- "I'm more than a man - i'm an idea, a philosophy - and I will live on in the shadows within Gotham's discontent."
- —Jerome Valeska's last words to Jim Gordon, moments before letting himself fall to his second and final death.
Jerome Valeska was a deranged, criminally insane psychopath and murderer. He was the son of snake-dancer Lila Valeska and blind fortune teller Paul Cicero and twin brother of Jeremiah Valeska. Born and raised in Haly's Circus, Jerome murdered his mother at the age of eighteen, which led to his arrest and incarceration at Arkham Asylum. Following a breakout with other inmates orchestrated by Theo Galavan, he became the leader of The Maniax and wreaked chaos upon the city. This later led to his betrayal and murder at Galavan's hands, although his death brought about an underground movement devoted to him and his way of thinking. Jerome was later resurrected from the dead by a follower, allowing him to once again reign terror upon Gotham City. Jerome grew an obsession with Bruce Wayne and the idea of killing him but was stopped and was re-incarcerated in Arkham once more. After Sofia Falcone defeated Oswald Cobblepot, he got sent to Arkham where he met Oswald. Jerome was shown to have full control of Arkham and could escape at any time, however, he says that he wants to make a show of his escape - further displaying the extent of his 'showman complex'. However, he would soon escape with his new allies and fellow inmates Jervis Tetch and Jonathan Crane. This alliance later evolved into the Legion of Horribles, reinforced with Oswald Cobblepot, Mr. Freeze, Firefly and Solomon Grundy, which operated with the goal to drive Gotham City into madness according to a plan by Jerome, while he promised the other members to rule the city after its downfall. On Jerome's request, Scarecrow therefore developed the dangerous Laughing Toxin that Valeska wanted to spread across the city with a blimp. Shortly after, it came to an ultimate showdown between Gordon and Jerome on the top of a building, in which Valeska got shot, only for him to fall, leading to his life hanging in the balance, as he was able to hold on to a pipe sticking off the building. Even though Gordon reached out and tried to save Jerome, the young villain stated that his legacy will live on in Gotham City before letting himself fall to his second and final death instead of having his life saved by Gordon, laughing all along the way down.
However, Jerome knew that his terror over Gotham did not end with his death, which made it easier for him to accept his fate and die with the confidence that his plans will succeed in the end. Though the danger outgoing the blimp filled with laughing gas was averted by the Penguin, Jerome's ultimate revenge was actually more inconspicuous in form of a jack-in-the-box filled with a special laughing gas that he had his allies deposit in Jeremiah Valeska's secret bunker. When Jerome's brother unsuspectingly opened it, he got sprayed by the laughing gas, whereupon Jeremiah was driven completely insane, turning his skin white, his mouth red and giving him green hair.
Jerome was first introduced as a minor antagonist during Season 1, appearing as the main antagonist of The Blind Fortune Teller. He returned in the first few episodes of the Season 2 Rise of the Villains arc as a major antagonist, before his tragic death. During the second part of the Mad City arc of Season 3, Jerome returns once again and takes over the role of main antagonist from Jervis Tetch. During the second third of Season 4, Jerome remained in Arkham and acted as the Bigger Bad, before escaping and becoming the final main antagonist of the season (after Professor Pyg and Sofia Falcone) during the final third.
Jerome and his twin brother, Jeremiah Valeska were born to Lila Valeska and Paul Cicero. Jerome was told by his mother that his father was a sea captain named Sven Karlsen, who died while at sea. When the circus traveled to Kansas City at the time of his 9th birthday, his mother along with a man both boozed, boned, & beat him up. He was crying outside the trailer when Cicero told him that the world didn't care about him and that it was better to realize it then.
According to Jeremiah, when Jerome was a child he would consistently scare and abuse his brother to the point that their uncle, Zachary with their mother’s knowledge would secretly take Jeremiah away from Jerome to St Ignatius for his own safety from the abuse. Although Jerome claims Jeremiah lied about the abuse he suffered to poison the people Jerome loved against him.
