In LOTUS, after Lucifer took possession of President Jefferson Rooney, he had sex with Jefferson's aide and lover, Kelly, who was unaware of the possession. After their first round, Kelly said she believed Jefferson Rooney (Lucifer) would make a great father, which inspired Lucifer to sleep with her again and conceive a child.
The conception of the Nephilim was felt by Castiel, who was miles away inside the Men of Letters Bunker. He and the Winchester brothers decided they needed to get rid of the child, as it was the "spawn of Lucifer".
After Sam and Dean successfully banished Lucifer thus saving the president, Castiel took Kelly away to a diner. He pleaded with her to get rid of the child, informing her that it was not Jefferson's, but the Devil's. Kelly excused herself to the bathroom and fled the diner. As she rode away in a taxi, she insisted through a phone call that the baby was still hers, and she did not want to get rid of it.
In Family Feud, after his mother was rescued by Dagon from angels trying to kill her and him, Dagon revealed to his mother Kelly that he was a boy. Elsewhere, Lucifer mentioned to Crowley that his son's power is a chip off the old block.
In The British Invasion, when Kelly began experiencing "weird little pains", she ordered Dagon to take her to a doctor, in case something was wrong with the baby. Dr. Turner could not find anything wrong with the baby itself, and Dagon assured Kelly that the child was fine and he was going to become big and strong. The pains were, in fact, the start of intense, life-threatening pain that Kelly was going to experience since birthing a Nephilim was always fatal to the human.
In The Future, Kelly only has less than a month left before she gives birth. Kelly is told by Dagon of the unimaginable horror the child will unleash upon his birth. In an effort to stop this, Kelly commits suicide only to have her child resurrect her. Following her resurrection, Kelly states that she felt his soul surge through her and that it was good, not evil though Dagon believes the child only brought her back to ensure his own survival.
After being kidnapped by Castiel, Kelly insists on the goodness of her child. Castiel is ordered by Joshua to bring Kelly through the portal to Heaven which will kill both Kelly and her child and scatter their atoms across the universe. As Kelly continues to insist on her son's goodness, Castiel asks her if this is true, who will guide and protect the child after his birth since Kelly will die in the process. The child kicks moments later and Castiel feels it. As the Winchesters arrive, the child has a premonition of a conflict between Dagon and Castiel at Heaven's Portal and instructs Kelly to take herself and Castiel there, having chosen Castiel to protect and guide him after sensing Castiel when he touched Kelly's belly.
At Heaven's Portal, Dagon kills Joshua and effortlessly defeats Kelly's defenders. As Castiel and Kelly stand hand-in-hand, Jack empowers Castiel, causing his eyes to glow. With the child aiding him, Castiel is easily able to overpower a shocked Dagon and negates her powers. Telling Dagon to "call it a miracle", Castiel uses Jack's power to incinerate the Prince of Hell.
Following Dagon's death, Castiel tells the Winchesters that it was both himself and Lucifer's child who killed Dagon. Castiel tells the Winchesters, who planned to remove the child's grace and leave him human and powerless, that he now knows that the child must be born with all of his power intact as he now has faith in the child's goodness. As they depart in his truck, Castiel tells Kelly that the child showed him "the future".
In All Along the Watchtower, Castiel takes Kelly to a lakeside house which is set for a newborn baby. Kelly is desperate for her son to be born good and well-loved. During labor, a rift to an alternate reality is opened and Team Free Will uses it to trap Lucifer within but he drew Mary with him as they tried to push him in. Sam returns to the house to find Kelly dead, along with a trail of scorched footprints leading to the nursery. Inside, he discovers a full-grown Nephilim with golden eyes sitting in the corner, and gives Sam a menacing smile.Lost & Found, Sam tries and talk to Jack, who asks if he is his father. Sam tells Jack he is not his father and is still attempting to speak with Jack when Dean arrives and shoots at Jack, narrowly missing him after Sam tried to stop him. Jack becomes angry and in self-defense begins screaming, causing a pulse of energy to emanate from his body that blows out all the windows in the house and freezes Sam and Dean in the air before jettisoning them back into the wall, knocking them unconscious.
Jack leaves the house and wanders the woods until he comes across a Pirate Pete's Jolly Treats, and asks at the drive-thru for his father. Seeing that he is naked and confused, an employee, Clark Barker, calls his mother, Sheriff Christine Barker, to deal with the situation. Sheriff Barker arrives to find Jack still standing in the parking lot. Seeing the sheriff's gun, Jack initially takes a defensive stance until Sheriff Barker assures him she only wants to help him.
At the Sheriff's Department, a now fully clothed Jack begins absorbing his new surroundings while Sheriff Barker tries to get information out of him. Jack is only able to tell her that his mother is in Heaven and that he is looking for his father. Jack is then fingerprinted and sits with Clark who asks what Jack is on. Jack tells him he isn't stoned, but that he is hungry. Clark takes Jack to the break room, where Jack tests out a new power that allows him to get free food from the vending machines; he becomes a big fan of nougat. Soon after showing this ability to Sheriff Barker, Jack begins picking up angel radio, which causes him debilitating pain. When Sheriff Barker tries to stop him from leaving, Jack loses control and sends her flying into the vending machines. As he tries to leave the station, he comes face to face with Dean, but before Jack can do anything Sam hits him with a taser, rendering Jack unconscious.
Sam and Jack are placed in a holding cell, while Dean explains the situation to the sheriff. When Jack comes to, Sam apologizes to Jack and explains he didn't want to hurt him. Jack tells Sam he was scared of the voices he was hearing, which caused him to lose control. Jack tells Sam that he doesn't know if he can open another rift and that he needs to find his father, who will protect him. When Sam tells him Lucifer doesn't do that, Jack corrects him and tells him that Castiel is his father, because his mother told him that Castiel would keep him safe. He also explains that through his mother, he knew the world was dangerous and had to mature into adulthood immediately after his birth to protect himself.
