Olly is Madeline’s energetic and physically active new neighbor who wears black and is interested in math. He has a turbulent family life but forms a meaningful connection with Madeline.

Pauline is Madeline’s overprotective mother and primary medical caregiver. She is a structured, punctual person deeply committed to her daughter's well-being.

Carla is the compassionate nurse who has cared for Madeline for most of her life. Although she helps facilitate Madeline’s relationship with Olly, she also cautions her about the potential consequences.

Mr. Bright is Olly’s father, who struggles with alcohol dependency and has an abusive relationship with his family. His actions contribute to the difficulties faced by Olly and his family.