Meeting the Waynes
Two months before the death of Martha and Thomas Wayne, the entire Wayne family was enjoying a night out at a circus. As they were watching a performance by the local siamese singers, Jerome knocked into Thomas Wayne. Jerome then snapped at Thomas to which he was chided by Martha for his apparent carelessness. Jerome then insulted them, which prompted another chiding from Martha. After Alfred's reply seemingly garnered nothing but a creepy smile from Jerome, Bruce then reminded Jerome that the act of being rude wasn't funny. Jerome then challenged this remark by referring to Bruce by name and questioning the degree of privilege that was afforded to him. His mother Lila then made an appearance, pulling Jerome into a trailer marked with a sign that said: Snake Charmer. Alfred then criticized the mother's behavior while Bruce remarked how Jerome seemed to be creepy.
Killing his mother
Sick of his mother's constant nagging, especially after she had sexual relations in the room next to his, Jerome killed his mother, and was allowed by Paul Cicero to clean up in his trailer. Jerome was then told by Cicero to scratch the initials for the Hellfire Club on the hatchet used to kill Lila, and to throw it off Arkham Bridge. Later, when Detective Gordon along with Leslie Thompkins and the circus ringmaster, came looking for Lila Valeska, Jerome answered the door to the trailer, denying knowing where she was. Gordon later had Lila's snake lead the group to her dead body, with Jerome faking despair at seeing his deceased mother. At the Gotham City Police Department headquarters, Jerome was questioned by Detective Gordon on whether or not his mother had any enemies, and how he felt about her sex life, in an attempt to discern a possible suspect. Jerome was later brought back to the GCPD on the request of Gordon, who had come to the conclusion that Jerome had killed his mother, and Cicero, who Gordon had also come to the conclusion was Jerome's father, had helped him cover it up. Vehemently denying doing such a thing, Jerome later admitted to it, laughing maniacally after Paul Cicero admitted to being Jerome's father. Jerome was later sent to Arkham Asylum for his crime.
Leading The Maniax
- "Hey Greenwood, what's the secret to good comedy? Timing. And what's courage? Grace under pressure. And... who's the boss? I'm the boss."
- —Jerome during Russian Roulette with Greenwood
Jerome and several others looked on as Barbara Kean walked into Arkham for the first time. He later approached her on the behalf of Richard Sionis, attempting to persuade her that a girl needed a friend in the Asylum, as bad things happened there all of the time. Though she seduced Aaron Helzinger into being her friend, Jerome brought up the point that her new friend was a "gorilla", and that his friend, Sionis, ran the place, and could get her anything she needed. Jerome was later among the six inmates knocked out by the knockout gas that came out of Zaardon's body and abducted by Tabitha Galavan. Regaining consciousness alongside the other inmates, Jerome was formally introduced to Theo Galavan and his sister, Tabitha, with Theo offering the six inmates the chance to become a team of brilliant outlaws that would make Gotham City tremble.
Jerome and the escaped prisoners threw people off a roof onto a crowded street as a way of spreading fear. The next morning, Jerome showed Theo how much of a stage present he had. While examining Theo's weaponry, Jerome got into an argument with Robert Greenwood over who would be the leader. Theo decided to settle it with a game of Russian Roulette. Greenwood pulled first, and then Jerome risked his life by pulling the trigger three times, showing just how crazy he was. After that, Theo and Greenwood both accepted Jerome's leadership. The Maniax's targeted a bunch of high school cheerleaders on a bus. They doused in gasoline and planned to set it on fire, but the intervention of the GCPD forced the Maniax to retreat. Disguised as police officers, The Maniax infiltrated the GCPD. Jerome took Commissioner Sarah Essen hostage. Essen then told Jerome that he will be dead and no-one will remember his name. Jerome hissed that they will spread like a virus and asked her if she knows why. Greenwood said there is nothing more contagious than comedy, so Jerome shot him for stealing his line. Sarah headbutted Jerome, and he said it was his turn. Jerome killed Sarah and left a message for the people of Gotham before fleeing the scene.
The Last Laugh
- "You're all prisoners. What you call sanity, is just a prison in your minds that stops you from seeing that you're just little tiny cogs in a giant absurd machine. Wake up! Why be a cog? Be free like us. Just remember, smile! Oh - time to go. But don't worry, we'll be back very soon. Hang on to your hats folks, 'cause you ain't seen nothing yet!"