A trio of angels led by Miriam arrive at the station; two of the angels are able to locate Jack in the holding cell area. When they try to take him, a fight ensues, ending with Sam banishing them. The action of the sigil causes Jack momentary discomfort. Miriam enters the holding cell area but is flanked by Sam and Dean. Feigning that she is giving up, she tells Sam that if the angels can't have him, no one will and drives her angel blade into Jack's heart. After Sam kills her in retaliation, Jack drops to his knees and pulls the blade from his chest. To all their astonishment, he is fine.
In the aftermath of the clash, Sam and Dean decide to take Jack with them back to the Men of Letters Bunker, but before going home, the trio goes and give Castiel and Jack's mother Kelly a hunter funeral pyre.
In The Rising Son, Jack spends his time with Sam and Dean Winchester. Jack notices that Dean doesn't particularly like him and tries to emulate him in order to appear more favorable. Jack eats a burger and drinks beer the same way (and the same time) as Dean does, but this only serves to annoy Dean. The trio is soon visited by Donatello Redfield. Donatello notices that Jack isn't human and is amazed by his status as a Nephilim. After hearing Jack is Lucifer's son, Donatello admits that he himself no longer has his soul. Donatello also states Jack's presence is nothing like his father's whose was dark and toxic. Later on, he is told by "Donatello" to use his powers to open a rift, but just as he nearly completes it Dean, Sam, and the real Donatello appear. Jack realizes he was tricked by Asmodeus who attacks his friends causing him to get angry and attempts to attack Asmodeus but the latter flees. During the night, Dean approaches Jack and tells him that while he is unsure of being evil if he turns then he will be the one to kill him.
In Patience, Sam has Jack practice his powers to move a pencil with his mind which he struggles with and becomes irritated that he can't do one good thing right. Very soon, he is able to move the pencil and tells Sam of his feat taking the latter's congrats in stride as he mentions Dean's promise to kill him but Sam says he won't allow it.
At night, he overhears an argument between Dean and Sam where he hears Sam defending him and Dean accusing Sam of using him to bring back their mother. He then hears Dean state he was the cause of Castiel's death which causes his eyes to glow as he says the angel's name. This act unknowingly sends a telepathic message to Castiel in The Empty and he awakens after hearing Jack's voice.
In The Big Empty, Jack is watching videos on the computers before he is invited by Sam to join him and Dean on a mission though he refuses due to Dean's distrust of him while also revealing he is aware Sam wants him to control his powers to save his mother.
Sam confirms he wants to save his mother but states he does care for Jack and promises not to allow Dean to hurt him as they go off to their quest.
The trio goes to the victim's house where they put on their aliases as FBI, which confuses Jack, and ask the neighbor about what she saw and she explains it was definitely her old neighbor's wife. Dean and Sam begin making deductions on what could of it done it as they decide to visit the dead woman's grave. They burn the body to ensure it's not a zombie and tell a curious Jack they did so for his mother and continue to ponder on what did it.
Sam then returns and holds her at gunpoint revealing he discovered Mia is a Shapeshifter as Dean joins him in pointing a gun.
Mia states she did not hurt anyone as the brothers tell her that some of her patients have ended up dead which surprises her. Knowing they are hunters, Mia proclaims her innocence and tells them she has an alibi and to check it out to confirm it.
Dean goes to do so and returns confirming she is telling the truth, to her relief. They then ask if she isn't killing anyone who was as she deduces it to be her old lover Buddy who is also shifter and enjoyed killing just to torment others. However, she is trying to atone for her past by helping people get through their grief. Understanding, the Winchesters state if Buddy is doing so then he must be taking on forms of her patients to get information and kill them.
Dean and Jack go to a possible lead, as Sam stays with Mia before he leaves in Mia's car to pursue him.
Dean and Jack return soon after and while Dean calls Sam, Jack speaks with Mia and tells her that he is not actually Sam and Dean's brother and that his mother actually died when he was born. He shows her the video of his mother and asks Mia if she will take on Kelly's form for him to gain some closure.
Seeing his pain, Mia agrees and shifts into the form of Kelly while Jack has his eyes closed. Mia, as Kelly, then comforts Jack about his self-doubt. Dean suddenly barges in and knocks out Jack before holding Mia at gunpoint. This Dean reveals himself to be Buddy.
Buddy ties up Dean and Jack while speaking to Mia, angry that she abandoned him to start a new life. He proclaims his intention of destroying that life by having her kill the hostages but she refuses and tells him to kill her. While they talk, Dean wakes up Jack and orders Jack to use his powers to free them. Jack, afraid his lack of control over his own powers may hurt Dean, refuses to obey the order.
Just as Buddy is about to shoot them, he sees Sam return and readies to kill him by tricking him into coming to him. When Sam starts to open the door, Mia tries to stop Buddy but is pushed aside. Buddy shoots at Sam, but Jack uses his power to cause the bullet to ricochet into the wall. This saves and allows Sam to shoot Buddy, killing him.
Mia apologizes for the trouble she has caused and promised to do something about Buddy. She laments that all her attempts to help people were for naught but Jack states she helped him in his time of need. This somewhat relieves her spirits as she smiled at him in thanks.
At the bunker, Dean meets Jack and congratulates him on his actions in the mission as Jack accepts it with a smile.
