Cat is an 11-year-old girl who serves as the primary caretaker for her younger brother. Following the death of her father, she acts as the practical anchor for her family, preparing meals and anticipating problems so her mother can work undisturbed. While highly capable and fiercely protective, she feels the heavy weight of this responsibility and desires the space to pursue her own interests.

Chicken is a young boy with special needs who requires strict routines and calm environments to feel secure. He possesses a vivid imagination and an encyclopedic knowledge of sharks. Deeply reliant on his older sister for emotional regulation, his summer on Gingerbread Island slowly pushes him to develop confidence and handle discomfort on his own.

Amanda is a hardworking children's book author, illustrator, and teacher who creates popular stories based on her own children. Widowed and facing lingering financial pressure, she immerses herself in her career to provide for her family. This intense focus causes her to unintentionally place too much caretaking responsibility on her young daughter.

Macon is a retired surgeon living on Gingerbread Island who initially struggles to interact with the grandchildren he has never met. A disciplined man who prioritizes hard work and nature conservation, he hides deep regrets about his past parenting mistakes behind a quiet exterior. He gradually reveals his supportive nature by teaching Cat how to fish.

John Harvey is a 12-year-old local boy whose family owns the island's miniature golf course. As a four-time winner of the local kids' fishing tournament, he is fiercely competitive and openly hostile toward summer visitors. Despite his regular bullying and taunts, he occasionally acts with surprising empathy.

Lily is Amanda's mother and a year-round resident of Gingerbread Island. Unlike her husband, she is immediately warm, perceptive, and eager to build relationships with her grandchildren. She provides a nurturing presence in the home, gently stepping in to handle Chicken's routines so Cat can experience a normal summer break.

Harriet is a local girl on Gingerbread Island who quickly befriends Cat. She is adventurous, familiar with the island's rhythms, and provides Cat with a low-pressure friendship. She actively encourages Cat's entry into the fishing tournament and joins her for bike rides and miniature golf.

Rishi is Cat's best friend who recently moved from San Francisco to Atlanta. Though he spends the summer in India due to a family emergency, he remains a vital tether to Cat's everyday life. He maintains contact through emails and video calls to share updates on their drastically different summer experiences.

Neddie is Harriet's younger brother. He is an active, typical boy who participates in local summer activities and occasionally clashes with other children, though he quickly moves past minor disagreements.

Walt is Harriet and Neddie's older brother. He is a local teenager who observes the younger kids' activities and provides casual commentary on the dynamics of the local fishing contest.

Dean is the knowledgeable owner of the island's bait shop. Remembering Amanda from her youth, he is friendly and encouraging toward Cat, offering her free bait and basic advice to help her get started in the tournament.

Manjula is Rishi's mother and a close family friend to the Gladwells. Her sudden departure to India to care for her mother after a stroke serves as the catalyst for Cat and Chicken's unexpected trip to Gingerbread Island.