Jessie is Isa's twin sister, characterized by her scientific curiosity and practical mindset. She navigates her unique interests and relationship with Isa, illustrating the diverse paths of teenage development.

Hyacinth is a gentle, introverted child with a love for crafts and creativity. She gradually finds her courage and learns the true meaning of bravery in her interactions with her family and community.

Oliver is a spirited young boy who loves the thrill of adventure. Throughout the story, he learns the importance of kindness and generosity towards others.

Papa is the warm-hearted and optimistic father of the Vanderbeeker children, working hard to provide for his family while maintaining a positive outlook. He embodies a nurturing presence in their lives.

Mama runs a business from home and is the primary caregiver, balancing realism with hope as she leads her family through challenging circumstances. She demonstrates strength and dedication to her home and family.

Mr. Beiderman is the children’s mysterious and reclusive landlord who initially presents as an antagonist. His character evolution reveals depth and complexity as the story unfolds.