Isaac is a tall, muscular sixth grader and a talented basketball player at Mendez Middle School. He feels insecure about his poor academic performance, worrying that his failures cause his mother stress and contribute to his parents' separation. He relies on his athletic ability for confidence but desperately wants to improve his grades to fix his family dynamic. He is fiercely loyal to his friends and willing to sacrifice his own time to help them succeed.

Marco is a physically small, academically gifted sixth grader who excels in math and coding. He feels inadequate because his absent father values sports over academics. To win his father's approval, he decides to try out for the middle school basketball team despite lacking natural athletic ability. He struggles with anxiety and often misinterprets social cues, but his earnest dedication makes him a fast learner.

Vero is Isaac's hardworking, newly separated mother who owns and operates a local Mexican restaurant. She provides a warm, nurturing environment through her constant cooking, but she carries the heavy stress of single parenting. She pushes Isaac to take his academics seriously and often resents having to act as the sole disciplinarian in his life.

Manuel is Isaac's father, a jovial man who works as a contracting crew supervisor. He struggles with an alcohol addiction that has led to his separation from Vero. Despite his unreliability and lack of focus on his son's schoolwork, he deeply loves Isaac and acts as an affectionate, surrogate father figure to Marco.

Byron is an athletic eighth-grade student and the star player of the middle school basketball team. He is physically imposing, wearing frosted tips in his hair, and frequently targets smaller or younger students for harassment. His aggressive bullying makes him a primary obstacle for both Marco and Isaac.

Marco's mother is a loving parent who attempts to compensate for her ex-husband's emotional neglect. She provides steady emotional support and encouragement for Marco's interests. She holds resentment toward her ex-husband's behavior and frequently reminisces about the past.

Marco's absent father is a former high school star basketball player who prioritizes athletics over academics. He neglects Marco, failing to show up for scheduled visits, and instead focuses his attention on his new girlfriend and her athletic son. His disinterest deeply wounds Marco and drives the boy's sudden interest in basketball.

Mr. Chavez is the middle school physical education teacher and basketball coach. He maintains strict rules against bullying in his locker room and values student effort over pure athletic talent. He is an ethical authority figure who supports the boys' development.

Isaac's grandmother lives with him and his mother, providing a steady presence in the household. She offers Isaac wisdom regarding his family history, helping him understand the root of his father's personal struggles.

Dos Equis is a fellow basketball player who shares a first-period class with Isaac. He is friendly but sometimes insensitive, making remarks about Marco's friends that make Isaac uncomfortable.

Nick is a sixth grader and one of Isaac's friends from their elementary school basketball team. He stands up to Byron when the older boy bullies Marco and mistakenly believes Marco is a basketball prodigy.

Ryan is a sixth-grade basketball player and friend of Isaac. Along with Nick, he intervenes when Byron harasses Marco and enthusiastically encourages Marco to try out for the team.

Oscar is a polite, scholarly sixth grader who quickly befriends Marco on the first day of school. He shares Marco's deep interest in coding and the robotics club.

Jorge is an academically focused sixth grader who sits with Marco at lunch. He attempts to include Isaac in conversations about coding, though their interests differ greatly.

Orlando is a new sixth grader who joins Marco's academically inclined friend group. He is enthusiastic about robotics and helps provide a comfortable social environment for Marco.

Ms. Ornelas is the school nurse, having transferred from Isaac and Marco's elementary school. She is an attentive caregiver who monitors the boys' health and assists Marco through episodes of anxiety.

Mr. Slaughter is a middle school teacher who is unusually short, helping Marco feel more comfortable about his own size on his first day. He is funny, kind, and enthusiastic about his students' academic dedication.

Mrs. Carey is the school principal. She is an understanding administrator who inadvertently misinterprets Marco's anxious confession about skipping class, offering him leniency instead of punishment.

Angie is the romantic partner of Marco's father. She attends basketball events with him and is the mother of Sean, an athletic boy who commands much of Mr. Honeyman's attention.

Sean is the athletic son of Mr. Honeyman's girlfriend, Angie. His sports accomplishments frequently draw the praise and attention of Marco's father, sparking deep feelings of jealousy and inadequacy in Marco.

Luis is a sixth grader and a former basketball teammate of Isaac from elementary school. He is part of the athletic friend group that Isaac wishes to spend more time with during lunch.

Saul is one of Isaac's basketball-playing friends from fifth grade. He joins the other boys at tryouts for the middle school basketball team.

Dr. Osburn is the pediatrician Marco has seen his entire life. He provides medical care for Marco's sports injuries and reassures the anxious boy about his physical growth.

Mauricio is one of Marco's friends from elementary school. Because he is placed in regular classes rather than honors, he and Marco do not share a schedule.

Amanda is an elementary school friend of Marco. She is placed in standard classes rather than honors, meaning she cannot share a schedule with Marco in middle school.