- "If I can't have you as a brother bonded by love, then we'll just have to be bonded by hatred."
- —Jeremiah Valeska to Bruce Wayne[src]
Jeremiah Valeska is a terrorist psychopath and the more arrogant and obsessive identical twin brother of the anarchistic cult leader, Jerome Valeska. After Jerome's death and being exposed to his altered chemical laughing toxin driving him to insanity, Jeremiah takes over the role of main antagonist for the final arc of Season Four and a major antagonist in Season Five.
As a child, Jeremiah supposedly suffered years of abuse at the hands of his insane brother, who apparently burnt Jeremiah's bed while Jeremiah himself was in it. Jeremiah would in turn manufacture several lies about his brother that would turn Jerome's entire family against him; it remains unclear how much truth there was in either story. In a desperate attempt to defend Jeremiah from his monstrous brother, his uncle took him away from Haly's Circus, in which his mother Lila worked, and proceeded to take him to St. Ignatius. Following this Jeremiah changed his name and started calling himself Xander Wilde. After finishing school, Jeremiah became a brilliant engineer, designing highly advanced generators for Wayne Enterprises. He also built a labyrinth hideout to protect himself from his brother, which took almost six years of construction. In addition to the hideout which he filled with security cameras, rooms of work and more, he met a young woman named Ecco who started to work for him as a proxy and assistant. Jeremiah would later reunite with his brother, who after a rampage to find his twin, found him in his hideout.
Right after witnessing his brother's death, Jeremiah received a gift sent by Jerome, which is revealed to be a "special" gas created just for him. Upon inhaling it, his face became pale white and a wide red grin formed from ear to ear, finally giving Jeremiah the drive to explore that dark side of him that his brother Jerome had seen. Becoming obsessed with both Bruce Wayne (whom he quickly became friends with each other) and re-building Gotham in his own image after destroying it, he eventually formed an alliance with Ra's al Ghul. After mortally injuring Selina Kyle in an attempt to destroy Bruce's attachments and drive him insane, Jeremiah killed the mayor and demolished all of Gotham's bridges, cutting the city off from the rest of the world and paving the way for Bruce to become the "Dark Knight" Ra's had foreseen. With Gotham City reduced to a lawless "no-man's land", Jeremiah managed to escape into the night, remaining on the loose in the abandoned city.
After Selina recovers, she tracks down Jeremiah and stabs him multiple times with the intent to kill him. Jeremiah survives and proceeds with his plan to reenact the Wayne murders, using Jim Gordon and Lee Thompkins as stand ins, hoping their murders would give him and Bruce a permanent connection. His plan is foiled by Selina’s intervention, and Jeremiah is severely disfigured and brain dead after falling into a vat of chemcials - which ultimately leads to him losing his identity. He is currently in a coma whilst in the custody of Bruce Wayne. Despite this, his secondary plan to prevent the reunification with the mainland succeeds, leaving Gotham’s river polluted with toxic chemicals.
Jeremiah's past is full of mysterious contradictions due to different inconsistent stories told by multiple people. For sure is that he was born to Lila Valeska and Paul Cicero along with his twin brother Jerome. When Jeremiah was a kid, he already drew blueprints for mazes, not unnoticed by Jerome.
At least according to Jeremiah, Jerome would abuse and scare Jeremiah when he was little. Jeremiah would later recount that he realized Jerome was dangerous and knew he needed to get away from him so he snuck away one night from Haly's Circus and had his uncle Zachary place him at St. Ignatius. Shortly afterwards, Jeremiah took on the alias of "Xander Wilde". He himself would later explain that he did this since he wanted to make it more difficult for Jerome to track him down.
Jerome on the other hand claimed that Jeremiah only made his mother believe that Jerome tried to kill him and stories about him holding a knife to his brothers throat or trying to light him on fire were made up by Jeremiah. However, Jeremiah would later agree that some of these things didn't happen exactly like that. According to Jerome, Jeremiah was the one who is responsible for his brother's madness by essentially creating him, giving him his 'one bad day'. Jerome stated that Jeremiah got adopted by rich people after Lila hid him away, therefore explaining his changed name.
Certainly is that he would then study at school and become an engineer. Four years after graduating, he started construction on his hideout, an underground maze bunker in a forest on the outskirts of Gotham City. The building took 6 years to complete.
At an unknown point in time, he met a woman named Ecco and hired her as his proxy and assistant.
Reunited With Jerome
Ten years after Jeremiah's graduation and six years after he had finished construction on his secret office, Jerome breaks out of Arkham Asylum and kills their uncle, Zachary at the diner he owns for the location of his brother.
Jeremiah is then confronted by the stunned Captain Jim Gordon and Detective Harvey Bullock. They ask Jeremiah about him and Jerome, he tells them that once Jerome tried to kill him, so he ran away and changed his name to Xander Wilde. They then find out that he‘s holding Jerome captive, so they immediately order Jeremiah to let him go but he refuses to do so. After finding out that the Legion of Horribles is inside the building, and that they hypnotized Ecco, Jeremiah takes Jim and Harvey into the halls of his house, which were built as a maze that he’s the only one he can get out of. The three find Ecco there but, since she was hypnotized by Tetch, she gets into a fight with them, Ecco easily wins and takes Jeremiah to Jerome, but she’s eventually knocked out by Jim. Jeremiah then tries to escape but Jerome finds him. They have a verbal fight, in which Jerome tells he’s disappointed by what Jeremiah told about him, since, in his point of view, all of the things he said were lies. Jeremiah did agree that certain things that he told were in fact exaggerations of the truth. Jerome also tells Jeremiah that he’s going to drive him crazy and then kill him. Jim and Harvey eventually get to them, so Jerome runs away leaving Jeremiah behind. Jeremiah is later taken to the GCPD so that he can be put into protective custody. 