In Tombstone, Jack goes over cases on the computers just as Dean and Sam return to the bunker with Jack questioning how their case went before noticing their strange behavior as they reveal a resurrected Castiel. Jack is surprised as he brings up the brothers' statement of nothing coming back from being burned but soon hears it is partly because of him begging for the angel's return is why he has come back. Excited by this, Jack greets the newly resurrected Angel with a hug and proceeds to tell everyone he found a case. Despite it seeming like Dean is humoring him, it turns out that the grave robbery was a real case just not a zombie like Jack thought but rather a Ghoul. Jack is told of them which he labels as a "zombie shapeshifter". Jack also recognized the ghoul and deduced its identity as the mortician's boyfriend from a picture he had seen there.
After tracking the ghoul to a bank, a gunfight breaks out. In an attempt to stop it, Jack unleashes a telekinetic blast that throws the Ghoul and a security guard back. The security guard hits his head on a pole and dies. Jack seems to be struggling with the fact he has killed someone and is sent back to the bunker. While Sam and Castiel attempt to console him and tell him that he just made a mistake Jack seems to be taking it harder than the others realize. Once Dean returns, he explains he had the ghoul take the fall of the guard's death as Jack has an outburst regarding the dead man and is scared that he will hurt the others saying they are all he has and he can't hurt them. Jack throws them back saying he is sorry and teleports out of the bunker.
In War of the Worlds, the Winchesters and Asmodeus attempt to find Jack who has managed to cloak himself from Asmodeus' detection. After escaping from the alternate reality, a weakened Lucifer tells Castiel that he needs Jack's help to defeat the alternate reality Michael. Lucifer also learns Jack's name from Castiel and seems impressed. At the same time, the Winchesters put out an APB with every hunter they know for Jack and have Sheriff Jody Mills put out a police APB at the same time. After capturing Lucifer and Castiel, Asmodeus also became aware of the invading Michael, stating if it was true he needed Jack on his side.
In The Scorpion and The Frog, the Winchesters continue their search for Jack. They are approached by the King of the Crossroads Barthamus who offers a Nephilim tracking spell to find Jack in exchange for the Winchesters helping him to steal back his bones from Luther Shrike.
Ultimately, the tracking spell is destroyed when Alice burns Barthamus' bones to kill him, resulting in Barthamus being consumed in flames. Though they lost their chance to find Jack, the Winchesters are pleased with the outcome as they stopped Barthamus and saved Alice from her deal.
In The Bad Place, Jack is revealed to have been learning to control his powers and attempting to prove that he is good by locating and rescuing Mary Winchester for Sam and Dean since he knew they missed her. However, while he has been able to feel the alternate realities, he lacked the ability to actually see them and so could not open a rift. Using what the Winchesters taught him, Jack does research and learns about dreamwalkers who have the ability to see into other worlds.
In an attempt to rescue Mary, Jack contacts dreamwalker Derek Swan. Using cash, Jack is able to convince Derek to help him in trying to open a rift into the alternate reality. As Derek uses his powers to search for the correct reality, Jack telepathically connects with Derek's mind to see what Derek sees for himself. Though the two manage to find Mary, Derek is not strong enough to hold the connection long enough for Jack to open a rift. Jack stops before he can seriously hurt Derek and Derek points Jack to Kaia Nieves who is the most powerful dreamwalker Derek has ever met. Derek is also able to give Jack a suggestion on the best place to attempt to open the portal.
Shortly afterwards, angels looking for Jack torture and kill Derek. Derek's murder is discovered by Sheriff Jody Mills who learns that Derek's girlfriend saw Jack shortly before Derek's death. After getting confirmation that Jack was who the girlfriend saw, the Winchesters come to the wrong conclusion that Jack murdered Derek and is now looking for Lucifer as they saw the picture of the apocalypse world.
Jack is able to track Kaia to a drug treatment facility and at first claims to be there for a cocaine addiction. Jack eventually admits that he needs Kaia's help and offers to help Kaia escape in exchange. Subduing a doctor, Jack is able to help Kaia escape through a triple-locked door. However, Kaia refuses to help Jack and runs off while the Winchesters finally catch up to him. Jack is surprised to learn that Derek is dead and explains what he was really up to, telling them he learned to control some of his powers. He then shows them the vision Derek saw of their mother, letting them know their mother is still alive.
Jack joins the Winchesters in searching for Kaia but is shocked to realize that they had believed him to be Derek's killer. When they explain that they believed him to be searching for Lucifer, Jack explains that Lucifer is nothing to him and that the Winchesters and Castiel are his family. Dean agrees with the sentiment and praises Jack's efforts to rescue Mary as Jack accepts it with a smile.
As they search for Kaia, Jack learns from "angel radio" that the angels have kidnapped Kaia. The Winchesters and Jack manage to capture the male angel who, along with a female angel, is attempting to lure Jack in the hope that he can help them create more angels. Jack refuses and when the angels attack, telekinetically blasts the female through a glass window and a brick wall. As the male attempts to kill Dean, Jack forces the male angel with telekinesis to stab himself with his own angel blade, killing the angel.
After the rescue, Kaia continues to refuse to help the Winchesters and Jack due to her fears of The Bad Place. Desperate to save Mary, Dean forces her at gunpoint to join them. As they make their way to the location suggested by Derek, Jack offers to show Kaia what Derek saw so that she can see that it's not all bad. Kaia agrees and Jack telepathically connects with her and shows Kaia Derek's vision, gaining her cooperation.
As they drive, the Winchesters, Kaia, and Jack come under attack by the female angel and six others. The group flees onto a ship where they put up angel warding, but the angels combine powers to begin destroying it. Though Jack has the power to defeat the angels, he realizes that they will use "angel radio" to cause him debilitating pain and capture him. At Kaia's suggestion, she and Jack combine powers in an attempt to open a rift to Mary. Telepathically connecting to Kaia, Jack guides her in moving away from the Bad Place and to Mary. As the angels break through the wards, Jack and Kaia find Mary and Jack begins opening a rift. However, Kaia flashes between Mary and the Bad Place. Finally, with a scream from Kaia, the two emit a yellow glow that opens a rift and sends out a wave of energy that disintegrates the attacking angels.
