Rose is an eleven-year-old fifth-grader living in Hatford, New York, who has high-functioning autism. She relies heavily on daily routines and strict adherence to rules to make sense of her world. Her environment often overwhelms her with sensory input, making mainstream classroom learning difficult. She finds stability in her dog, Rain, and the presence of her uncle.

Wesley is Rose's father and a single parent raising her in Hatford. He works intermittently at a local garage and spends significant portions of his free time drinking. Having grown up in an abusive household and the foster care system, he insists on keeping Rose in her current school despite recommendations for specialized care. He frequently exhibits impatience and a lack of understanding regarding Rose's daily needs.

Weldon is Wesley's brother and Rose's uncle, also residing in Hatford. He spends considerable time with Rose, driving her to and from school and engaging in her homonym games. Unlike his brother, Weldon makes a concerted effort to understand Rose's perspective. He actively participates in her daily life and helps her manage unexpected disruptions.

Rain is a small yellow Labrador mix that Wesley finds without a collar behind a local bar. As Rose's pet, the dog provides essential emotional grounding and uncritical companionship. Rain intuitively connects with Rose, learning to travel through the school environment by scent.

Mrs. Leibler is an aide at Hatford Elementary assigned to support Rose throughout her school day. She helps Rose manage sensory overload by removing her from loud environments when necessary. She also organizes rotating lunch buddies to help Rose practice conversational skills with her peers.

Mrs. Kushel is Rose's fifth-grade teacher at Hatford Elementary. She manages a classroom that includes students dealing with the aftermath of a major storm. She acts as a supportive educational figure for Rose, offering practical advice and connecting her with a local journalist for a personal project.

Parvani is a fifth-grade student in Rose's class at Hatford Elementary. She initially interacts with Rose in a standard classroom setting but gradually establishes a stronger connection. She distinguishes herself from other classmates by actively participating in Rose's homonym game.

Anders is a student at Hatford Elementary and one of the classmates assigned to eat lunch with Rose. He occasionally struggles to follow the strict classroom rules that Rose values, inadvertently causing friction. His family faces significant upheaval due to severe storm flooding.

Flo is another fifth-grade classmate of Rose at Hatford Elementary. She participates in the school's effort to integrate Rose socially by serving as a lunch partner. Though initially stiff during their scripted conversations, she eventually warms up when discussing class assignments.