Jerome took the Mayor, his wife, and the police commissioner hostage. He demanded that Jim bring him, Jeremiah and Bruce Wayne. Jeremiah is hesitant to go at first but later agrees. Jerome straps Jeremiah and Bruce into a chair. Jerome tells the crowd the story of him and Jeremiah and then cuts Jeremiah free. Determined to prove Jeremiah is just like him, Jerome hands Jeremiah the knife and tells him to take his best shot. Jeremiah tries to stab Jerome, who knocks him out with a single punch. Later, Jeremiah approaches Jerome’s body after he fell to his death. As Jeremiah walks away, Bruce asks him to let Wayne Enterprises fund his work. Jeremiah thanks Bruce and shakes his hand.
Birth of a madman
- "..My days were numbered, but you can continue on for me, be my ultimate revenge!"
- —Jerome Valeska announcing his legacy in a recording for Jeremiah[src]
Revealing his dark side
Jeremiah created a recording tape of himself disguised as his deceased brother Jerome and stated that he would have a wake at the GCPD. He then set Ecco to invite Jerome fanatics that were celebrating at his grave.
When Bruce Wayne visited Jeremiah Valeska, he showed Bruce Wayne the prototype of the device he was working on. He also pulled out Jerome's diary which Arkham gave to him after his death. There he revealed that the book was disturbing and holding him back but Bruce morally supported him by saying to quit the book. Shortly after, Bruce received a phone call about Jerome's wake and Jeremiah became paranoid. Jeremiah confessed that he was sprayed the Insanity Gas as Jerome's last sick game and Bruce convinced Jeremiah to visit Jerome's grave to truly convince the cowering Jeremiah that he was truly dead. After visiting the grave and finding it empty, Jeremiah runs away inside the cemetery building and when Bruce catches up to him, it appears as Jeremiah is losing his mind, now that he views that Bruce is his dead brother.
After Jeremiah chases Bruce towards Jerome's Graveyard, Jerome's body is now placed next to the tombstone. Still not buying the fact that his brother is dead, he pulled out a knife from Jerome's corpse and fought Bruce Wayne. Jim Gordon investigates he bunker and a recording starts playing. when Ecco arrived and placed a gun at his head, the recording starts and it looked like Jerome had an extra tape regarding Jim Gordon. After an extensive fight with Ecco, it is revealed to Gordon that Jeremiah was faking the Jerome act as he peels off the fake damaged skin and rubs the makeup off with a cloth.
Meanwhile, after a thug proclaims proudly "Jerome's victorious" Jeremiah murders him in cold blood due to him believing that he was the victorious one and not his brother since he was dead. Now cold and monotone, Jeremiah wiped the blood of his victim off his face, along with the makeup disguising his altered features; he apologizes for the act, saying it was to show Jerome's followers what an utter dud his brother was.
Kicking Jerome's corpse into the grave, he then revealed his plans for Gotham as he pulls out the diary and states he is going to outdo his brother’s goals in a sane matter. Bruce disregards his plan, saying it's complete madness and to carry out Jerome's plans in a "sane" manner. Jerome replies with an entry from Jerome's diary: "Jerome wanted to slather you in honey and have you eaten alive by corpse beetles - me, if I wanted to kill you I'd just do it." However, Jeremiah then said he didn't wish to kill Bruce, as he truly does see him as his best friend. He then reveals to Bruce and Gordon that the generators he invested his money in can double as highly powerful bombs. Back at Jeremiah's residence the bunker's generator starts to overload, but luckily Jim finds a secret buzzer underneath the table and unlocks the door and escapes the bunker before it explodes. Jeremiah and Bruce both presume Jim has died, and Bruce angrily vows that he will stop Jeremiah. Jeremiah knocks him out and drops him into the grave with Jerome's corpse.
Jeremiah and Ecco then head to Wayne Enterprise and kill two guards to obtain their keycards. they open the locked door with the key cards and it is revealed that there is a room full of the powerful generators Jeremiah created and Bruce invested in. He then orders Ecco to move them as he plans to destroy Gotham and "Rebuild it." 
Plan To Rebuild Gotham
- "I'm going to create a new Gotham in my image, but every artist needs a blank canvas so all of this has to go"
- —Jeremiah Valeska to Harvey Bullock[src]
Jeremiah gives Bullock six hours to evacuate the city and destroys the Gotham Clock Tower to show he is telling the truth. Shortly afterwards, his men are shown knocking out and capturing Alfred Pennyworth at Wayne Manor.
Later, when Bruce meets with Bullock, Jeremiah calls him and tells him the address Alfred is at and warns Bruce not to tell the police as Jeremiah knows where Bruce is. Allying with Scarecrow, Jeremiah later watches Bruce via CCTV as he is sprayed with Scarecrow's fear toxin and forced to witness Alfred being tortured in an attempt to drive him mad. Jeremiah remarks that he "envies" Bruce, and that he wants him to be able to embrace his true, darker nature after being forced to lose everything and everyone he loves.
