“What’s the point of being a cosmic being if everyone I care about is just gonna… leave?”
First introduced at the end of Supernatural‘s 12th season, the Nephilim Jack was made out to be the biggest bad the Winchesters would ever face. Although he’s the literal Spawn of Satan, Jack, half-human and half-angel, quickly became part of Team Free Will and an instant fan-favorite — an honorary Winchester. In the few seasons Jack has been on the show, he has been through almost as much as the other characters. He’s struggled with whether he’s good or evil, constantly tried to prove to himself and others that he isn’t his father, and made the wrong choices for the right reasons. Despite this constant struggle, he’s made himself a new family consisting not only of the characters surrounding him but the fans who love him and want to protect him at all costs.
Although Jack wasn’t actually introduced until the season 12 finale, half of the season had been leading up to his birth. Everyone was talking about how powerful he’d be and how he needed to be stopped at all costs. Kelly Kline believed in her baby and still wanted to have him, even if it meant risking her life to do so. She was convinced Jack would show her and Cas paradise and how good the world could be with him in it. That made Cas want to protect this unborn powerful being, even though Sam and Dean didn’t agree. When Jack is born in the finale, as predicted, Kelly is killed. The only time fans see Jack is at the very end of the episode when he is in the corner of the room and his eyes are glowing yellow, saying “Father?” It’s a very short appearance but a powerful entrance that left fans uncertain of the Nephilim’s nature, good or bad.
When season 13 starts off, Jack is trying to adjust to his new existence. He gets help from Sam and Dean who take him under their wing; however, he struggles with having abilities and losing his mother. He doesn’t quite yet know the differences between bad and good, though he’s trying to understand. The Winchesters try to help Jack master his powers, and soon Jack overhears them talking about Cas. Jack plays a role in Cas’ resurrection — their connection is due to Jack having chosen him as his father in the womb. When Cas returns, Jack feels like he has someone who understands him. He knows Cas, he can trust him. The first time Jack kills someone by accident is in the sixth episode of the season and it changes him. Throughout the season, Jack tries to get a sense of who he is, and he’s traumatized every time he does something bad — even if it is by accident.
In order to try to master his powers, Jack leaves the bunker. In the episode “The Bad Place,” Jack seeks out a Dreamwalker to help him get to Apocalypse World so he can find Mary. Sam and Dean catch up to him and the Dreamwalker, Kaia. Jack tells them he saw Apocalypse World and Mary, who’s alive. He uses his powers on Kaia so she can Dreamwalk, but she ends up sending Jack to Apocalypse World alone. In the following episodes, Jack rescues Mary and they fight angels to protect a human colony. Wanting to free the world from Michael’s reign, Jack, with Mary’s help, forms a resistance composed of humans to stand against the angels. After everything he’s gone through, he now feels like he really has a purpose and can save all these people.
Once reunited with Sam, Dean, and Cas in “Exodus,” as well as meeting uncle Gabriel and father Lucifer, all Jack wants is to know more about his family, wishing to get to know his father, hear him out, and maybe get on good terms with him. He even thinks that with Lucifer’s help, they could defeat Michael. In the season finale, however, Lucifer offers to take Jack to the stars where they could go on a father-son journey across the known universe. At first, Jack accepts, happy he’s finally bonding with his father. However, he soon realizes Lucifer’s true intentions and malicious nature and disowns him. In retaliation, Lucifer steals Jack’s grace, taking all of his power and making him human. Later, in the big church showdown, Lucifer wants Jack and Sam to kill one another. Sam tells Jack to kill him so he can get his powers back but Jack refuses. He nearly sacrifices himself instead of killing Sam, believing Sam can do more good than him. Luckily, both make it out alive. The boys took a chance on Jack because they could see that he’s not like Lucifer: he’s more like Kelly. He’s curious and full of wonder. Every bad thing he did, he did it with good intentions. He wants to help people, not hurt them.
Jack, struggling with the aftermath of losing his grace, tries to adjust to life as a human. All he wants to do is help people, no matter the costs — even if it means killing Dean to get rid of Michael. He becomes sick in the beginning of season 14, passing it off as getting his first cold since he’s now human. Soon, Jack starts to become seriously ill since his grace was the thing keeping his body intact. After his body gives out and he dies, Jack meets his mother for the first time in Heaven. While there, he’s pursued by The Shadow who sought to claim him for The Empty. With the help of the Winchesters and Cas, Jack is resurrected and returns to Earth. When Michael uses Rowena as a vessel in “Ouroboros,” the guys are almost powerless to stop him. Michael begins to taunt Jack, telling him that he’s only a child. Jack, knowing that he’s burning through his soul, uses up all the power he has and kills Michael, but not before telling him that he isn’t a child: he’s the son of Lucifer, he’s a hunter, he’s a Winchester. He consumes Michael’s grace, getting his powers back. But at what cost?
