Lafayette is a quiet, contemplative 12-year-old boy living in a New York City borough. Since the unexpected death of his mother, he has grown increasingly antisocial, preferring to stay in his family's apartment rather than play with friends. He struggles with guilt over his mother's passing, frequently imagining conversations with her to process his profound grief.

Charlie is the 15-year-old middle Bailey brother who recently returned from a two-year sentence at Rahway Home for Boys for attempting to rob a candy store. Adopting an attitude of toughness and defensiveness, he is dubbed "Newcharlie" by Lafayette. He projects anger and frequently directs cruel remarks at his younger brother, masking deep-seated frustration regarding his inability to prevent their mother's death.

Ty'ree is the 21-year-old oldest Bailey brother and the legal guardian of Lafayette and Charlie. Often referred to by neighbors as "Saint Ty'ree" for his selflessness, he abandoned his plans to attend MIT to work full-time and keep his brothers out of the foster system. He manages the family's tight finances carefully and attempts to project an upbeat attitude, quietly mourning the loss of his parents in private.

Milagros is the deceased mother of the three Bailey brothers who immigrated to New York from Puerto Rico. She raised her sons with strong values and strict expectations, insisting they learn English and refusing outside charity. Her sudden death from insulin shock a year prior to the story's start serves as the central trauma affecting all three boys.

Aaron is a local teenager who admires Charlie's newfound street credibility following his time at the juvenile detention center. Eager to project his own toughness, Aaron attempts to establish himself within the neighborhood's gang hierarchy. He frequently pressures Charlie into risky situations to boost his own status among local troublemakers.

Aunt Cecile is the boys' great-aunt who travels from the South following Milagros's death. She originally intends to take Lafayette and Charlie to live with her, offering them a stable environment away from the city. She represents a constant alternative living arrangement should Ty'ree fail to meet his guardianship responsibilities.

The late patriarch of the Bailey family, who died of hypothermia after rescuing a jogger and her dog from a frozen pond in Central Park. Because his death occurred while Milagros was pregnant with Lafayette, the youngest brother only knows him through stories. His tragic heroism casts a long shadow over his sons.

Dr. Vernon is a psychologist based in Harlem whom Aunt Cecile hired to help Lafayette process his grief. He uses a gentle, kind approach to encourage the initially reluctant Lafayette to speak openly about his feelings of guilt and sorrow.

Smitty is a neighborhood peer and friend of Lafayette. He regularly tries to include Lafayette in typical adolescent activities, serving as a vital connection to the outside world during Lafayette's period of isolation.

PJ is another boy from the neighborhood who plays basketball with Smitty and Lafayette. He represents the casual social circle Lafayette has withdrawn from following his mother's sudden death.