As Jeremiah enters his safehouse, he finds The Penguin, Barbara Kean, Tabitha Galavan, and Butch Gilzean waiting for him with one of Jeremiah's henchmen, Jongleur, hostage; they have also located and taken the cord relay that allows him to detonate all his bombs at once. They demand an additional hour to evacuate the city and $50 million. Jeremiah, knowing they will double-cross him anyway, pretends to agree to their demands and calls the mayor, but then claims he was put on hold, pulls out a bazooka and blows up Jongleur and the cord relay. Furious at Penguin's assertion that he is "out of his mind", Jeremiah remarks that he has always had a backup plan and can simply detonate the bombs in sequence instead. He then tells them he has changed his mind about the deadline due to their interference, and will detonate the bombs as soon as he's a safe distance away. Jeremiah orders his followers to "kill these idiots" and escapes during the subsequent firefight. Arriving at another bunker where the Cult of Jerome are gathered, Jeremiah prepares to detonate the bombs, but it's suddenly revealed that Gordon is still alive, much to his fury. Jeremiah triggers the detonator for the first generator, but it doesn't explode as Bullock found and disabled it just in time. The Cult of Jerome gets angry at Jeremiah, calling him a liar and a fake; he reacts by sealing them inside the bunker and incinerating them, saying he anticipated their betrayal. All but one of Jeremiah's generator bombs are retrieved by the GCPD, while Bruce is able to rescue Alfred and overcome Scarecrow's fear gas with the help of Selina Kyle.
Later, hiding out alone at an abandoned theater, Jeremiah wonders aloud how he was defeated; he concludes Gordon must have found his maze blueprints and sabotaged the sequence by finding and disarming the first bomb (which is almost correct, except for Harvey Bullock being the one who disarmed the bomb). As Jeremiah decides he must start over, he is interrupted by the appearance of Ra's al Ghul, who compliments him on his tenacity and suggests they can cause the destruction of Gotham together. Jeremiah sarcastically replies that "recent events have convinced me of the benefits of working alone" and tries to shoot Ra's, who easily evades his bullets. Realizing that his attempts to kill the Master of the League of Shadows are futile, Jeremiah reluctantly hears him out. Ra's explains that Jeremiah's plan for a "new Gotham" can still come to be with the help of the League of Shadows, and both their plans are not just about Gotham, but about Bruce Wayne, which draws Jeremiah's interest.
Later at Wayne Manor, Bruce and Selina are talking about Jeremiah's obsession with Bruce. Bruce explains that Jeremiah was working on the premise that "one bad day" can drive someone insane. He wonders if the trauma of his own parents' deaths "made him a little insane", and if Jeremiah had sensed that and was trying to bring it to the surface. As Selina replies that Bruce proved him wrong, Jeremiah suddenly enters the room and holds a pistol to her abdomen, remarking that the day's not over yet. He shoots Selina in the stomach, knocking her backwards, then smiles and throws his gun away. As Bruce desperately tries to keep Selina alive, Alfred rushes in, knocks Jeremiah down and begins pummeling him repeatedly in the face. 
Aligned with Ra's al Ghul
- "I didn't yet understand the vision I was servicing, but I do now, my eyes are open, as will yours be."
- —Jeremiah Valeska to Jim Gordon[src]
After being arrested, Jeremiah is held at the GCPD. Talking with Gordon, Jeremiah mockingly says he wishes to press assault charges against Alfred for punching him in the face, to which Gordon (with equal sarcasm) replies that he thinks Jeremiah looks just fine, ordering Harvey to prepare to transport him to Arkham. Jeremiah offers to give up the location of "other" bombs he claims to have planted around the city, in exchange for being allowed to speak alone with Bruce. A few moments later one of his generator bombs (planted by Ra's al Ghul) goes off and destroys City Hall, killing the mayor and seemingly confirming that Jeremiah is not bluffing. Gordon attempts to beat the locations of the other bombs out of Jeremiah, who barely reacts, merely grinning and humming "Ode to Joy". A major finally has Bruce Wayne meet with the restrained Jeremiah, attempting to get the location of the other bombs. Jeremiah reiterates that he believes Bruce is his kindred spirit, and taunts him about Selina's injuries. When pressed about the location of the "other bombs", Jeremiah reveals that the only other bomb was the one he used on City Hall.
Jeremiah finally reveals to Bruce he is working with Ra's al Ghul. The lights suddenly go out, during which several guards are killed and Bruce and Jeremiah both vanish; they have both been evacuated from the GCPD by the League of Shadows, which also steals all of Jeremiah's confiscated bombs and re-distributes them across Gotham's bridge system. The League then brings Jeremiah and Bruce to an abandoned building overlooking Gotham River, where Ra's is waiting for them. Ra's and Jeremiah tell Bruce they'll create a legacy by destroying Gotham, allowing Bruce to be "reborn" as the Dark Knight of Ra's visions. Jeremiah admits he is skeptical of prophecies and visions, but the idea of he and Bruce rising out of the fall of Gotham together appeals to him.Shortly after, Barbara Kean, wielding Ra's cursed knife, arrives, referring to Jeremiah as a "freak". At first they think Barbara came alone, however, Penguin then started screaming and shooting a machine gun at the League, while the whole alliance of Tabitha Galavan, Alfred Pennyworth and the Sisters of the League appeared behind him and began battling Ra's al Ghul's men. Ra's defends himself against Alfred and Barbara, asking her if she will never learn, but she finishes the sentence for him, telling him she gets that the knife has to be held by Bruce Wayne only. Jeremiah uses Bruce as a shield and shoots a member of the Sisters of the League, but Tabitha's whip ties his hands together and pulls him away from Bruce. Galavan then laces her whip around Jeremiah's throat, trapping him in stranglehold and forcing him to his knees in front of her. She tells him "this is for Selina", but before she can deliver a killing blow, Valeska manages to draw Tabitha's own knife and stab her in the leg. Valeska then grabs Galavan, throws her on the ground and grabs her throat with one hand, holding her knife near her eye with the other, smiling sadistically while telling her that it must be very disappointing for her to die like this in case she wanted to avenge Selina. However, Valeska is suddenly shot in his shoulder by the Penguin. Surprised that Cobblepot, of all people, saved her life, Tabitha looks at him in confusion; she doesn't not know yet that he has his own reasons for keeping her alive. After knocking out Palden, Bruce turns to fight Ra's, but both he, Barbara and Alfred are kept at bay by the Master of the League of Shadows. While Ra's is fighting Alfred, Barbara forces the knife into Bruce's hands before ramming it into Ra's stomach. Jeremiah, still lying on the ground with an injured shoulder, watched this with surprise. As Ra's body began to disintegrate, he looked at Barbara Kean, saying "Well done, Barbara".
