Justin is a young drug dealer in Fruit's crew. He is identifiable by his baseball cap, which he wears sideways (which was the subject of a brief conversation with Thomas "Herc" Hauk and Ellis Carver).
He discovered the body of Stanfield drug dealer LaTroy with his colleague Jamal and the two fled the streets in fear of their own safety. Toward the end of season three, he gets involved with Dennis "Cutty" Wise and his boxing gym. At first, he resists Cutty's attempts to teach and instill discipline, but he eventually settles down and is seen sparring with (and losing to) a smaller boxer from another gym.
Justin continues to attend Cutty's gym and train as a boxer. As the gym grows, Justin develops a superior attitude to more casual users of the equipment. He provokes a fight with Michael Lee over use of the heavy bag when he is preparing for a fight but Cutty calmly breaks the pair up. Justin became more accepting of Michael over time and the two attended a professional boxing match along with Cutty. It can be assumed as he is no longer seen, that Justin was successfully saved from the streets by Cutty's efforts.