Due to Kaia flashing between Mary and the Bad Place, the group ends up separated from each other. Kaia ends up on the side of the road while the Winchesters are transported to the Bad Place. Jack arrives alone in the alternate reality and wakes up at the feet of Mary who is trapped in a small metal cage. As Mary stares at Jack in confusion, Jack looks at Mary's predicament with worry.
During Devil's Bargain, the Winchesters are informed by Castiel about Michael and realize Jack, as well as Mary, are in danger. They seek out Donatello to read a tablet to find a spell that would open a rift to the other world to save them before Michael invades. Asmodeus (while disguising himself as Castiel) got some information about Jack's location from Donatello.
In Good Intentions, Jack has been captured by the angels with Zachariah going through Jack's mind by playing a scenario of Sam and Dean being in danger in an attempt to get him to open a rift to the other world. Michael is annoyed with his subordinate's actions but Zachariah is confident he'll succeed in his task. When Zachariah plays another scenario, this is one of Castiel telling Jack humans only destroy true beauty of the world. Jack refuses to believe that and soon realizes the deception of the illusion, he wakes up from the illusion to see the two angels before him. He identifies Michael who flings Jack aside and prepares to make him submit, Jack stands defiant and prepares for a fight.
Michael overpowered and threw a battered Jack in Mary's cell. Jack awoke and spoke to Mary and tells her who he is as she recalls him as the Nephilim Kelly gave birth to. Jack is told by Mary of Michael's intentions to kill her in front of Jack if he refuses to comply with opening a rift to their world so he can invade. Jack refuses and wants to get her to safety but his powers are negated as a result of a headache. Hearing this, Mary reveals to him her head does as well but there is a spot where it doesn't hurt. She deduces Michael did ward it and that Jack can get them out, her theory is correct and they escape.
After escaping the two spot figures approaching them and hide, they are found by the people who question if they are human or a threat. However, one of them reveals himself to be Bobby Singer, a friend of the Winchesters in the main world. He recognizes Mary and decides to help them and they go to his Bobby Singer's colony which is protected from the angels. That night, Jack spends his time doing shadow puppets with the children of the camp.
However, when Bobby notices he has powers and learns Jack is a Nephilim, he orders Mary to get Jack out as he compares him to the angel's past betrayal. Mary agrees and states she will go with him. The next morning, Mary tells Jack they have to leave which he knows is due to him. As they move, angels led by Zachariah arrive to attack the colony. Jack and Mary are found by Bobby who blames Jack's use of his powers for how the angels found them. Bobby decides to evacuate his people as Jack offers help but Bobby angrily rejects Jack's offer and leaves to fight the attacking angels as Mary goes to evacuate the children and tells Jack to hide.
Jack runs through the forest but recalling Sam and Dean's teachings, he turns back and finds Mary who is about to be killed by Zachariah. Jack orders him to back off but Zachariah ignores him and advances as Jack uses his power to lift him and destroys him as the colony watches this feat. However, Bobby spots three more angels flying in, but Jack combusts the angels in mid-air, saving everyone.
In the aftermath, Jack is praised for his actions by Bobby and the colony, as Mary congratulates him which he states is because of what he saw from her sons. He then tells her to truly save this world he has to kill Michael, a decision met with shock from everyone.
In The Thing, the Winchesters finally succeed in opening a rift to Apocalypse World. Dean chooses to go through with Arthur Ketch to rescue Mary and Jack while leaving Sam behind with Gabriel, Jack's uncle.
In the main universe, Gabriel is informed by Sam of his nephew and how he is in the other universe.
After being rescued, Charlie reveals that Mary and Jack now lead a resistance movement against Michael and the angels and last she heard, were fighting in Dayton, Ohio. Out of time before the rift closes, Dean returns to the Main Universe while Arthur remains behind in Apocalypse World to find Mary and Jack and help the resistance coordinate for Dean's inevitable return with reinforcements.
During Beat the Devil, as the Winchesters, Castiel, and Gabriel prepared to open the rift to save Jack and Mary they find Gabriel was too weakened. As a result, they capture Lucifer to keep it open for them long enough to travel through Apocalypse World.
While held captive by Rowena, Lucifer learns of Jack being sent to the other world and breaks free to kill the witch but she repels him and he is sent to the world as well.
After Sam is killed by vampires, Lucifer resurrected him as a way to get on Jack's good side.
Meanwhile, Jack reunites with Dean and Castiel while meeting his uncle Gabriel. He is told of Sam's fate and becomes distraught. Castiel tried to comfort him but Jack turns him away asking both his uncles why they didn't resurrect Sam as Gabriel tells him that they weren't strong enough to resurrect him. Jack is then happy as Sam arrived at the camp alive and well, however, his smile disappeared as Lucifer arrived as well. Lucifer looks at the surprised Jack and greets him.
During Exodus, Jack was shocked to meet his father as the latter approached him. However, Dean stopped this by telling Jack not to approach or talk to him as he ordered Gabriel to kill Lucifer. An argument ensued, as Jack teleports himself away after becoming upset in the process. Jack went to the forest where he thought back on his mother's words and pondered on what to think of Lucifer.