Right then, the sound of an explosion shakes the whole city, drawing the attention of Barbara, Bruce and Ra's, as well as the horrified Oswald Cobblepot and Jeremiah Valeska, the latter one smiling savagely as one of Gotham's main bridges collapses into the Gotham River. Multiple other bridges follow the same fate, crashing into the water after their connections to the mainland give in to the detonation of Jeremiah's generator bombs. Shocked by this sight, Penguin, Barbara, Tabitha, Bruce and Alfred witness power failures affecting the fallen city. The dying Ra's grabs Bruce's shoulders, looking into his eyes and telling him that the choice is now his: he can either stay Bruce Wayne or accept his destiny and become Gotham's dark knight. With that, Ra's al Ghul's body disintegrates, leaving only the knife behind. Horrified, Bruce turns to face the destruction of his city. By this point, Jeremiah Valeska has already taken advantage of the confusion and escaped. The alliance against him had failed to prevent the city's downfall.
Shortly afterwards, Bruce is seen interrogating a small-time criminal about Jeremiah's whereabouts; he tells him to let Jeremiah know he is coming for him.
No Man’s Land
Jeremiah remained hidden, but at some point had Ecco prove the extent of her loyalty to him by shooting herself in the side of the head. He had the Soothsayers digging underground while he sent Ecco out to gather new recruits to join them by establishing the Church of Jeremiah Valeska.
No Man’s Land: Day 96
Sykes approaches Jeremiah, telling him that he is working his men too hard and they won’t break though for at least another two days. Jeremiah responds by slashing Sykes’s throat, and says they won’t get anyway with that attitude. Jeremiah addresses the Soothsayers as their new leader and says to dig a little deeper because that’s the only way they are making it out. Jeremiah is busy laughing and arguing with himself about a gift that someone’s going to love when Ecco returns with the new recruits. Jeremiah clears his throat and composes himself. He askes Ecco if those are all the new recruits, and she said she thought he would want quality over quantity since not everyone can pass a high caliber test of faith.At first, Jeremiah grabbed Ecco around the throat, seemingly out of anger, but then pulled her close to examine her scar. He agrees that she has set a very high bar for devotion, and then pulls her into a dance. As they dance, Ecco tells him about Bruce and Selina, and that Selina can walk and is out to kill him. Ecco says if she sees Selina she will tell him and then adds that she will kill her. Jerermiah smiles at Ecco, and sends her away with one last twirl before turning away as Ecco walks away with the recruits.
Jeremiah is fanning himself with his hat while “encouraging” the Soothsayers to continue digging. He compares their efforts to a river due to persistence and has them chant that they will dig a little deeper to each of his questions of persistence. Ecco returns and abruptly stabs Jeremiah, who looks shocked into she removes her mask to reveal Selina’s face. Selina asks Jeremiah if this is deep enough for him. Jeremiah rasps that he must say, but Selina stabs him again and tells him not to say anything. She then stabs him seven more times and raises the knife before Bruce stops her. Jeremiah falls to the ground and the Soothsayers attack Selina. Alfred intervenes and throws a smoke grenade while Jeremiah lies on the ground with his eyes open, apparently dead. In reality, he had faked his death because he knew that Bruce and Selina were on his trail, not yet ready to unveil his plans.
No Man’s Land: Day 97
Jeremiah is resting on a make shift bed while his followers continue digging. As soon as they break through, Ecco runs to wake up Jeremiah. She shakes him and Jeremiah says ouch. Ecco notes that the stitches were still sore and that this wouldn’t have happened if he wore that armor she prepared. Jeremiah says that the bullet was making her sentimental and orders Ecco to give her head a shake. Ecco shakes her head and Jeremiah asks if she was better. Ecco nods yes, and helps Jeremiah as he gets up. Jeremiah reminds Ecco that he had told her that he had to let Selina thrust the knife into him at least once to make it look real which trumps precaution for him. Ecco says she understands he had to let Bruce and Selina think he was dead.
Jeremiah suddenly grabs Ecco and tells her he takes it that she has news. Ecco says all systems are go, and Jeremiah impatiently tells her to lead the way. He grabs a lantern and stumbles after Ecco, who leads him into what looks like Wayne Manor where two people sit wrapped in bandages. Jeremiah tells the doctor that he is hearing good things, and the doctor says the bandages are ready to come off, and says his assistant thought he would like to see the results for himself. Jeremiah says he would, and waits as the doctor unveils the bandages. Jeremiah laughs and says they look beautiful. He walks closer to them, and says he loves family reunions.
Later, when Alfred is the street at night, Jeremiah surprises him and knocks him unconscious. Alfred wakes up in Wayne Manor to see Jeremiah. After Alfred threatens Jeremiah if he touches Bruce, Jeremiah answers “Today is the big day.” 