- —Jerome's message to Gotham
Jerome's next target was his father. With Tabitha's help, he tied Paul to a chair and told him of how his mother's lovers abused him and that Paul had comforted him, marginally. He asked Paul what his future is, and Paul proclaimed that his son would be a plague among Gotham, and his legacy would leave death and destruction. Jerome killed Paul and made his escape. He and Barbara later teamed up to hold an entire room of people hostage. He dressed as a magician and Barbara was his assistant. They lured the crowd into a false sense of security and then Jerome killed the deputy mayor. Theo put on a show of trying to stop them, and Barbara pretended to hit him with a mallet. Jerome asked for Bruce Wayne, threatening to shoot his butler and guardian Alfred Pennyworth. Bruce revealed himself and Jerome held him hostage. Theo appeared behind Jerome and stabbed him in the neck. Theo apologized to Jerome and said that now he is the hero. Jerome said that Theo said he was going to be a star, but died before he could finish, with a bloody smile on his face.
- "You will be a curse upon Gotham. Children will wake from sleep screaming at the thought of you. Your legacy will be death and madness."
- —Paul Cicero to Jerome
Several copycats across Gotham City began mimicking Jerome's laughter after seeing him on the news seemingly experiencing psychotic breaks, two men even murdered a homeless man, apparently under his influence. Then one of the pair began stabbing his friend to death, thus showing Cicero's prophecy that Jerome's legacy would be death and madness is becoming a reality. Oswald Cobblepot revealed to his gang that even though Jerome is dead, people are still scared of him.
A nightclub and band run by Jeri appears dedicated to Jerome and the Maniax with attendees wearing straight jackets similar to those which Jerome and the Maniax wore when they attempted to set fire to the school bus.
- "I was just reborn. Last year was nothing but darkness... as far as the eye can see."
- —Jerome Valeska to Lee Thompkins[src]
After his death, Jerome Valeska's body was carried away from the stage by GCPD officers and afterwards transported to the police department's autopsy room. Due to unknown reasons, his corpse somehow found it's way to the laboratories of Indian Hill under Arkham Asylum, where he was stored in a tank to be experimented later on by Hugo Strange. Shortly after he was killed by James Gordon and Oswald Cobblepot, Theo Galavan's body was also taken from the morgue to Indian Hill for experiments and brought into the same room where Valeska's corpse was already preserved in his aqua pod along with other deceased criminals like Fish Mooney. After Hugo Strange talked to the shortly before he revived Victor Fries at the Indian Hill facility some time later, he went to a window that allowed him to observe his scientists examining the bodies of Theo Galavan, Jerome Valeska and several others who were floating in their aqua tanks.
After the downfall of Indian Hill, the cryogenically frozen corpse of Jerome Valeska was taken inside a storage warehouse along with multiple other bodies involved with the facility. Dwight Pollard, who used to be an employee at Indian Hill prior to it closing down managed to learn to resurrect the dead based on the research of his former boss Hugo Strange. Dwight was also the leader of Jerome Valeska's cult. After Pollard and his follower Gus decided the time has come to resurrect Jerome and afterwards led the cult of Jerome to the warehouse in order to recover Valeska's corpse. While trying to revive Jerome, Dwight realized that the process hadn't worked and that Jerome was seemingly still dead. With the GCPD closing in quickly, he decided to "give the cult members Jerome" and cut off his face, after killing the associate that helped him, and then escaped. Jim Gordon later saw Jeromes face-less corpse laying on the operating table.
Jerome's corpse was brought to the GCPD morgue where he suddenly woke up and killed a nearby police officer, taking his gun, and also bandaged his face. Later when Leslie Thompkins enters the morgue and Jerome comes up behind her, takes her hostage, and asks her a few questions, such as who killed Theo Galavan, whether her and Jim were still together, and if they had ever done anything with each other. Jerome then asked her where his face was and, with her not knowing the location, decided to gag her. Suddenly, Channel 9 News started broadcasting and showed Dwight with Jerome's face and Jerome proclaimed that Dwight had no charisma. Jerome then took a cop car and, after hitting a pedestrian, went to the Channel 9 News Studio. After Dwight was arrested, Jerome took his face and kidnapped Dwight, leaving in a cop car. Jerome then took him to the cities power plant. There Jerome stapled his face back on with a staple gun and, at first, was nice to a increasingly frightened Dwight, exclaiming "What's a cut-off face between friends". However, he later beat him, tied him up, laced him with explosives, and then began to broadcast a message of his own. He held a speech saying that everyone in Gotham could "Do what you want. Kill who you want". He then lit a firecracker and threw it on the ground in front of Dwight, telling him "I don't forgive you for the face" before laughing hysterically and leaving. Dwight stared blankly as the power plant exploded, killing him and putting Gotham in a city wide blackout.
