William, affectionately known as "Scoob," is an 11-year-old Black boy who feels misunderstood by his strict father. After getting into trouble at school for defending a friend, he jumps at the chance to skip town. He is observant and sensitive, struggling with the pressure to be perfect while learning about the historical realities of race in the American South.

Ruby Jean is Scoob's energetic, white grandmother who initiates a cross-country road trip. She is fiercely protective of her grandson and carries a treasure box of mementos from her past. Her journey is driven by a desire to retrace a route she originally attempted in the 1960s with her husband, relying on an old edition of the Green Book to guide them.

James is Scoob's father, a man who holds his son to exceptionally high standards. He is deeply concerned about how society treats Black boys and uses rigid discipline to protect Scoob from potential trouble. This heavy-handed approach creates a communication barrier, leaving him unaware of the true motivations behind his son's actions.

Jimmy is Scoob's late grandfather, a Black man who traveled the segregated South with his white wife in the 1960s. The family rarely speaks of him due to a criminal past that ended in his imprisonment. He remains a heavy presence in the family's memory, particularly for G'ma as she retraces their old travel route.

Shenice is Scoob's good friend from home. They have a long history of looking out for each other. Scoob's protective instincts regarding her younger brother directly contribute to his current disciplinary troubles.

Bryce is a white classmate of Scoob who targets a younger, vulnerable student. His persistent bullying behavior pushes Scoob to react physically, setting the novel's main events in motion.

Drake is Shenice's younger brother who has epilepsy. His vulnerability makes him a target for classroom bullies, prompting Scoob to step in and defend him during a seizure.