- "They've been doing scans and he has no brain activity. He's no longer a threat. To either of us."
- —Bruce Wayne to Selina Kyle[src]
Jeremiah had Alfred hypnotized by Jervis Tetch, along with two kidnapped civilians that he had surgically altered to resemble Bruce's parents. He stashed bombs all over Wayne Manor in order to have leverage over Bruce. Once his trap was set, Bruce was led to the manor and sees Jeremiah in the corner of the study. Jeremiah explains his plan to have Bruce experience his parents death all over again just so he can be a part of it. He studies over every detail of how the event went in the kitchen with Bruce. Then leaving so he can set up the rest of it. Leaving Bruce and Alfred to deal with the bomb.
Bruce is then led by Jeremiah to the theater where Thomas and Martha had shown him The Mark of Zorro. Showing him his own recreation of the past theatric production starring himself. He taunts Bruce about how he left the theater because he was afraid during one scene in the film. However he then gets "Thomas and Martha" to leave the theater using Tetch's commands, causing Bruce to follow them.
While Bruce is still looking for them, Jeremiah finds out about Gordon and Lee infiltrating Ace Chemicals and that Tetch hypnotized them. He uses them as stand ins for Bruce's parents in the alley and shoots the lookalikes. Then preparing his plot in the alley where the real Thomas and Martha died.
Bruce arrives at the alley, and Jeremiah tells him to step back. Holding a gun ready to shoot Jim and Lee. He explains how he seeks to be bonded to Bruce more than just some random mugger who shot his parents. Then revealing that he now has Lee and Jim instead of his parents. Jeremiah also prepares Ecco with enough chemicals preparing to launch that the mainland will never help Gotham. The murder is interrupted by Selina pouncing from the fire escape. Leading to Jeremiah starting his plan early and ordering Ecco to activate the chemicals. Leaving that for Gordon to handle while he baits Bruce to Ace Chemicals. They have a face off where Jeremiah gets extremely desperate in trying to prove his point. Even knocking Bruce into a railing, but Bruce ducks out of the way, causing Jeremiah to break the railing and fall into the chemicals below.
Jeremiah is later recovered, but is found comatose, severely disfigured as a result of the chemicals.
Though he appeared to be more stable than his brother, calling him after his transformation a “Short-sighted psychopath" who "just wanted to destroy things”, Jerome claimed that Jeremiah was as crazy as he was. He was shown to be deceptive, as he claimed that Jerome had always been trying to kill him, though he later admitted to Jerome that it didn't happen exactly as he had described it. He tried to deceive Jim Gordon and Harvey Bullock that Jerome could not find him, even though he had already captured Jerome. He was overconfident, bordering on arrogance, on being able to keep his brother trapped, something that led to Jeremiah escaping and confronting him. Jeremiah was also willing to let people die if it meant he could avoid Jerome, showing that he was obsessed with his own self-preservation. Despite this, he refused to leave Ecco behind when Jim and Harvey wanted to evacuate him. He only agreed when they promised to return for her, and he showed great relief when he saw her and realized she was unharmed.
After being exposed to Jerome's altered laughing toxin, Jeremiah initially appeared to have been driven completely insane, laughing uncontrollably as he was transformed by the toxin. However, according to Jeremiah, his brother’s gas did little more than alter him cosmetically. Whether he was fully insane before the gas or if he is simply attempting to downplay his brother's effect on him is still unknown; his prior behavior did hint at some repressed mental instability, which Jerome's gas may have helped bring to the surface. Gordon theorized that, by destroying Gotham in such a way that it would form a "maze", Jeremiah was turning the city into the same environment he had always felt safe in, indicating that Jeremiah's mental instability may have originated from his years of hiding from Jerome, alone and underground.
Jeremiah has still shown himself to be highly skilled at deceiving people before and after his transformation, as he was able to act perfectly as Jerome on video tapes of his "will" and deceive Bruce Wayne into thinking he was having a mental breakdown, only dropping the act to illustrate his new sinister personality. Jeremiah has also shown to be quite calm for the most part, carrying out ruthless actions without the hysterical laughter and manic behavior displayed by Jerome; his mental illness has not affected his brilliant intellect, and he does seem somewhat more in control of his actions. However, he is easily as ruthless and cruel as Jerome if not more so, indicated by his casual destruction of Gotham's clock tower just to prove a point, and his shooting Selina Kyle and torturing of Alfred Pennyworth just to "release" Bruce Wayne from everything he loves. While Jeremiah was always deceptive, this degree of ruthlessness was never shown before his encounter with the gas.
Unlike his highly impulsive brother, Jeremiah continued to plan carefully and methodically after his transformation. Whereas Jerome always felt the need to have an audience to whom he could display his schemes and sociopathic tendencies, Jeremiah did not care in the slightest about having an audience; he was always focused on his endgame and usually had a backup plan, making it much harder to anticipate and defeat him. Also unlike Jerome, Jeremiah had more of a long-term vision, describing himself as a "builder" and "artist" and wanting to create something out of his destruction of Gotham, whereas Jerome only wanted destruction for destruction's sake.
However, despite appearing calmer than Jerome, he does sometimes display the same explosive temper when his plans are interfered with, screaming at his followers to prevent them attacking him, which led to him burning them all to death. He also shows a partial denial about his insanity, as he claims he is not insane several times and becomes enraged when anyone (other than Bruce Wayne) says otherwise. Like Jerome, he is something of a masochist after his transformation, being mostly immune to pain and merely grinning when taking a beating from Alfred and later Jim Gordon.
