Gregory is a nine-year-old boy who uses drawing and painting to cope with his difficult surroundings. After his father loses his factory job, Gregory is forced to move to a small house in a neighborhood filled with concrete and businesses, causing him to leave his old school behind. He carries his tablet, paints, and brushes everywhere he goes. He relies on his optimistic attitude and independent nature to find a quiet space of his own in a burned-out chalk factory behind his yard.

Gregory's mother works as a cook in a restaurant and is under significant financial pressure following her husband's job loss. She tries to provide for Gregory, converting a small porch into a bedroom for him, but her exhaustion often limits her ability to engage with his artistic interests. She means well but frequently offers generic reassurance rather than actively helping Gregory solve his problems at school.

Gregory's father recently lost his job as a factory worker and has taken a new position as a security guard. His job loss is the catalyst for the family's move to a smaller house in an industrial neighborhood. He has a jovial personality and supports Gregory's desire to play outside, though his work schedule keeps him largely absent from Gregory's daily routine.

Vance is a large boy in Miss Perry's class who functions as the ringleader among the students at the Dover Street School. He takes offense easily and is highly insecure about his environment. When Gregory casually mentions the size of his previous school, Vance immediately accuses him of bragging and lying, establishing an environment of exclusion.

Uncle Max is a twenty-year-old relative with a red beard who moves into the family's house because he is unemployed. He takes over Gregory's bedroom space, spending his days sleeping, watching television, and playing the guitar. He is insensitive to boundaries, regularly mocking Gregory by calling him "the Paintbrush Kid" and covering up Gregory's paintings with his own car posters.

Miss Perry is the classroom teacher at the Dover Street School. She attempts to make Gregory feel welcome by asking him to share details about his previous school, unaware that this will cause friction with the other students. She pays attention to her students' individual interests and brings guests into the classroom to enrich their learning.

Ivy is a shy, small girl with long dark hair in Gregory's class. She speaks very quietly, relying on her artwork as her primary method of communication. She takes art very seriously and possesses a fair-minded attitude, carefully observing the interactions in the classroom even when she does not participate in them verbally.

Miss Cartwright is the art teacher who instructs Gregory and his peers a few hours a week. She strongly values artistic expression and organizes formal recognition for students who excel in art, demonstrating to the entire school that creativity is a celebrated skill.

Mr. Hiller is the owner of a local plant nursery. He visits the Dover Street School at Miss Perry's invitation, using his own chalk drawings on the board to teach the children about various vegetables and flowers. He provides the students with plant cuttings so they can start gardens of their own.

Aunt Grace is Gregory's aunt who watches him on his ninth birthday while his parents move the family's belongings into their new house. She provides him with a place to stay during the hectic transition.