Obsession with Bruce
Jerome's speech seemed to have a pretty strong effect as rioting began shortly after, with regular citizens taking his "cue". He then went to Bruce's house and began to destroy Bruce's belongings, including the Court of Owls glass statue. When Bruce asked why he was at his mansion, Jerome told him "Because I'm going to kill you" stating that it was the last thing Jerome wanted to do. Bruce then convinced him that his death should be a public one, and Jerome then took Bruce away and told his goons to kill Alfred, however he was saved by Jim Gordon.
Jerome took Bruce to the Boardwalk Circus that his cult had taken over, and Bruce was horrified at what he saw. Jerome's cult had turned the circus's games into much darker versions of them, most of which involved hurting and/or killing people. He then told Bruce that Gotham had no heroes. He was about to throw a baseball at a button that would drop a man into a tank filled with piranhas, however Bruce pushed him. He then pushed the button, dropping the man into the tank and he was devoured by the Piranhas, much to the distress of Bruce. He then used a staple gun to staple his face back on because it was falling off. Bruce asked him if it hurt and Jerome came over and stapled his arm. To Jeromes surprise, Bruce didn't show any emotion at all so he stapled him again and Bruce once again showed no emotion. However, after Jerome stapled his arm for the third time, he yelled out and Jerome laughed. He then took Bruce over to a mirror where a cult member painted his face. Jerome then stabbed the cult member in the stomach, put his finger in his wound and then painted a frown on Bruce's face, saying "Let's turn that frown, upside down" with a laugh. Jerome then took Bruce over to the main part of the circus where a huge crowd of his cult members was waiting for "the main event". He tied Bruce up on a wooden pole with handcuffs and "entertained" his "guests".
He brings a cannon over and sets it up so it would hit Bruce. Then, Jerome proceeds to dump knives, nails and a canon ball into the cannon and prepares to light the fuse. Suddenly, Jim, Harvey Bullock, and Alfred arrives with the rest of the GCPD and begins to arrest/kill the cult members. However, Jerome lights the fuse and ran away laughing. Bruce was able to escape, just as the cannon went off, using the staples to pick the handcuffs lock. Jerome went looking for Bruce and saw him run into a hall of mirrors and followed him. Jerome cautiously steps into the hall of mirrors and later used all of his bullets up trying to kill Bruce, who kept avoiding Jerome. Bruce then said that he wanted Jerome to follow him and that Jerome was going to pay for what he'd done. Jerome then threw his gun down, saying that Bruce can try to be a hero and that they could fight one on one. Suddenly, he pulled out a knife. Bruce tackled him from behind and Jerome dropped the knife as he made a quip saying "What hero tackles someone from behind?". Jerome then told Bruce to "put 'em up" and began to bounce around, not taking the fight very seriously. Bruce brutally beat him down to the ground and jumped on top of him. He continued to punch Jerome in the face until his face literally started to come off. Jerome then told Bruce to "let it out" as Bruce continued to brutally punch him again and again as Jerome laughed. Suddenly, Bruce grabbed a shard of glass and held it up to stab him. Jerome told him to do it in order to prove that Gotham did indeed have no heroes. However, Bruce looked in the mirror and saw himself becoming like Jerome and decided to spare him. He screamed in Jerome's face and throw the shard to the side and left, leaving Jerome to lay there.
However, Jerome wasn't done, and later ran at Bruce and Alfred as they hugged, holding a shard of glass. He was defeated by Jim Gordon, who literally punched his face off. It was later revealed by Harvey that he would be going back to Arkham after the doctors put his face back on. Jim jokingly asked Harvey if he would have liked it better if he had killed him and Harvey replied "No, he probably just would have come back to life again".