Jack returned to the camp where he decided to hear Lucifer out, despite protests from Castiel but Jack insisted on talking to his real father. Lucifer was pleased to hear this and began to speak to his son. Lucifer told Jack his version of his history and tells him of his family such as Jack's grandfather God who Jack asked about before Dean stopped the talk. Jack stood his ground by stating he wanted to know about his father who was pleased by this. Lucifer continued the talk by mentioning Jack's uncles such as Michael who Jack stated that he met in the form of his counterpart that tortured him as Lucifer states he was tortured too. Jack was then introduced to Gabriel who he noted he had already met and Gabriel warned his nephew not to trust anything Lucifer is saying, this left Jack pondering.
On the road, Jack was amazed when Lucifer kills an attacking group of angels and reveals that he only pretended the handcuffs were working before melting them off. Jack believed he could finally defeat angels by using both his father, uncle, and soldiers but was repeatedly told not to since Sam and Dean who had a plan.
Afterwards, Jack took part in the liberation of Arthur and Charlie, killing two angels and the humans wanted to evacuate to the other world. The others work on a bus to transport everyone but Jack wanted to kill Michael before he left. As he tried to leave, Sam stopped him and tried to talk him out of it but Jack was only swayed when Lucifer intervene since his plan was dangerous and he conceded.
At the sight of the rift, Jack was one of the few to cross over and returned to Earth. As everyone celebrated, Jack was the only one who was disappointed as he was told by Sam that Lucifer was killed by Michael.
In Let the Good Times Roll, Jack joins the Winchesters and Castiel on a werewolf hunt. During the hunt, Jack uses his telekinesis to hold the werewolves in place, allowing the Winchesters to easily kill them. Afterwards, Dean expresses hope that with Jack's help, they may actually be able to win over the forces of evil in the long run and Dean comforts Jack over his nightmares about the people that Jack has lost.
After the murder of Maggie, Jack is left distraught by his inability to protect her. After learning that Maggie was seeing a boy named Nate, Jack teleports to the gas station where Nate works and assaults him and attempts to strangle Nate against the cooler. Jack is only interrupted when Dean is forced to shoot him to get Jack's attention. After the Winchesters point out Nate's innocence, Jack departs, further distraught by his actions.
In the nearby forest, Jack remembers everyone that he has hurt while literally beating himself up for it. To Jack's surprise, he is visited by Lucifer who reveals that Sam left him behind in Apocalypse World, but claims not to hold a grudge. Lucifer entices Jack with the idea of leaving for the stars together as father and son which Jack agrees to, but asks Lucifer to resurrect Maggie first, an act that Lucifer reluctantly performs.
That night, as Jack prepares to depart with Lucifer, he receives a prayer from Sam that the Winchesters are in danger. Jack returns to the bunker in time to save Dean from an attack by Michael. Enraged, Jack severely injures Michael to the point that his eyes and ears bleed. Before Jack can kill Michael, he is interrupted by the appearance of Lucifer, exposing Lucifer's deal with Michael. Sam further reveals that Lucifer was the one who killed Maggie and Jack forces his father to admit the truth. Enraged, Jack orders Sam to leave him to deal with Lucifer and effectively disowns his father. Stating that he only wanted Jack's power, Lucifer opens a slit in Jack's throat with an archangel blade and steals his grace, leaving Jack powerless. Lucifer teleports away with Jack with Sam grabbing on for the ride.
In an abandoned church, Lucifer beats on Sam and tries to strangle him to death. Though Jack tries to convince Lucifer to stop as his son, Lucifer simply beats on Jack as well, stating that Jack has lost his chance and he can have more kids. Lucifer, now super-charged by Jack's grace, decides to force Sam and Jack to fight to the death, with the winner being allowed to survive to try to find a way to stop Lucifer from destroying all life in the universe and remaking it in his own image. Though Sam offers Jack Lucifer's archangel blade to kill Sam so that Jack can live, defeat Lucifer and regain his powers, Jack claims that he can't beat Lucifer, but that Sam can. In an act of self-sacrifice, Jack begins stabbing himself with the archangel blade, telling Sam that he loves everyone.
Before Jack can complete his suicide, Dean arrives, now the vessel of Michael. With Dean in control and Michael powering him, Dean battles Lucifer as Jack and Sam watch, ending with Dean killing Lucifer with an archangel blade. In the aftermath, Jack joins the Winchesters in staring in amazement at Lucifer's corpse before Michael suddenly betrays his deal with Dean, takes full control of his body and disappears.
In Stranger in a Strange Land, Jack was being taught how to actually fight with Alternate Bobby before being knocked to the ground. While discussing with Bobby on how he never actually had to learn how to fight when he used to have his powers and how different the experience is, Bobby reassures him that fighting did not come easy to him neither and encourages him to keep training before they resumed their sparring session.
Later after learning that Castiel was captured by demons, Jack joined the team to rescue him even though he was not ready in his training. Jack and Maggie were captured by the demons during their attempt to ambush the demons while Sam went in to distract them. During the fight with the demons, Jack was knocked down and beaten by the demons until Sam orders the demons to leave and abolishes the title of Ruler of Hell. Back in the bunker, Castiel goes into Jack's room while Jack is wallowing in self-pity of his own powerlessness and uselessness. Castiel reassures Jack that his grace would regenerate in time and that even if Jack doesn't have his powers, he still has his family, although it does not work as Jack is still frustrated by how without his powers, he cannot stop Michael.
In Gods and Monsters, Jack is ordered by Sam and the others to stay back in the bunker, which he seems to agree with. Jack soon goes over lore about his grace returning, he looks up Archangels before Castiel tells him it might take longer because of his human status being a factor. Jack is angry since Michael could cause serious damage and he can't stop it.
