A boy who becomes friends with Delsie and shares a similar experience of being abandoned by his mother. He is initially misunderstood by others but is shown to be kind and brave.

Delsie's grandmother, who raised her after her mother left. She is a strong-willed woman coming to terms with personal losses while providing love and support to Delsie.

Delsie's next-door neighbors, consisting of Henry, Esme, and their daughter Ruby, who care for Delsie like family members, offering her love and guidance.

Delsie's grumpy neighbor who initially seems harsh but gradually reveals her grief and emotional complexity, showing she is misunderstood rather than unkind.

A seasonal visitor to Cape Cod and a friend of Delsie, who undergoes changes and shifts her interests, impacting her friendship with Delsie.

The primary antagonist and bully, who looks down on Delsie and often acts cruelly, yet shows hints of more complex emotions.

Ronan's father, who initially appears distant but is revealed to be a caring, if gruff, parent as he adjusts to life with his son.

School friends of Delsie who appear in a summer play and represent true friendship by standing up for her against bullies.

Owner of a local restaurant known for her gruff demeanor and tendency to encourage customers to participate in their own meal preparation.

Delsie's mother, whose absence profoundly influences Delsie's life. Her struggles with addiction are recounted through stories, impacting the experiences of both Delsie and Grammy.