Locked Up In Arkham
After he had been blamed by Sofia Falcone for the murder of her father Carmine, Oswald Cobblepot was incarcerated at Arkham Asylum. While heavily ranting about Sofia, Jim Gordon and Victor Zsasz who betrayed him and caused his imprisonment, a voice from the adjacent cell greeted Penguin with the words "Hey, buddy". Even though Cobblepot ordered the other man not to talk to him, the fellow inmate moved on by explaining that this place is full of lunatics and he just thought they could help each other out. Realizing the voice came from the other side of a small grating near the ground, Cobblepot kneeled down to watch through the barred window that connected the two cells. After ironically asking the other prisoner how he could help him, the inmate claimed to be very resourceful before laughing amused afterwards. However, Penguin was immediately shocked since he recognized that insane laugh. Thereupon, the other inmate finally revealed himself through the grating and turned out to be Jerome Valeska himself. After offering Oswald to become his best friend, Jerome moreover asked Oswald to give him a smile before bursting out into maniacal laughter.
Forming The Legion Of Horribles
Jerome later collaborated with Jonathan Crane and Jervis Tetch where they escaped from Arkham Asylum and released the other inmates as a diversion. While Jervis Tetch kept the police busy, Jerome went to confront his uncle Zachary Trumble where he needed some information out of him. Zachary prepared three soups where one will be for Jerome, one will be for Zachary, and the other one turned out to be for Lunkhead who showed up to help Zachary after he spilled some soup on Jerome. When Bruce showed up, Lunkhead attacked Bruce while Jerome started to use bleach to force-feed into Zachary. Zachary got out of it by writing down the address that he was looking for. Jerome thanked his uncle and killed him. Just then, Selina Kyle showed up wanting to do away with Jerome only for her to be thwarted by Bruce. Jerome then escapes while Bruce finds the written address to St. Ignatius which he calls Gordon about. After Jervis was caught, Jerome and Scarecrow free him by fear gassing the police transport and driving it to St. Ignatius.
Shortly after, Jerome tracked down more of Gotham City's most dangerous villains in order to recruit them for his terrorist organization, assembling Victor Fries and Bridgit Pike as well as fellow escaped Arkham inmates Jervis Tetch, Scarecrow and Oswald Cobblepot in one great Legion of Horribles. Jerome then took the whole Legion to the Falcone Mansion, much to Penguin's dislike. Valeska had his followers from the asylum serve food and drinks to the guests, as he himself officially welcomed all of them to their first ever mandatory brunch meeting. He then gave an answer to the question everyone waited for, the reason for the gathering of this Legion of Horribles, as he calls the group. Noticing that this name has a nice ring to it, he orders one of his servants to write it down. Jerome begins explaining that he came up with a plan to turn the city into a madhouse back when he was in Arkham and that he is now at the cusp of making that happen, however he still needs help from all of them.
Thereupon, Mr. Freeze raised his arm, but Valeska commanded him to put all questions on ice until the end, before Jerome turned to Oswald, thanking him for doing his part in hosting them today. Cobblepot then responded that he would do anything for an old friend in a sarcastic tone, leading to Jerome asking Crane for the progress concerning Scarecrow's secret work. Next, Valeska calls Freeze an "ice man" and gives him the task of finding a big laboratory, since Victor is a man of science. He now turned back to the whole group and explained that all they need is Tetch to return with some very important information, but then started shouting at Carl, one of the servants from Arkham, ordering him to use the tongs to lay down the food. However, Firefly next accused him of still being silent about how he plans to take over the underworld, but Jerome stated that this is not his goal, instead he sees himself as an artist who just wants to paint the town crazy. Once that happens he could care less how the other members of the Legion of Horribles rip the city apart. Even though Bridgit seemed very euphoric for this proposal, Valeska explained that it is too early and nothing can happen until they have their one last essential ingredient, the one thing that will tie it all together. Right then, Jervis Tetch entered the Falcone Mansion and came into the dining room, leading to Jerome asking Jervis to sit down and join their conversation by pointing at the empty chair next to him.
being placed in a labyrinth by Jeremiah and Ecco, Jerome finds his way towards the exit and thus his brother. Jeremiah asks Jerome how did he find his way through the maze to which Jerome tells him that even though they don't look the same, they think the same and that Jeremiah drew mazes all the time when he was a kid. Jerome then accuses Jeremiah of fabricating everything Jeremiah accused Jerome of doing to him when they were kids. Jerome finally tells Jeremiah that he is gonna kill him however he will first drive Jeremiah insane.