Jack isn’t completely in control of his powers just yet. Wanting him to get some rest and not really trusting him with his abilities, Sam and Dean leave him at the bunker while they deal with a case in the episode “Don’t Go in the Woods.” Jack makes some new friends while trying to buy some groceries, and he starts hanging out with them. Jack shows off his powers to his new friends, twirling around a knife with just his finger and accidentally stabs someone. Luckily, he’s able to heal her, but he realizes that he’s not as in control of his powers as he thought. He doesn’t tell Sam and Dean what happened, not wanting to worry them. The following episode, “Game Night,” proves Jack’s strength. After Sam and Dean leave Mary and Jack alone in the bunker to save Donatello, the two soon have to go after Nick, who is trying to resurrect Lucifer. When they get to Nick, Jack uses his powers to viciously burn him. Mary, not yet wanting to talk about what happened, tells Jack that Sam’s hurt and to go help him. Jack heals Sam and when he returns to Mary, she tries to carefully talk to him. She’s afraid of him; she doesn’t like what he did and she knows Sam and Dean won’t like it either once they find out. Jack wants to be left alone, telling Mary over and over again but she doesn’t listen. She gets closer to him and Jack, frustrated, accidentally ends up using his powers on her, resulting in her death.
Jack tries everything he can to bring Mary back before the guys can figure out what happened. He flies all over the world, grabbing ingredients and getting Rowena’s help, but it’s no use: he can’t bring her back. Jack sought to redeem himself by creating new angels, but it didn’t help. Sam and Dean know that Jack’s powers are out of control and in an attempt to help him, they trick him into getting in the Ma’lak box. Jack manages to escape the trap and roams Earth until Sam, Dean, and Cas catch up to him. Jack admits that he doesn’t feel anything. Sam and Dean intended to kill him, but they stop themselves. However, God returns to Earth and kills his grandson before Sam, Dean or Cas have a chance to stop him. Jack ends up in The Empty and comes face to face with Death herself.
When season 15 starts off, Jack is still in The Empty — but his vessel is now occupied by the demon Belphegor. Though the idea of a demon being in Jack’s body doesn’t appeal to Sam, Dean, and Cas, Belphagor sticks around for a few episodes in order to “help” the Winchesters. He is killed by Cas in Hell when it’s discovered Belphegor only wanted to gain power for himself, resulting in Jack’s corpse burning to a charred skeleton. Jack is only seen a few times throughout the first half of the season in The Empty, as Billie keeps him hidden until God leaves Earth after fully recovering his powers.
At the beginning of the second half of the season, Billie resurrects Jack once God is gone, telling him that he will eventually become strong enough to kill God and giving him a plan to do so. Cas, having gotten information from a police officer on Jack’s whereabouts, finds him killing and eating the hearts of Grigoris. When Sam and Dean return to the bunker after getting their luck back in “The Gamblers,” they’re surprised and relieved to find both Cas and Jack. He tells them about the plan: he must hide and not use his powers until he’s ready to defeat God. He cannot draw God’s attention to him.
The final episode that aired before Supernatural went on hiatus due to the Coronavirus pandemic, “Destiny’s Child,” showed Jack finding out where the Occultum, a mystical artifact created by God capable of transporting one to the Garden of Eden, was residing. Jack visits the Garden as Sam, Dean, and Cas try to keep away Hellhounds. His soul is restored in the Garden; when the team arrives back in the bunker, Jack remembers everything that he did while he didn’t have a soul, including killing Mary. He breaks down and Cas informs Sam and Dean that Jack has his soul back. Jack apologizes to them, begging them for their forgiveness for what happened saying, “Just please forgive me”.
Jack Kline started out as a Nephilim, but he became so much more than that. The second half of the final season seems to be building on the fact that Jack will have a great responsibility in taking down God in the Winchesters’ final showdown. Jack could very well be the key to creating his vision of “Paradise on Earth,” like one of our theories suggested. Now that Jack has his soul and his powers back, he seems to be ready to kill God. It won’t be easy, but with the Winchesters by his side, Jack is capable of anything. All Jack ever wanted was to help people and make the world a better place. Perhaps he can finally do this in the series’ end. There is no telling how big of a role Jack will play in these final seven episodes (that start airing on October 8), but we do know that he is ready for whatever comes his way.
“I’m not a child! I’m the son of Lucifer. I’m a hunter. I am a Winchester!”