He later sneaks out and visits Kelly's parents, his grandparents. Its revealed that Kelly named her son after her father who is also named Jack. Kelly's parents tell Jack that Kelly had claimed she was going on a long trip and would contact them when she could and they are unaware of her death, showing Jack pictures of his mother as a child. Kelly's parents are aware that she was pregnant, as Jack tells them how Kelly had a son who she loved deeply and about all the things Kelly did that made him feel safe and wanted, even from the womb. Kelly's mom tells Jack that he kind of looks like Kelly and shows him a picture of a young Kelly on a horse who has a resemblance to Jack. He doesn't reveal their relation though tells his grandparents he'll pass along the message before hugging his grandmother.
Jack returns to the bunker and Castiel is irate at his reckless action though stops after Jack states he needed clarity. Jack soon asks about a way to stop Michael, Castiel tries to consider one while Jack states they might have to kill him, something that causes Castiel to argue with his statement as Dean would die too. However, Jack states Dean would rather die than suffer at the Archangel's hands.
During The Scar, Jack and Castiel are reunited with Dean who they are happy to see but question on what became of Michael and the latter's intentions. Dean responded he had no idea and went to rest, as Castiel confirmed to Jack it is Dean.
Jack is present when Castiel helps a hunter with a cursed girl, Jack talks to her and she asked if Castiel was his father, Jack responded that he was "one of them" and assures her that he will save her. While secretly planning to leave, Jack leaves a note for his friends to find before seeing that the girl who was cursed has succumbed. Jack mourns her though gets an idea, he examines the witches' corpse and deduces her spell is still in effect and spots the necklace she was wearing. He destroys it and the essence goes back to the girl who is resurrected and returned to normal. Castiel congratulates Jack and promises to put in a good word to Sam and Dean about going on a case, to Jack's joy. In his room, Jack was seemingly sick and told Castiel, he was having his first cold. However, after Castiel leaves, Jack coughs up blood and is shown to have been doing this frequently.
In Optimism, Jack has grown tired of resting in the bunker and tells Dean that Sam is on a hunt with Charlie Bradbury while Bobby and Mary are on leave. He talks with Dean about a recent case and asks to join him since Cass said he was making progress. After some reluctance, Dean agreed and they traveled to a town where Jack seemed to be inept but this changed as he improved. They got some info on a recent librarian named Harper Sayles.
After Dean tried to asked Harper questions, Jack was able to get him to leave while Harper took an interest in him, as a way to get her attention. At the apartment, Jack talked with her and she tried to entice Jack but he was called by Dean and he told him that she wasn't a demon but that she may like him, to Dean's disbelief. Jack was still suffering from his cough and covered it up with an excuse. Soon, Dean arrived while chased by Harper's old boyfriend Vance who was now a zombie. Jack filled Harper in on his and Dean's occupation before he left Dean to handle the threat while he ran off with Harper.
Jack and Harper hid out in the library, they saw Vance walk by and Harper went to lock the door but Vance saw her. Harper then revealed her true nature, as she set Vance on him and told Jack her history while mentioning she may have liked him but put it aside for her only "love". Dean arrived with him and Jack both telling Harper and Vance, their supposed love was a sham and attempted to get through to them but were ignored. After Vance was restrained, Harper took the opportunity to run while leaving Vance to be put to rest.
Jack later talked with Dean about the case and was congratulated about his progress, before his sickness acted up. He coughed up blood again but this time it worse, Jack soon collapsed as Dean tended to his unconscious form.
During Unhuman Nature, Jack is tended to by Castiel but he is unable to heal him and his condition worsens. He is rushed to a hospital and the doctors diagnose his bodily functions as shutting down. The Winchesters and Castiel discharge Jack, they search for ways to help. They contact Rowena who at first is against helping the son of the devil, she is swayed when Jack talks to her and thanks her for her part in the Exodus from Apocalypse World. Rowena soon does her part and revealed that because Jack's grace is what holds his human and angel halves in balance, it is coming into conflict with each other, since his grace has been diminished causing his body to shut down progressively. Rowena determines the only way to revert that is for the Nephilim to recharge their grace. Realizing his days are limited, Jack resolved to get enjoyment out of his remaining time, as Dean decides to help him by teaching him how to drive, by using the Impala and Jack is excited by it. He soon has Dean take him fishing, something that Jack knew was the one thing that Dean had enjoyed doing with his own father. Later on, they return to the bunker after Castiel met a Shaman who possessed a vial of Gabriel's grace, which they intend to use to recharge Jack's to hasten his recovery. However, Jack's body ultimately rejects it and his condition worsens and it is determined he is dying.
In Byzantium, Jack is slowly dying and resigns to his fate but Dean is not accepting of it and leaves the room. Jack asks Sam to tell Dean it'll be fine though Sam wants Jack to do it as he succumbs and dies. Sam told Dean and Castiel of it, with them being sad at the untimely end.
After his death, Jack ascends to Heaven where he spends his time with his loved ones but realizes something is amiss and leaves his personal heaven. He is soon chased by a black ooze. He manages to elude it and goes into the personal heaven of his mother and finds Kelly enjoying an eternity of chasing her dog as a child before he makes his presence known and reveals his identity as her son. He watches as she turns back into her adult form and they embrace with Jack being happy to finally meet her. When she expresses confusion at his appearance, he explains he rapidly aged himself. Jack soon tells Kelly that she is dead and in Heaven while she sadly accepts it before realizing Jack is dead too and she breaks down at his fate. Jack assures its alright and tells her of a lurking threat after him. Kelly hides him before Castiel appears and explains of what is after Jack, telling the boy that because of his angel heritage that he will be sent to The Empty. He then informs him that he and the Winchesters are working bring Jack back to life, which is why he present as Jack is surprised he'll be brought back. However, Duma appears but she is revealed to be possessed by the shadow, Jack watches as Castiel is overpowered and Kelly steps in to defend him but is knocked aside. Seeing his mother in pain, Jack attempts to attack but is easily defeated as The Shadow prepares to claim him but Castiel offers it a deal his place for Jack. A worried Jack tries to protest but Castiel succeeds in bargaining with the Shadow who makes the terms for claiming him before leaving. Jack angrily questions this as Castiel tells him, he did out of love for him and is at peace with his choice. Jack then promises to keep Castiel's secret as Castiel receives word the spell is finished. Jack seemed hesitant to leave his mother but Kelly implored her son to live a full life and thanked him for letting her share a memory with him. With this, Jack returned to earth and read a spell that allowed his soul to return to his body, completing his resurrection. The group celebrate Jack's return and prepare to go after Michael since the angels provided his location to Castiel.