Tetch and Crane soon come running with Gordon and Bullock behind them. Jerome soon escapes as well. Back at their hideout, Jerome kills a man and Crane and Tetch bring a business man as a test subject for Jerome's plan. Penguin has also brought Solomon Grundy who he states will make a great edition to the team. Jerome then has Crane spray a gas at the business man. The coughing from the man soon turns into manic laughter and Jerome exclaims they're gonna need a lot more the gas while the man's mouth begins to expand and blood begins coming from his eyes as his laughter turns into a final scream.
After creating more gas, Jerome and the legion abduct Holden Pritchard and his friends and Crane gas sprays a woman causing her maniacally laugh while Jerome tells the others to stop taking things so seriously. Jerome asks them what do they have to lose and states, "Except your sanity" before bursting into laughter. Having Crane, Tetch, and Penguin steal a blimp and hypotize the pilot, Jerome and Bridgit Pike take over a concert and bring out the hostages. Gordon, Bullock, Lucius Fox, Bruce, and Jeremiah arrive, having been tipped off by Penguin and Bruce and Jeremiah go towards the stage.
GCPD snipers attempt to take out Jerome however Jerome's henchmen take them out. Tying up Bruce and Jeremiah, Jerome attempts to show the crowd that Jeremiah is just as crazy as Jerome. Jerome frees Jeremiah and gives him a knife and tells him to give "his best shot". Jeremiah attempts to stab Jerome however Jerome knocks him down with a single punch. Gordon has the area evacuated and he shoots Jerome in the shoulder.
Bruce frees himself and knocks out Pike while Gordon goes after Jerome onto a rooftop. Jerome attempts to tell the pilot he's in position however Gordon shoots him twice and Jerome falls off the building. Dangling by his fingertips from a flagpole, Jerome stretches out a hand and dares Gordon to prove himself the good guy and save him. After a brief hesitation, Gordon reaches out his own hand to help. Jerome quickly pulls his hand back and congratulates Gordon on staying to his values and playing by the rules, but points out that because of this his legacy will outlive Gordon, because he does not play by the rules. He grants Gordon one final mocking goodbye before letting go and falling to his death, laughing to the bitter end.
- "Hello, brother. Didn't think you could get rid of me so easily, did you? See, my days were numbered, but you oh, you can continue on for me, be my ultimate revenge! So, calm yourself. Don't fight it. Breathe it in. This gas was a special mixture I had made, just for you. Something to finally set you free. It's time to have some fun. Burn it down, brother. Burn it all down!"
- —Jerome Valeska announcing his legacy in a recording for Jeremiah[src]
After Jerome's death, Jeremiah discovered a gift in his secret office and opened it. The gift is revealed to be a jack-in-the-box in the form of a disfigured clown head that sprays Jeremiah with a special mixture of the laughing venom created by Jerome. The gas then eventually drives Jeremiah completetly insane as Jerome's voice speaks to him in a recording coming out of the gift box, encouraging Jeremiah to be Jerome's sucessor and his ultimate revenge. Even though Jeremiah tried to fight the venom, it ultimately turned him into a complete maniac with white skin and red lips.
- "You will be a curse upon Gotham. Children will wake from sleep screaming at the thought of you. Your legacy will be death and madness."
- —Paul Cicero[src]
Jerome is an utterly remorseless, unpredictable, ruthless, manipulative and psychopathic person who deeply enjoys needless acts of violence and chaos. While he initially acted as a regular person, crying over his mothers death and being polite to others, he showed his true colours once Jim Gordon deduced he had killed his mother. Unlike most criminals, Jerome does not care about organized crime or profiting from his crimes, he simply wishes to cause as much chaos and violence as possible. He was shown to be a new class of criminal, one who killed who he wanted, and did what he wanted with no overall motive other than making Gotham crazier than it was.
