Annie is a twelve-year-old girl who loves running for the sheer physical sensation of it rather than for competition. She processes the changing world around her—including her mother's pregnancy and her grandfather's mental decline—through drawing and physical movement. She struggles to understand the motivations of adults and peers who want to turn her natural passions into structured sports.

Max is Annie's thirteen-year-old childhood friend and frequent running partner. Following the departure of his father, he has grown quiet and prone to shifts in mood, creating a distance between him and Annie. He views competitive running and winning as his ticket out of their small town, desperately wanting to join the school track team.

Annie's Mother is expecting a new baby and managing the physical and emotional changes of her pregnancy. She approaches the upcoming birth with confidence, preferring a birthing center over a hospital. She also manages the emotional toll of watching her own father suffer from memory loss while trying to maintain a positive outlook for her family.

Annie's Grandfather is an elderly man living with his daughter's family. He frequently suffers from memory loss and confusion, occasionally forgetting his own past or how to perform familiar tasks like cooking fried chicken. A former champion racer who quit competitive running at age fifteen, he understands Annie's desire to run simply for the joy of it.

Annie's Father helps his family prepare for the arrival of a new baby. He shares moments of humor with Annie regarding ultrasound images but harbors quiet anxiety about the birthing process. He attends birthing center visits and steps into a supportive role alongside his daughter to brace for the upcoming life changes.

Baby Joey is the unborn child growing inside Annie's Mother. His impending arrival serves as a catalyst for Annie's questions about fetal development, life cycles, and how a tiny cluster of cells eventually becomes a whole person with memories and an identity.

Mr. Welling is a school teacher who challenges his students to expand their thinking and vocabulary. He bans common filler words like 'um' and 'stuff' from his classroom and encourages the use of a thesaurus, directly impacting how Annie narrates her own thoughts.

Miss Freely is Annie's art teacher. She initiates a long-term drawing project that helps her students observe the passage of time and discover their own unique artistic lines and perspectives.

Ms. Cobber is an elderly neighbor who pays Annie to perform light chores around her house. This arrangement allows Annie to save money for art supplies rather than track shoes.

The school's track coach is a persistent school figure who repeatedly pressures Annie to run competitively. She interprets Annie's refusal as fear rather than a genuine preference for solitary running, causing significant friction.

Kaylee is a school friend of Annie's. She serves as a sounding board for middle-school social dynamics, specifically asking Annie about her potential romantic interest in Max.