Justin Williams is a student at Blackwell Academy. He skateboards and Maxine Caulfield thinks he and his group look cute doing their tricks. He is friends with Trevor, despite the two of them competing for Dana Ward's affections.
Justin is a typical skater dude. A friendly and sensitive guy, he has a laid back attitude and seems to enjoy Max's company, particularly if she doesn't come off as a poser. He likes hanging out with his friends in Arcadia Bay and gets high often.
Episode One - "Chrysalis"
When Max is going to the bathroom the first time, she notices Justin talking to Dana.
Later, outside the main building, Justin is skating with his friends. If Max talks to him, she leaves Justin unimpressed that she can't name any skate moves like the nose-slide or a tre-flip. She can rewind time to use these buzzwords. When she does this, Justin is not as negative about her - pleased that she isn't a poser. He can have Trevor show Max the skate moves she named, and he can tell Max he used to spend time with Rachel and Chloe, though he can't seem to remember Chloe's name, describing her as Rachel's "punk friend." This memory lapse may suggest he was closer to Rachel, especially as he tells Max, "if anybody hurt her we'll get a skate posse and take 'em out with our boards."
He is happy to let Max take photos of him and his friends, and watch them skate.
Episode Two - "Out of Time"
Justin can be seen with Trevor in the Two Whales Diner, having breakfast. High, he seems conflicted in his feelings. He is both pleased for Trevor and Dana hooking up, and annoyed; he had a crush on her too. He seems to accept the situation. However, he and Trevor argue later in the morning, and get broken up by Joyce.
Episode Four - "Dark Room"
Justin makes an appearance in the Prescott Dormitory grounds in this episode. He and Chloe talk and catch up with each other. Justin clearly enjoys talking with her again, and she suggests hanging around with him and his friends at the park sometime. He also asks about Rachel, and Chloe tells him she's onto it. They fist bump, and Max comments that she can tell Justin is interested in Chloe. She also comments that Chloe seems to fit in with Justin and his crew.
He later appears in the boys' bathroom in the Blackwell swimming pool during the "End of the World" Vortex Club party. He stands by the sink, and Max can take an optional photo of his legs as skeleton graffiti. Upon talking to him, Max discovers that Justin is high, like most others at the party. He seems affectionate towards her, and asks why they don't hang out more. He confirms that he hasn't seen Nathan at the party.
Episode Five - "Polarized"
In the Sacrifice Chloe ending, he is among the people who are attending Chloe's funeral. In the Sacrifice Arcadia Bay ending, he presumably dies in the storm.
- Rachel Amber - Rachel used to hang out and with Justin and his skater friends prior to her disappearance. She stopped spending time with them after Rachel went missing. He hopes Rachel is okay wherever she is, and is willing to hurt anyone who would have hurt her.
- Chloe Price - Chloe used to hang out and skate with Justin and his skater friends together with Rachel. After Rachel's disappearance, the two distanced themselves, but their friendship is still intact, as she fist bumps him when entering the Two Whales Diner in "Out of Time", and talks to him in front of the Prescott Dormitory in "Dark Room". Though he can't remember her name, simply calling her "Rachel's punk friend", her punk-rockish appearance made a lasting impression on him. He found Chloe attractive and "hardcore". When they talk with each other in front of the Dormitory she suggests hanging around with him and his friends at the park sometime.
- Trevor - Justin and Trevor are best friends.
- Max Caulfield (Determinant) - He seems to enjoy Max's company, particularly if she doesn't come off as a poser. Max may impress Justin with her knowledge of skating moves since he really likes skater girls, and offers her to join them and take shots of him and his skater friends whenever she likes. He later states that he wishes to hang out with her more.
- Victoria Chase - He dislikes her because he thinks she is a snob.
- Nathan Prescott - Justin dislikes Nathan because he is part of the Vortex Club and thinks he is a "snobby douchebag."
- Chloe Price - Justin thinks Chloe is "hot", and according to Max's estimation while watching them talking in Episode 4, he's obviously interested in her.
- Dana Ward - Justin likes Dana a lot and wishes she was his girlfriend. In Episode 2, Trevor will mention that he had to tell Justin that he and Dana were together because Justin was into her too. At first, Justin doesn't seem too bothered, casually saying, "He got there first, so I snooze and I lose..." But if Max talks to him again in Episode 4, Justin will mention that he went to the party because Dana was there, but isn't enjoying himself because she isn't at the party with him. If Max asks him about Trevor and Dana, he will say that he tried to pretend he was okay with it, but that when he saw them together, he cried "like a little bitch." He will eventually say that he is just torturing himself, and he should leave the party to grind on his skateboard.
- The shirt saying "RAWS" Justin wears in "Chrysalis" is a reference to the 1975 shark attack thriller Jaws, directed by Steven Spielberg.
- Justin likes to listen to rock music, which is evident by the music playing where he and his friends hang around in front of the Main Building in Episode 1.