As of The Spear, he is at the bunker where he is wandering to the kitchen and met by Castiel. He confides about the latter's deal with The Shadow and thanks him for his sacrifice and they go over on how to stop Michael. Jack answers the call from Arthur Ketch who reveals he sent the Hyperbolic pulse generator through the mail. Jack also noted they needed to find Alternate Kaia still having her spear He and Sam go to the Kanas city post office where they are intercepted by Michael's monsters who incapacitate Sam and abduct Jack. Michael himself appeared to Sam and destroys the Hyperbolic pulse generator. Jack is taken to Michael's headquarters and placed in his office, where he meets with the Archangel. Michael offers him a position in his army by telling Jack that they are family with their powers and can make the world theirs if they sided together. Jack is not fazed and denounces him as a monster as Michael tells him that he'll watch everything die before he leaves.
He later sits still captive until Sam arrives after fighting through enemies to get to him. Jack and Sam meet up with Garth and go to the garage to await Castiel and Dean's arrival before Garth goes berserk and lashes out at Jack, nearly killing him until Sam knocks Garth out. The others arrive with Castiel healing Jack and they load Garth up in the trunk of the Impala and leave to confront Michael with the Spear. They face Michael who effortlessly overcomes their attempts to attack him before Dean attacks him with the spear. As Dean overpowered Michael and readied to kill him, something Jack encourages but Dean hesitates and Michael's vessel falls dead while Dean breaks the spear, before it is revealed Michael took control of him again. Jack is horrified as Michael explains when first having Dean as a vessel, the latter resisted in accepting it and he decided to leave him but "left the door open a crack" in his mind so that he could return at will. Michael tells Castiel that he waited to break Dean's spirit and has now locked him away to prevent his interference. He taunts Team Free Will by telling them, nothing stands in his way now and his monsters are on the prowl awaiting his signal, which he soon gives with a snap of his fingers.
During Nihilism, Jack is worried at Michael snapping his fingers, to unleash his monster army out on the city. Jack is tortured by the Archangel who reveals that he will destroy everything, Jack watches as a distracted Michael is captured by Sam and Castiel who place Supernatural Handcuffs on him. Michael is undaunted as his monsters start pounding on the door, forcing Jack and Cass to guard the door from the attack. He watches Sam calls for a Reaper to appear. Jack and Castiel couldn't see the reaper Violet and questioned him on this, though is surprised Michael noticed her presence. Soon, Violet gets orders and the group are transported to the bunker. Jack stayed with Maggie and the other hunters to fight off the monsters but struggled to keep them at bay. Seeing the chaos, Jack taps into his soul and uses the power of his soul to disintegrate the monsters. Afterwards, Dean traps Michael while Jack is lectured by Castiel on using his powers in current condition and calls it dangerous. Once Castiel is thanks Jack for his act since he saved the day.
In Ouroboros, Team Free Will 2.0 are out on a hunt with Rowena for an elusive gorgon named Noah Ophis. At a diner, Jack's illness acts up but he uses the Enochian magic to keep his condition in check. After Sam receives an update from Maggie who tells him that the lore states that Gorgon can only be killed via decapitation with a silver blade. The group also learned that its foresight on humans doesn't work on Jack or Castiel because of their angel status. Using this to their advantage, they gather necessary material for a trap. For this, Jack is transformed into a dog and goes to a vet where he gains the ingredients for the cure to the paralysis before they after the deity. When Noah paralyzes Castiel, Jack tends to him while Sam and Dean fights. When Noah tries to escape, he is promptly beheaded by Jack, who slipped away in the confusion and ends the Gorgon's spree. Seeing Castiel unresponsive, Jack uses his powers to heal Castiel. At the bunker, he has taken Noah's pet snake and Castiel once more scolds Jack for his carelessness and soon gives details on how they as cosmic beings will soon lose those they care for in time.
When Michael possessed Rowena MacLeod, he went on a killing rampage and slaughtered all the hunters present. Jack witnessed Maggie being the last victim that was killed by smiting, as he was horrified to see the Archangel free. Jack witnessed Michael torturing the others and spoke out against this. Michael turned his wrath on him but Jack once more used his powers to have a chance and stood against his enemy. Jack declared himself as both a hunter and Winchester as he seized Michael by the head and ejected him from Rowena. By doing this, Jack freed the others of their torture and they witnessed Jack declare that the Archangel is finished as he incinerates Michael.
As he destroys the threat, Jack absorbs Michael's grace and tells the others that Michael is dead and he is himself again before he shows his wings as proof of his full powers returning to him.