Jerome is a showman; whereas most criminals would work from the shadows and conceal their crimes, he often broadcasted the carnage and violence he would inflict through his crimes, and he would always have a theatricality to his insanity. Jerome desired to create a legacy for himself, no matter how cruel or corrupt, and he shows sadistic pleasure at the prospect of being remembered as a curse upon Gotham. His cruelty and remorseless nature was also shown by the fact that he killed most of his family members, never once hesitating when he had the chance to. It should be noted that Jerome’s family members had abused him throughout his childhood which resulted in a lack of emotional family bonds. This lack of familial attachment and negative experiences are likely the reason he didn't hesitate to kill them, or show remorse after ending their lives.
Despite his ruthless and psychopathic nature, Jerome is capable of making allies and alliances. This is best shown through his leadership of the Maniax before his death, leading a cult that worshipped him after he was resurrected, taking over Arkham Asylum, and leading the Legions of Horribles. However, his only loyalty is to himself, as he would frequently kill his allies or followers if he felt they had outlived their usefulness, let him down, or if he was simply in a bad mood. He did show true respect to Theo Galavan, seeing him as a mentor due to his belief in him, though this respect was later shattered after Galavan killed him, and he was brought back to life, wishing to kill him. Though he initially seemed to have a positive relationship with his father, shown by the fact the man willingly helped him to hide his mothers body, Jerome showed the same disregard for others towards him, eventually killing him and framing him as part of Jerome and the Maniax's escape from Arkham.
Jerome was also shown to have a disregard for his own safety, shown when he pulled the trigger on himself three times during a game of russian roulette, and allowing himself to fall to his death instead of letting Jim Gordon save him. He was also highly sadistic and even masochistic, as he enjoyed inflicting pain and had no problem receiving it himself.
After he was brought back to life, Jerome was shown to be even more ruthless, cruel and psychotic. He wished to bring all of Gotham citizens down to his level, describing how 'we could all go insane with just one bad day'. However, Jerome also showed a reflective side to himself during this time, as he admitted that no one ever helped him, though he was quick to taunt Bruce for helping him and letting him almost get killed by the man he had saved him from. He would also claim to Jeremiah that their mother gave up on him once he was hidden away, and that she had been 'poisoned by your stories.' This indicates that, while he would always have been ruthless and insane, Jerome may have had a chance at being normal if his family life had been different, though he did not seem to pay much attention to these musings, and instead embraced his insanity.
In his last days, Jerome showed some twisted affection towards his brother: although he threatened to kill him, and did assault him during their last confrontation, he tried to encourage Jeremiah to embrace his hidden insanity as Jerome had, and to no longer hide it. He also showed that he had no problem with dying a second time, as he willingly fell to his own death, laughing as he did so.
- High-level intellect: Jerome is exceptionally intelligent, especially when it comes to inducing chaos.
- Explosives expertise: Jerome managed to create a bomb powerful enough to destroy the Gotham power plant.
- Leadership skills: Jerome was able to assume leadership of the Maniax, a group of insane and volatile individuals, and later led hundreds of chaotic citizens of Gotham into causing chaos and havoc. Following his second incarceration in Arkham, he was able to become leader of both of the inmates and the guards, claiming to be very charismatic.
- Master of deception: Prior to him revealing himself as a psychopath, everyone saw him as a harmless, innocent young man.
- Eidetic memory: Jerome was able to remember the mazes his brother drew when they were kids, despite having been away from him for years, allowing him to travel through Xander's house-maze with ease.
- High pain tolerance/Indomitable will: Having been abused as a child, Jerome has learned to withstand physical pain. Even when Bruce kept punching him in his stapled face, he smiled and stayed conscious. He also seems to have little to no fear of death, or anything else besides boredom.
- Hand-to-hand combat: Jerome is a skilled combatant, though far less skilled than Bruce Wayne or other trained combatants.
- Skilled knife-thrower: Jerome is skilled at throwing knives, such as when he threw a knife into the Deputy Mayor's chest.
- Skilled marksman: Jerome is skilled at using firearms.
- Guns/Firearms: Jerome carried a variety of firearms with him like handguns, revolvers, and shotguns.
- Knives: Jerome carried various knives such as trench knives, throwing knives, and pocket knives.
- Laughing Gas:
- According to executive producer John Stephens, Jerome is the predecessor to the Joker in Gotham's universe and could be replaced by others who watch the actions of him, his brother Jeremiah and a possible third or even fourth one, adopting them as inspirations.
