Lu is a middle-school runner with albinism who competes for the Defenders track team. He wears thick contact lenses and gold chains to project outward confidence. He also applies copious amounts of sunscreen before practice to protect himself from the elements. As he learns his mother is pregnant, he worries about his changing place in the family while simultaneously struggling to master the 110-meter hurdles without falling.

Gordon, often called "Goose," is Lu's father. He works as a recruiter for a rehabilitation center, handing out messages to people struggling with addiction to encourage them into treatment. In his youth, he suffered from a severe stutter that made him the target of intense teasing, pushing him toward poor decisions just to fit in. He deeply loves his son and hopes Lu will avoid making the same mistakes he did.

Known simply as "Coach," Otis leads the Defenders middle-school track team. He is a former Olympic runner who uses tough love and creative methods to teach his athletes how to succeed both on and off the track. Having grown up in a difficult environment with an addicted father and a working mother, he values hard work and personal accountability.

Christina is Lu's mother and the creative owner of Picasso of Produce, a custom fruit sculpture business. Her current pregnancy is considered a medical surprise, as doctors previously told her she could not have more children. She is highly perceptive and emotionally supportive, taking time to understand her family's fears.

Kelvin is a former classmate of Lu who used to brutally mock his albinism. He is large for his age and recently transferred schools to live with his grandfather due to difficulties at home. His past cruelty deeply impacted Lu's self-esteem and forced Lu to use defensive mantras.

Ghost is one of Lu's closest friends on the Defenders track team. He has a troubled family background involving an incarcerated father but finds stability and camaraderie through running. He is fiercely protective of his friends and firmly dislikes bullies of any kind.

Patty is a dedicated runner on the Defenders track team. She recently transferred to a private school and has a habit of bluntly speaking her mind. She enjoys playfully teasing her friends, especially regarding their crushes or social awkwardness.

Sunny is a member of the core friend group on the Defenders track team. He runs alongside Lu, Ghost, and Patty, providing reliable friendship and steady support during their practices and meets.

Aaron is the co-captain of the Defenders. He is competitive and resents having to share his leadership title with Lu. He frequently targets Lu's reliance on sunscreen and his flashy jewelry, creating friction on the team.

Coach Whit is the assistant coach for the Defenders track team. Outside of her responsibilities at practice, she desperately tries to help her brother break free from his substance use disorder, writing impassioned letters to encourage him to seek help.

Torrie, known locally as "the Wolf," is a former neighborhood track star whose promising career ended due to severe substance addiction. He now spends his time on the streets, while his sister attempts to get him into professional treatment.

Cotton is Patty's best friend. She is a quiet, understanding girl who offers Lu a peaceful presence when he feels overwhelmed by his family tensions and track anxieties.

Mr. Charles is an older, hard-of-hearing man who runs a local corner store. He has a close bond with Ghost, having protected him during a family crisis in the past, and receives a surprise fruit delivery as a token of gratitude.