In Peace of Mind, Jack is mostly silent with his restored powers and his mood towards the hunter's funeral. Jack assures Castiel that he is fine but Castiel isn't too sure and has Dean look into it. Dean notices Jack is behaving oddly with his new pet snake and takes him on a trip to see Donatello who Dean calls their expert in a lack of soul. Jack learns his great aunt took Donatello's soul and asks him how he has lived without it. He hears Donatello detail soullessness in general with Donatello describing himself like a galaxy: bright and shiny on the outside, but with a large black hole on the inside. Donatello then tells him about the emptiness he feels, the lack of pity, emotion and humanity that comes with it. Jack admits that he doesn't feel nothing, but he also doesn't feel the same. Donatello tells Jack how when he wants to blend in, Donatello thinks "what would Mr. Rogers do?" as Mr. Rogers is the best man he knows. Hearing this, Jack tells him that Sam and Dean are the best men he knows, Donatello suggests that Jack think "what would the Winchesters do?" when he is unsure of himself.
When Donatello leads Jack back to the Impala, Dean asks if Jack still has a soul. Donatello brings up the philosophical nature of the question before admitting that while Jack's "been around," if he says he's okay, Jack probably is. When Dean asks if Jack is like Donatello, Donatello states that Jack definitely is not because Donatello is a Prophet while Jack is probably the most powerful being in the universe and its impossible to know what is going on in his head. After heading back to the bunker, Jack comforts his pet snake and tells him that he'll be with his master before incinerating it. This was witnessed by Castiel who worried if Jack was further gone than thought.
During Don't Go In The Woods, Jack hangs out at the bunker going over books in the library when Sam and Dean tell him of a case they are going on. They request Jack stay at the bunker and do shopping for them. Though seemingly annoyed, he agrees. Jack went into town where he notice the store closed. He is met by three teens who recall his status with Sam and Dean, who they ask are on a monster case. Jack tries to deny it but the trio tell him that they know of the brothers' activities and ask him to hang. Jack agrees and tells them more about monsters and they invite him to their hangout. Jack appears at the spot by bringing books about monsters and Eliot is amazed by the details. Soon he shows from the angel blade, which he played with as well as his powers but he accidentally stabs Stacy in the stomach and Max comes to her side as Stacy is in pain. Jack is stopped by Eliot from approaching them and Max nearly calls an ambulance but Jack feels guilt for causing a second accident uses powers to heal Stacy, saving her life. However, the teens are now scared of him and his powers. They tell him to stay away from them and leave the area. Jack returns to the bunker where he meets Sam and Dean, they reveal that they were unsure of whether to bring him on cases, since they had been wary of his returning powers and potential accidents. However, they have decided to bring him on cases but he can't use his powers until the right time. Feeling guilt for his experience with the teens, Jack withholds this and agrees.
In Game Night, Jack takes part in the interrogation of Nick and tortures him to get information on the lost Donatello. After realizing that Nick is resurrecting Lucifer, Jack travels to the cabin where Nick is performing the ritual, sends Lucifer back to the Empty and brutally kills Nick. On Mary's request, Jack heals the badly injured Sam, but Mary is disturbed his actions. When Mary confronts Jack about his lack of soul, Jack yells at her to stop before suddenly calling out her name in a breathless voice.
In Moriah, he breaks out the box and blasts everyone away for lying to him and leaves the area. Jack wanders and tells people to stop lying, with his powers causing everyone to tell only the truth. He returns to the house of his grandparents but Mrs. Kline reveals that she has discovered his deceit on Kelly's whereabouts and shouts at him to tell the truth. Jack gets angry and reveals his powers, silencing her but he doesn't harm her because he didn't want to replicate the event of Mary and simply leaves. When God returns, he stops Jack's act and tells the Winchesters to stop Jack permanently.
Jack arrives at a cemetery where he finds Castiel sitting before they talk on his empty feelings and how Jack now feels like no matter what he tries to do, he only hurts people. Soon Dean arrives to confront him, Jack knocks Cass away when he tries to intervene. Knowing what Dean would do, accepts the outcome. However, Dean relents and this is met with outrage by God, who Jack is surprised to meet. Jack watches the argument between his grandfather and the Winchesters with God even offering to bring Mary back if Dean kills Jack, but Dean refuses as he knows Mary wouldn't want that. As the confrontation continues, God snaps his fingers, smiting Jack in a similar manner to an angel smiting. After God departs, the Winchesters and Castiel grieve over Jack's body, left on the ground with his eyes burned out and his burned wings spread around him, before the souls of Hell and zombies rise to cause chaos in retaliation for their actions.
In the Empty, Jack awakens and is greeted by the Shadow in form of a black viscous humanoid figure that forms a smile upon its face at the sight of him. As Jack questions what has happened, Billie appears and tells him that they should talk about that.
In Back and to the Future, Castiel carries Jack's corpse away from the horde of zombies when he and the Winchesters flee into a mausoleum. Jack's body is subsequently taken as a vessel by the demon Belphegor who takes to wearing a pair of sunglasses to cover up Jack's burned out eyes. Though the Winchesters and Castiel are unhappy, they reluctantly agree to allow Belphegor to use Jack's body as a vessel to help them out until he can find a new vessel.
In Raising Hell, Arthur Ketch is surprised to see Belphegor, mistaking him for Jack which Belphegor comments he gets a lot. Sam and Dean are forced to tell Arthur and Rowena MacLeod that Jack is dead and Belphegor is a demon using his corpse as a vessel. Both are noticeably saddened by the news of Jack's death while Arthur finds the situation somewhat awkward as he has been hired by Ardat to kill Belphegor.
In The Rupture, Castiel continues to find it hard to work with Belphegor who continues to use Jack as his vessel. After Ardat reveals that Belphegor is trying to take power in Hell for himself, Castiel beats Belphegor down and knocks off the sunglasses. Belphegor tries to claim to be a resurrected Jack, but Castiel sees through it and smites the demon. The smiting burns Jack's body, turning it into a charred skeleton.