- Jerome's resurrection was foreshadowed during the second half of season 2, as a body double was seen in Indian Hill in a couple of scenes (being that in "Rise of the Villains: Worse Than A Crime" and "Wrath of the Villains: A Dead Man Feels No Cold") although his face wasn't seen. In the finale for the season "Wrath of the Villains: Transference", a shadowy figure resembling Jerome and sharing a similar laugh is seen exiting the prison bus along with the other monsters from Indian Hill. This appeared to imply Jerome had been resurrected, although season 3 appeared to change this as he was still dead.
- In a post on Cameron Monaghan's Twitter account in which he made reference to the fact anyone in the show could be the Joker (in reply to fans who were not happy that Jeremiah Valeska was possibly not the Joker), he acknowledged the Jerome lookalike from the end of season 2 and referred to him as a "hinted clone" and that he could be destined to become the Joker.
- It is unknown whether or not Jerome was born insane or his unstable nature is the result of his broken home life.
- According to actor Cameron Monaghan, Jerome was supposed to die in "Mad City: The Gentle Art of Making Enemies". "He was going to be beheaded and that was going to be it for him. Ultimately they decided that instead, we’ll go the opposite way and really embrace the idea of the character being involved in the Joker mythos."
- According to Executive producer Bryan Wynbrandt in regards to Season 4, "Professor Pyg is set to be the big villain of the first part of the season, and Jerome is going to be taking over the back half." This makes Jerome the seventh 'big villain' of the series, behind Fish Mooney (Season 1), Theo Galavan (Rise of the Villains), Hugo Strange (Wrath of the Villains), Jervis Tetch (Mad City), The Court of Owls (Heroes Rise), and Lazlo Valentin (first half of Season 4 - A Dark Knight).
- Jerome has committed matricide, patricide and avunculicide.
- Jerome Valeska acts as a tribute and precursor to The Joker, with his existence delving into the mythology of the character. The Joker was created by writer Bill Finger and artists Jerry Robinson and Bob Kane, first appearing in Batman #1 (April 1940). The character would then become the most dangerous and well-known adversary of the Batman, being prominently featured in many major storylines concerning the Dark Knight as well as appearing multiple times in adaptations spanning movies, television shows and video games. During the third season, Jerome's appearance is based off that of the New 52 Joker, whose face ends up being removed and later reattached, although the Dollmaker does the removing whereas Dwight Pollard is responsible for taking Jerome's face. Jerome's story arc also takes inspiration from a few Joker scenarios, with the Carnival theme being based off that of the acclaimed comic book Batman: The Killing Joke and Jerome's confrontation with Bruce Wayne in the glass house paying homage to The Dark Knight Returns. In the Season 4 episode A Dark Knight: A Beautiful Darkness, Jerome dropped a Joker card in front of Oswald as a nod to The Joker. In the later episode A Dark Knight: Mandatory Brunch Meeting several more nods were given to The Joker. These include Jerome's white suit which somewhat resembles what the Joker wore in The Dark Knight Returns, his line which goes "Y'all could go insane with just one bad day." which refers back to a famous monologue by Joker in Batman: The Killing Joke, as well as the use of laughing gas which is eponymous with almost every version of the Joker known.
- Jerome Valeska is not The Joker himself. In 2015, Bruno Heller went into detail, "As the show rolls on, people will see how a mythology is born, how a kind of cultural mien is created that will lead us to the Joker himself... There's a tradition in forebears and ancestors of those characters that went into creating them. So, to me, Jerome is genuinely the mother and father of the Joker. He is the seed of the Joker... We have not cast an actual Joker yet. I think people would have felt that we had sold them a dummy [when Jerome was killed]. That it was a red herring. When in fact, it's actually a much deeper and longer game we're playing. The audience will see an organic progression towards the real history of the Joker, rather than a kind of legendary supervillain who creates himself out of nothing." In 2017, executive producer Bryan Wynbrandt described Jerome as an "homage" and "the impetus that eventually creates the Joker". He elaborated, "The more that we see him, the more he carves out his own path I'd say... The Joker, in our hearts, he is his own character... I think that's what makes him so exciting is that he's not the Joker. He is Jerome."