Jason is Michael's elder son and brother to Mat. He and his family abandoned town when it was hit by the alien forces and were forced to retreat to their grandfather's farm where the danger wasn't that great. Jason is more thoughtful and level headed than his brother, who is more ruthless and acts out of emotion. Even when Michael suggested they should abandon their house and the search for their mother, Jason agreed, knowing this was the best for everyone. Jason is adept at using firearms and serves along the rest of his family under William Harris' orders. At first, Jason is one of the only capable of going on supply trips, as he is both young, agile and good at using  weapons, however when Ray is found, he replaces him and jason stays more at camp where he trains and goes to other missions with William and the others who serve by him. After Nicholas' death though, he is once more enlisted as a runner, and is forced to work with Ray, something neither of them likes. Eventually though, they learn to like each other and their friendship grows ever since. After a while, Ray apologises for getting between him and Nora, and explains he didn't know they were together. Jason forgives him and says he put that event behind him, and the two get along ever since

In one of his first conversations, he asks Nora if she knew anyone before the invasion, and she said that her father had heard some of their names, as they all worked in universities or research facilities, but he hadn't met anyone in person

After Michael's death, Jason nearly destroys everything he has accomplished in his life. Before Michael's death, Jason was appointed to lead a small army against an arian outpost. His mission was to look out for the outpost and make sure they are not aware of the attack on their headquarters. However, Jason manages to wipe it out completely taking a chance he is given. The ambush is successful, and the arians are wiped out. Jason rushes back to assist William with the remaining forces, proud to have completed such a feat. One of the women there (the one he is going to cheat on Nora with later) tell him that the arian brotherhood was just a part of a network of escaped convicts. Jason hurries back to inform William that they have a far greater problem. When he returns from the mission he was sent in, he finds that the arians have called for reinforcements greater than anyone could have imagined.Then he runs to find his family, and finds Mat, who starts crying the moment he sees him. Jason asks what happened, but Mat is too shocked to talk. His uncle, George takes him a little further away to explain what happened. Jason is seen from a distance, shocked as he hears the news, trying to go and see his father. George tires to stop him, but Jason breaks free. Norman, seeing the whole scene, tries to comfort Jason, telling him that nothing good is in there for him to see, but Jason pushes him away and enters the room his father's body was kept. He breaks down as he sees the brutality, and George follows behind him shortly to comfort. Nora is also informed and goes to see and stand by him, but he is indifferent to her and leaves in his house, where he stays alone.

Over time, Jason becomes even more distant to everyone. When William and the others talk about what to do (after James wakes up), Jason attends and wants to attack the cartel. He even goes as far as to say that he will go all by himself, arguing with everyone there who suggest they should submit, seeing as they fought a war they could never win. William, Nora, even James all try to convince him otherwise, but he blames them all for Michael's death for not doing anything. Ηe then storms off, calling everyone a coward. When he gets home, Mat goes to see him, and Jason tells him that he is going to attack the cartel. Mat says that if he is going, Mat is going too. Jason stops him and says he is a coward who let their father die. He won't take him with. Mat tries to excuse himself, saying that he was tied up, but Jason doesn't listen. "Get out", he tells his brother and Mat exits the house in tears. Jason packs up some weapons and exits the house, finding Nora wait outside. He says he doesn't want to talk, and he is going to leave no matter what she does. Nora says she won't let him get himself killed, because she cares about him. He replies they are breaking up and that she doesn't have to care about him anymore. Then he tells her to get out of his face. When he approaches the gate, he draws his gun and orders the guard to open the gate. William appears and tells the guard not to, at the same time grabbing Jason's gun. Jason shoots a bullet in the air, and William headbutts him, forcing him to let go of the gun. Jason goes for an attack, but William hits him in the face with the hilt of the weapon, making him fall on the ground. He then calls him pathetic and a drunk, and that he is a disgrace to what his father would want him to be. Jason replies that thanks to him, his father will thankfully never be around again to see what he has become. William then points the gun at him, and says that he gets it. "You blame me for your dad dying. That's fine. Maybe you are right. Maybe I am responsible for his death. Maybe I could have saved him if I tried to. But do you know what would I have then? More bodies. Maybe all of us would be dead. Your brother would be for sure. Your grandpa. They both had a rifle aimed at their heads. Would you like that?". Jason cuts him saying that nothing he say will change his mind. It's his life, and if he wants to go, nobody will stop him. "I will stop you. And I 'll kill you if I have to. It's a tough choice. Like not doing anything to save your dad was. Like working with.. under, those monsters is. But I 've made all those other calls. To save everyone. Or to save as many as I can. I can't save everyone, but I will save as many as I can. Now I want to save you, but if I can't, if you 're gonna do something stupid to endanger everyone here, I will kill you before you do that. If I have to kill you, I 'll make that call too. This is why I 'm the leader. This is why I got you all here. Because I make the tough calls. And I get to live with them. I saw my best friend die in front of me, and at the same time I did nothing because I knew that my children, his children, and probably lots more would have died. I took that call, and I must live with it. And I will die with it. So hate me. I can live with that too. But if you go out there guns blazing on the criminals, they won't see the attack as being just you. They will come back. And this time, they will kill us all. And your father's death would have been for nothing.". Nora then arrives and takes Jason home, while William leaves. Nora helps Jason stand up, while he pushes her hands away, and William is falling in bed, Christine hugging him.

For a while later, Jason's condition only worsens. He takes up drinking, once he randomly started shooting in the middle of the community and others were forced to restrain him before he attracted more leechers. He also cheats on Nora with a random girl from the community, and asks her to join a threesome, and he hits on Joleene hard, and insists after she turns him down. After that he also gets in a fight with Danny, since when he hit on Joleene he almost attacked her, as he pushed her on a sofa, and tried to kiss her without her wanting it. Nora then breaks up with him, after taking her father's advice. He tells her that she should stop thinking why Jason does all these stuff, and instead ask herself why she does all these things for him when there is no future. Jason is also forced to talk to Christine, but he mocks her about her cancer and the ones she lost and she stops treating him, stating that it's futile if he doesn't want to be saved. She also can't stand him blaming her for Michael's death, as she is also torn by his death because they were together. William has also kicked him out of the military and tells him he is lucky he is allowed to live in the community without providing anything. Jason is living in a house alone, and only Mat visits him to bring him supplies. When James gets better, the first thing he does is visit his grandson, and Jason breaks up and lets everything out. He says he is messed up, and and has led everyone away. He says he fears being left alone, and he has nothing else to live for. James hugs him and says he will always be there for him, as will his brother. Jason denies this, saying Mat will never forgive him for what he said to him, but Mat appears from outside and says he is one of the few family members he has left, and doesn't want to lose him. Jason apologises and this is the first step to becoming a great man once again. He later wins Nora back

Later, in the Deadlands, he and Nora adopt at least one child as Nora is unable to have children of her own. The boy's name is Mike, which is short for Michael, Jason's deceased father. First they adopt Jonnie's children

At some point (after the war), Jason opens up to Nora about the people he has killed. He says it might be weird, but he thinks about them, about how they could have changed, become good people, and live together as a group, and how he is the one that forbid them from doing so. He feels bad about it, and he gets that he did what he had to do, but still... Nora replies that this might be true, those people might become good folks someday, but right now, they are the ones who survived, and they became good people.

In the final battle, Nora and Mat die before Jason's eyes, and Jason is surrounded and alone, because as he kneels down to check on a shot Nora, Mat dies at that moment and he freaks out. When all the others die too, the aliens surround him and Jason says "fuck you all" and shoots himself in the head, remembering when he told his grandfather that he doesn't want to be left alone.

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