Jeremiah has also shown two significant obsessions. The first is surpassing his brother in every way, including carrying out his various schemes to destroy Gotham but more efficiently and on a greater scale. Jerome was the one thing Jeremiah always feared the most, and after his exposure to Jerome's gas (which was derived from a variation of Scarecrow's fear toxin) his need to surpass his brother could be his way of overcoming that fear. The second obsession is Bruce Wayne, who Jeremiah views as a kindred spirit and "the brother Jerome never could be" and is the only one to whom he (inadvertently) admits his insanity. Believing that Bruce's parents' deaths had caused similar mental trauma, Jeremiah makes many attempts to bring that darker nature to the surface, just as Jerome had to him. However, unlike Jerome (who was similarly obsessed with Bruce Wayne) Jeremiah makes it clear he has no intention of killing Bruce. After allying with Ra's Al Ghul and learning of his plans to transform Bruce into a "Dark Knight", Jeremiah believes he and Bruce are destined to rise from the ashes of Gotham together.
As of Day 96 into No Man’s Land, Jeremiah’s insanity seems to have gotten worse as he is seen arguing with himself and laughing. However, he was able to compose himself when Ecco arrived. He has developed a violent streak as he grabbed Ecco around the throat, but also also seems to have taken a romantic interest in her as he pulls her into a dance while she updates him. He values Ecco’s loyalty as he appears to look upset when he thinks Ecco is the one who stabs him, and somewhat relaxes when he realizes it is Selina. At the same time, he doesn’t seem to want her to care about him too much as he becomes annoyed when the bullet in her head is making her sentimental, and orders her to shake her head to get rid of those feelings.
Originally, Jeremiah was identical to his brother. In his first appearance he had slightly darker hair due to him being more aged (as Jerome had been dead for a whole year before being reanimated). He wore glasses and dressed usually in a red suit and green collared shirt with a purple tie, and occasionally, a blue overcoat.
After his exposure to the insanity gas, Jeremiah's skin turned extremely pale, even paler than his brother's. In addition, his lips became bright red and his eyes piercing green, though he initially hid these changes with makeup and colored contact lenses. As Jeremiah removes both his glasses and (presumably) his contact lenses after revealing himself to Bruce (since his eyes are shown to change from brown to green in the next shot, and subsequently remain green), it appears the gas may have inadvertently improved his vision to the point that he no longer needs glasses. However, he does briefly wear dark sunglasses when he confronts Harvey Bullock outside the GCPD.
After establishing his villainous identity in season 4, he dyes his hair a very dark green and wears a half-purple-half-black suit and yellow tie, covered with a plaid trench coat and red leather gloves; he later trades the tie with a dark green tie, though he retains the gloves. Occasionally he is also seen wearing a wide-brimmed black hat.
In season 5, Jeremiah wears a black and white coat with a red tie and white hat, he also dyes his hair a lighter shade of turquoise. Later on he wears a glittered purple suit with an orange flower in his front pocket, pinstipped trousers, magenta gloves and a crimson shirt and tie.
After his fall in the acid vat inside the Ace Chemicals during his fight with Bruce, Jeremiah was left extremely burned and scarred, wrapped in bandages, his chin has seemingly grown longer presumably from swelling, he is currently in a coma.
- High-level intellect: Jeremiah is shown to be highly intelligent. Since he was a child, he used to draw mazes, and when he grew up, after having the best grades at school, he built one in his house, which he built underneath the woods. Furthermore, he is extremely manipulative as he was able to keep anyone from discovering his insanity for years, even after it was brought to the forefront by Jerome's gas, and he was able to convince everyone that he was Jerome in the tapes he sent to Jerome's followers and the GCPD. Jeremiah also claims to be "vastly more intelligent" than Jerome was. He is a brilliant engineer, designing advanced generators capable of powering Gotham that could double as powerful explosive devices.
- High pain tolerance/Indomitable will: Jeremiah has shown to have a high tolerance for pain, as he showed no signs of pain when Alfred was punching him in the face repeatedly. He later showed only slight signs of pain when shot by Oswald Cobblepot with a machine gun.
- Master tactician: Using his vast intelligence, Jeremiah also filled his secret hideout with security cameras in order to be ready for his twisted brother's arrival, whilst also utilizing the right tactics in order to trap and escape Jerome.
- Evasion: Jeremiah has shown to be skilled in evading people, as he was able to evade Jerome for years.
- Master engineer: After graduating school, Jeremiah used his construction skills of labyrinths in order to build a secretive hideout for himself in order to defend himself from Jerome, which took him six years of construction.
- Impersonation/Acting: He was able to impersonate his brother Jerome in multiple video recordings, making him a very talented actor, even capable of fooling the whole GCPD and the Cult of Jerome with his disguise.
- Skilled leader: Before his transformation, Jeremiah was shown to be timid and hesitant around other people, probably due to his long period of social isolation. However, after his transformation by the gas, he became much more confident and charismatic, enabling him to quickly take leadership over the Cult of Jerome and make alliances with Ra's al Ghul and Scarecrow. It's revealed that, in Season 5, he formed his own cult known as the Church of Jeremiah Valeska.
- Make-up artist: Jeremiah is shown to be a skilled make-up artist on many occasions. After his skin was bleached white, Jeremiah was able to use make-up to hide his transformation from the public for weeks. He was even capable of taking on the appearance of his brother Jerome by the use of prosthetic make-up for the scars.
