Garcia, in order to fake his death to avoid any future attempt by the Joker of attacking him with his family at home. As a result of this, Batman told Dent to call a press conference so he could reveal his identity and stop the killings. In a surprise move, Dent instead claimed to be the Batman himself and was subsequently arrested.
While being transported the Joker and his gang attacked the caravan of police vehicles, attempting to kill Dent with amachine pistol, a shotgun and even a rocket-propelled grenade. He and his men managed to destroy nearly all the vehicles in the convoy, but when he attempted to destroy the armored car carrying Dent, Batman intercepted his RPG, at the cost of destroying the Batmobile (he was able to detach part of it in the form of the Batpod). Realizing that Dent wasn't Batman, the Joker broke off his pursuit and attempted to ram the Batpod instead; Batman managed to dodge him and then capsize the Joke's eighteen-wheeler using his cable launchers.
Batman then bore down on the Joker (who was goading Batman to kill him by screaming "HIT ME!"), but stopped short of ramming the maniac at the last second, forcing him to crash. The Joker prepared to unmask Batman but Lt. Gordon, newly resurrected from his hoaxed death, stepped behind him and held a shotgun to his head, saying "We got you, you son of a bitch." The Joker was successfully jailed at MCU, and as a direct result, Lt. James Gordon was promoted to Commissioner by the Mayor. He also does a sarcastic clap for the newly-promoted Commissioner.
With the Joker in custody, Gordon and Batman believed his madness was over, but became alarmed when informed that Harvey Dent had gone missing. Desperate, Gordon let Batman interrogate the Joker for information, but the Joker seemed unshaken by the pain. Instead, he gleefully told Batman his view of people as selfish and violent, only needing a little pressure before descending into madness. He also admitted he could never kill Batman, considering him his only equal. Dent's kidnapping was part of a test, to see if Batman would save him or Rachel, whom the Joker could tell Batman cared for. The Joker willingly told him where both were located. After most of the police were gone, the Joker took his guard hostage and escaped by detonating a phone-activated bomb he surgically planted in the stomach of one of his menwho was arrested with him, with Lau in tow. After failing to save Rachel Dawes, Gordon had come to the realization that it was a setup and Joker had planned to get caught to obtain Lau.
Dent and Rachel each awoke tied to chairs with barrels of explosive material surrounding them and a speakerphone hooked up to the other's location. Rachel confessed her love for him and agreed to marry him. Dent fell on the floor and his left side was completely immersed in turpentine. Batman arrived but found the D.A. instead of Rachel. He realized that the Joker had lied about Rachel and Dent's whereabouts to further crush Batman's morale. Batman rescued Dent as the building exploded and the District Attorney's face was badly burned, while Gordon was unable to rescue Rachel before the explosion. In the hospital, Dent was driven to madness over the loss of Rachel, and blamed Batman, Gordon and the Joker. This act caused Sal Maroni to tell Gordon the Joker's location, finding him and his craziness "too much" for business.
The Joker later met the Chechen in a container ship with Lau and was given his reward: half the mobs smuggled money, which he then doused with petrol, and set alight with the Chechen's cigar, which Lau on top of the burning money. He then betrayed the Chechen and took control of his men. He declares that Gotham deserves a new breed of criminal - one unmotivated by money or power but who commits crime purely for fun. This corresponds with something Alfred said to Bruce Wayne before - "Some men aren't looking for anything logical, like money. They can't be bought, bullied, reasoned, or negotiated with. Some men just want to watch the world burn".
The Joker then made a call to a news program where Coleman Reese was threatening to go public on the news with information about Batman's identity. He was interrupted by the Joker who stated he had changed his mind, believing Gotham to be too boring without Batman. To "give others the fun" he threatened that if someone didn't kill the employee in sixty minutes he would blow up a hospital. Gordon then abandoned his ambush on the Joker to focus on evacuating all city hospitals.
During the mass evacuation, the Joker disguised himself as a nurse and entered the hospital room of Harvey Dent. He first apologized to Dent, maintaining that he was not responsible for Rachel’s death as he lacks any idea for the repercussions of his actions, while the restrained Dent attempts in vain to kill him. The Joker introduces the former D.A. to his view of the world that his time in Gotham has introduced him to, that people, or "schemers" as he calls them, are the truest form of evil in the world, as it is them who lay out the plans of society, including when human lives are expendable.
To prove his argument, he points out that if his threats were aimed at 'gangbangers' or 'soldiers', then people wouldn't really care as society trains them to see the death of such people as acceptable. Thus, he turns the disillusioned Dent against society and against the "schemers" who put his and Rachel’s life in danger, namely the corrupt cops who kidnapped them, as well as the "schemers" who viewed Rachel's life to be expendable, namely Batman and Gordon.
Giving Dent a gun, the Joker advised him to break away from the law that failed him and turn to chaos, which the Joker describes as the only truly fair system, as the fate of everyone would be only decided by chance, without the interference of the flawed laws of Man. Dent responded by flipping a coin to decide the Joker's fate, giving him the same chance Rachel had. Soon after Dent left, Joker detonated the Gotham General Hospital, skipping merrily away down the street, before pausing, noticing that most of the explosives haven't gone off, before tapping the detonator again, which explodes the remaining explosives. He and his men then steal one of the nearby evacuation buses and kidnapped the TV reporter and his crew inside.
The Joker declared that anyone left in Gotham would be subjected to his rule. He told people they could leave now but that he would have a surprise for them in the tunnel and on the bridge, which people then avoided, using instead two ferries, one ship full of ordinary civilians and one of criminals. However, the Joker had loaded each of them with explosives. In hopes of showing everyone how evil and corrupt they can be, he gave the passengers of each ship the detonator to the bombs to the other and offers both survival if they detonate the other ferry. If they didn't choose by midnight, the Joker would blow up both ships.
Batman discovered not only the Joker's location at an unfinished skyscraper, but that the majority of his "gang" were actually hostages wearing clown-masks with unloaded guns taped to their hands and that the people dressed as hostages were the actual criminals. Batman was forced to fight not only the Joker's men but the SWAT teams as well to save the hostages. He finally confronts the Joker, which led to a final battle between the Joker and Batman (with the Joker using a metal bar and a knife). But Joker manages to get the upper-hand and pins Batman under the scaffolding. He gleefully waited as the ferry's deadline neared, and was visibly disappointed when both groups of passengers refused to kill the other to save themselves. The civilians voted to blow up the other ferry, but could not bring themselves to actually do so, while one of the criminals stepped forward and, taking the detonator, threw it out a window, saying that the cops should have done that from the start. As the deadline passed, Batman asked the Joker if he was trying to prove that everyone was as ugly as him deep down, bluntly informing the Joker that he was alone in his corruption and insanity. Before he could detonate both ferries, Batman hit him with his shooting wrist-blades and threw the man over the edge. The Joker starts to laugh as he falls to die, but Batman, refusing to kill him, instead caught him with his grapple gun and leaving him hanging for the police to capture.
With this act, the Joker acknowledged that Batman really is incorruptible but that Dent is no longer the "White Knight"; he's unleashed the scarred man on the city. Joker states that Dent was his "ace in the hole" in his plan to show the people of Gotham that everyone is corruptible, thus undoing Dent's work before his transformation into Two-Face. Batman then angrily left the Joker to dangle helplessly as he started laughing manically and then was approached by the SWAT team who had him at gunpoint.
Return to Darth Sidious
After the battle, Joker was sent to Arkham. He escaped there again, and return to Darth Sidious. He tell Reipan to do some works.