|“||I saw your face. You couldn't kill anyone.||”|
Alison did not have a great relationship with her brother Jason due to his drug addiction and their mutual disrespect of each other's boundaries. Both had no problems going into each other's room, stealing and breaking each other's belongings. Some glimpses of that were seen in The Goodbye Look, My Name Is Trouble, and Surface Tension.
In one instance, Alison had fled one of her brother's house parties in tears, blaming her distress on Jason and his friends' invasiveness in her room, but left the particulars vague. However, while Alison is in jail, Jason shows comfort saying that "she couldn't kill anyone". After Alison is released from jail, and they found out they have a brother named Charles, they begin to grow closer as both stepping up to their dad together.
Spencer flashes back to one summer when Alison and the girls were lounging in the DiLaurentis' front yard. Jason had stormed out of the house, accusing Alison of messing with his stuff. She had retorted back sharply, mocking him and his friends for being stoners, and the other girls laughed. When Jason went back into the house, they questioned Alison whether she had stolen what he claimed she had. She admitted it gleefully. When Emily asked her whether she was worried that Jason would rip apart her room in search of his things, she mischievously replied that he would never find it, because when she wants something to stay hidden, it stays hidden. Alisons says she has hiding places everywhere, including the yard. She says thats why their secrets are so safe with her. Just then, a smashing sound was heard from inside the house, though Alison seemed unfazed.
There is a flashback of a time when Jason was having a party with his friends, and a distraught Alison had come to Spencer's house seeking refuge from the drunk boys at the party. Alison tells Spencer and Emily (who was there as well) that Jason's friends, or "animals", as she call them, are harassing her. Alison also says that Jason is counting on getting money from their grandmother, however if she told her about his wild partying she would write him out of her will.
When Jason had come looking for her on their mother's orders, unhappy to have to waste time looking for Alison. When he caught sight of the stick, he grabbed it from her and then threatened to hit her and Spencer let out a warning cry. When Jason turned around, Alison tried to whack her brother with the stick, but Jason moved quickly, and mockingly warned Alison that she wouldn't get a second chance.
Alison is seen sitting on her bed in October of 2008, writing in a notebook. When Jason enters without knocking, she immediately shuts the notebook. Jason glances at her move before demanding $20, stating that he was buying beer. Alison asks what he and his "stoner buddies" where doing. Jason tells her that they're making a movie, and that if he told her what kind of movie he'd have to kill her. After she forks it over, he then tosses her a package that was on the porch for her. Jason stares expectantly, hoping to see what's inside, but Alison is careful not to open it until he's gone.
Spencer tries to understand what is it that links Jason to her family, she flashes back to a night when Alison and Spencer were in Spencer's bedroom. Alison was reading a magazine and Spencer studying for a test. They heard Spencer's parents arguing downstairs and Alison asked what it was all about. Spencer told her that her father saw Melissa and Jason making out the other night and he's upset because of that. Alison wanted to open the door to hear what going on exactly and then said that Melissa and Jason would be "a match frowned upon by the gods." Spencer didn't catch her drift that Jason was her half brother also until over a year later.
Jason returns to Rosewood. He reveals to Emily that Mrs. DiLaurentis never liked Spencer and has a flashback. Jason was on the couch, when Alison and Mrs. DiLaurnetis walk through the door. They are talking about "A". Alison, who appears to be scared, says the notes are anonymous and Mrs. DiLaurentis tells Alison she thinks its Spencer. She tells Alison to defend herself and to smoke Spencer out. Jason reveals himself and Mrs. DiLaurentis asks how long he was there. Jason smirks in response.
Alison returns to Rosewood, and moves back home with Jason and their father, Kenneth DiLaurentis. That night, while Alison is in bed, she hears a noise from outside her bedroom. She jumps up, but lays back down. Her bedroom door slowly opens, it's Jason. He stands eerily in Alison's doorway, watching her sleep. The next day, Alison comes out and sits on the porch with Jason. Alison asks Jason why he hasn't asked her any questions, Jason replies that he wanted to give her some time. Suddenly, a dog that Jessica adopted named Pepe is brought to them from the animal shelter. Jason thinks it's a bad idea to keep the dog, but Alison does so anyway.
Later, Spencer and Emily shows Alison a bag from New York that they found in the trash bin outside her house. Alison tells them Jason was watching her sleep the night before. Alison suggests that it could have been Jason who hit her and that’s why Jessica suddenly disappeared so that she does not have to face Alison and tell her the truth. Emily suggests that Alison stay at Spencer's house, but Alison says that her father won't let her leave the house. That night, Spencer has goes over to the DiLaurentis house to distract Kenneth, and finds Jason sitting in the dark. Jason tells her he thinks his father is going to rat him out for being the one who kidnapped Alison. Suddenly, Pepe starts barking outside. Hearing the barks, Hanna, Emily and Aria run out the back of the Hastings house to find an arm sticking out from the ground. It's Jessica DiLaurentis. Spencer and Jason run over having heard the girls scream and Jason looks devastating upon finding his mother. Alison is later seen crying softly as her mother's body is taken away.
Jason [to Alison after she tries to hit him ]: Too bad. You're not gonna get a second chance, Ali.
Jason [to Alison and The Liars]: Stop messing with my stuff! You and the Powerpuff Girls just stay out of my room.
Jason: Just stay out of my room, ok?
Alison: No challenge for you and your little stoner buddies - all you need is something shiny on a piece of string.
Alison [to Jason]: $20 for a secret? You're so cheap.
Jason [to Spencer about Alison]: I wonder what kind of person she would have turned into. I mean, I see it with the kids I work with, and at first they're all attitude but you peel back the layers you usually find a person underneath.
Jason [about Alison]: I come into this room, I see her sitting at the piano or catch a glimpse of her going around a corner upstairs and I think to myself, "This is what it's like to live in a haunted house."