- Voice alteration: Jeremiah was able to change his voice to make himself sound like someone else. It was shown that he can convincingly imitate the voice of his brother Jerome, a very difficult task, since Jerome got his striking voice because he got stabbed in the throat before his first death, disfiguring his vocal cords permanently after his resurrection.
- Skilled marksman: Jeremiah has shown proficiency with guns and other firearms. He was able to shoot and kill one of Jerome's followers without looking at the man behind him using his hidden sleeve gun.
- Skilled knife-wielder: Jeremiah is skilled at using a knife. This is seen one he attacked Bruce with a straight razor and when he used Tabatha’s karmbit knife against her and almost killed her with it. He profeciantly wielded a switchblade during his confrontation with Bruce.
- Skilled hand-to-hand combatant: Jeremiah has shown some skill in hand to hand combat. This is seen when he managed to pin Tabitha to the ground after stabbing her with her own karambit knife, though he had also taken her by surprise at the time. He was also able to hold his own in a fight with Bruce Wayne.
- Arrogance: Jeremiah believed that he had captured Jerome and could keep him imprisoned. When Jim and Bullock attempted to put him in protective custody, Jeremiah firmly believed he had defeated Jerome. Only for Jerome to outmaneuver him by leading his allies to Jeremiah's location, hypnotizing his bodyguard, and revealing that he memorized the labyrinths that Jeremiah designed as a child. Jeremiah also arrogantly believed that his bomb had killed Jim Gordon, even though he had no proof that he had perished. After his plan to turn Gotham City to ruins succeeded, his sense of ego and hubris grew and Jeremiah gradually became more unhinged after the Cataclysm. He also puts his own life at risk to make his death seem real to Selina, refusing to wear armour that Ecco had prepared for him.
- Ecco: Jeremiah used to care about Ecco to the point that it override his instinct for self-preservation when he feared she could be harmed by the Legion of Horribles, and refused to leave without her. When he saw her, he ran to her without even suspecting she could be mind controlled, and desperately tried to get through to her to the point where she almost brought him to Jerome. While he no longer seems to care about her that way after being driven insane by the gas, she can still be considered a weakness as he would never suspect her turning on him, so his guard would be dropped around her. This made it easy for Selina, wearing Ecco's mask and robe, to sneak up on him and stab him.
- Mental instability
- Sanity: When he was sane, Jeremiah was very timid and fearful of Jerome. He felt like he had to stay in hiding and could only rely on Ecco. He also didn’t seem capable of murdering someone even as terrible as Jerome as he implies he just wanted to hold him captive.
- Guns/Firearms: He uses different firearms, primarily handguns, which he appears relatively proficient with. He used a small derringer pistol that retracts from his sleeve to kill a Jerome follower.
- Knives: Jeremiah has used different types of knives. He used a spring-assisted knife given to him by Jerome to try to kill him and make him given to his killer instincts. He used a straight razor taken from Jerome's corpse to attack Bruce and later used another one to kill Sykes. He used Tabitha's karambit knife against her and almost killed her with it. He used a switchblade during his confrontation with Bruce Wayne.
- Bombs/Explosives: Valeska used a wide variety of explosive devices, particularly the specialized generators he had designed and built with the help of Wayne Enterprises. He modified them to serve as bombs; just one was easily capable of leveling a skyscraper. Being a brilliant engineer, he designed highly sophisticated and efficient detonation systems for his explosives as well. Jeremiah also used a bazooka/ rocket-propelled grenade to destroy Jongleur during his confrontation with Penguin and the Sirens.
- Jack-in-the-box: Jeremiah kept the jack-in-the-box that sprayed him with Jerome's laughing gas and later used it to traumatize Bruce Wayne while trying to prove to him that one bad day is all it takes to reduce the sanest man alive to lunacy.
- Jeremiah falling into the vat of acid in his showdown with Bruce mirrors the Joker's semi-canonical origin from Detective Comics #168.
- According to John Stephens, both Jeremiah and his brother are heavily involved in the origins and philosophy of the archenemy of Batman known as the Joker and take on certain elements of the character that will lead to his origin somewhere down the road. It is unknown at this point whether or not Jeremiah himself becomes the Joker or a literal third character takes his place, either way, the Joker will never fully make an appearence on the show.
- While Jeremiah Valeska may or may not be the Joker, he is portrayed as more unhinged in Season 5. According to Cameron Monaghan, this is because of Jeremiah's newfound ego and hubris after his plan succeeded in Season 4. This resulted in him becoming more arrogant and flamboyant, with the denizens of Gotham City viewing him as a boogeyman figure.
- Monaghan stated that "J's" final scene in Season 5 is "vile, vicious, nightmare-fuel horror and is everything I love about this character."
- On various occasions, Gotham writer Tze Chun has been known to informally refer to Cameron Monaghan's characters individually as "This Joker" on his Twitter feed. As of January 2019, he has done this with both Jerome and Jeremiah respectively.
- Actress Francesca Root-Dodson was so freaked out by Jeremiah's final transformation that her reaction to seeing Monaghan in the make-up was "What the f*** is that?!". She didn't even recognize him.
- Jeremiah is reffered to as "Mr J" in some promotional material for season 5, which is one of the Joker's most notable aliases, usually reffered to by Harley Quinn.
- Jeremiah bears an uncanny resemblance to the Joker from telltale games, with both having an obsession with Bruce Wayne as opposed to Batman. In addition, both were friends with him prior to becoming villains.
- The Joker made his first appearance in Batman #1 (April 25, 1940). He is credited as having been created by Jerry Robinson, Bob Kane, and Bill Finger.
- Jeremiah Valeska is heavily based on the original Joker from the Golden Age of Comic Books and the Joker from Frank Miller's 1986 Batman: The Dark Knight Returns storyline, where the character was portrayed as more cold and calculating than humorous.
- Like the original Golden Age Joker, Jeremiah Valeska's hair appears in a very dark green tone, almost seeming black in certain light conditions.
- Jeremiah's outfit with the purple hat and coat is an allusion to clothes the Joker wore in the comics on multiple occasions, most famous in Batman: The Killing Joke, as well as the 1989 live-action movie Batman.
- When Jeremiah is undergoing his villainous transformation, he clutches his head in a way that mirrors the famous panel of The Joker going insane in Batman: The Killing Joke.
- Xander's assumed surname could be a reference to the wild and unpredictable nature of the Joker. It could specifically be a reference to an episode of Batman: The Animated Series called "Joker's Wilde".
- His role as an engineer is likely a reference to the Joker’s backstory in The Killing Joke where it is mentioned that he was an engineer at the Ace Chemicals plant before becoming a stand up comedian.
- Jeremiah and Jerome share the same facial features apart from environmental changes.
- Jerome being dead for a whole year without aging makes Jeremiah physically older than him, which would explain Jeremiah's slightly darker hair.
- It is possible that Jeremiah's stories about Jerome being a psychopath as a child, are fictional and purely a ploy to get sympathy from those around him. This is in keeping with the Joker character, who mostly changes details about his own past and sometimes tries to invoke a tragic backstory to gain sympathy (such as when he informed Harley that he had an abusive childhood in order to manipulate her emotionally).
- His fake death is similar to that of his brother Jerome's first death at the hands of Theo Galavan, who was also stabbed.
Behind the scenes
- Even though Jeremiah is Gotham's exploration of the Joker's origins, he will never be called "The Joker" as Cameron Monaghan confirmed on his twitter account due to Warner Bros. wanting to use the name "Joker" for future projects. Cameron also confirmed Jeremiah cannot have bright green hair.
- Despite the fact that Jeremiah possibly isn't the Joker, the promo for Jeremiah's first appearance "A Dark Knight: Mandatory Brunch Meeting" teased the Joker's arrival with the question "Who Is The Joker?" (implying a connection between the Joker and Jeremiah).
- This may have merely been a marketing gimmick to hype up the episode. The arrival of Jerome was similarly teased with "Gotham's next villain... Is no joke!"
- The name Jeremiah is possibly used to invoke the similarity with the prophet Jeremiah from Christian, Jewish and Islamic theology. The prophet frequently prophesied the coming doom of the cities of Judah and Jerusalem due to their sins. Jeremiah Valeska plays a similar role especially after his meeting with Ra's Al Ghul, wherein he predicts Gotham city's eventual fall, although unlike the prophet, Valeska is a direct cause of that coming chaos. Valeska's role before his transformation is also largely reluctant and similarly good-natured as the prophet, wanting to save the residents of the city under threat rather than punish them.
- There is a saint Jerome partly known in Christian theology for examining the lives and words of Biblical prophets and making detailed commentaries about them. In vaguely similar fashion, Jerome Valeska also examines and reflects upon the previous work of his brother Jeremiah as well as providing his own insights on their meaning.
- ↑ https://www.youtube.com/watch?v=iwd13B24cXY
- ↑ Lilien, Steven & Wynbrandt, Bryan (writer) & Vrvilo, Maja (director) (April 5, 2018) "A Dark Knight: Mandatory Brunch Meeting" Gotham. Season 4. Episode 17.
- ↑ Cannon, Danny (writer) & Copus, Nick (director) (April 12, 2018) "A Dark Knight: That's Entertainment" Gotham. Season 4. Episode 18.
- ↑ Huston, Charlie (writer) & Milto, Louis Shaw (director) (May 3, 2018) "A Dark Knight: That Old Corpse" Gotham. Season 4. Episode 20.
- ↑ Chun, Tze (writer) & Bailey, Rob (director) (May 10, 2018) "A Dark Knight: One Bad Day" Gotham. Season 4. Episode 21.
- ↑ Stephens, John & Boston, Seth (writer) & Hope, Nathan (director) (May 17, 2018) "A Dark Knight: No Man's Land" Gotham. Season 4. Episode 22.
- ↑ Fiveash, Chad & Stoteraux, James (writer) & Hope, Nathan (director) (January 24, 2019) "Ruin" Gotham. Season 5. Episode 4.
- ↑ Sosa, Iturri (writer) & Tonderai, Mark (director) (January 31, 2019) "Pena Dura" Gotham. Season 5. Episode 5.
- ↑ Sosa, Iturri (writer) & Tonderai, Mark (director) (January 31, 2019) "Pena Dura" Gotham. Season 5. Episode 5.
- ↑ https://www.gamespot.com/articles/gothams-next-joker-evolution-is-actually-a-nightma/1100-6465237/
- ↑ 
- ↑ https://comicbook.com/dc/2018/11/09/gotham-cameron-monaghan-jeremiah-final-appearance/
- ↑ https://mobile.twitter.com/thetzechun/status/982035211910168576
- ↑ https://mobile.twitter.com/thetzechun/status/1077327315577786370
- ↑ https://mobile.twitter.com/thetzechun/status/1076711476365328384
- ↑ https://comicbook.com/dc/2019/03/06/gotham-jeremiah-joker-evolution-reaction-francesca-root-dodson/
- ↑ https://twitter.com/cameronmonaghan/status/995422386437570560