Piper is a 12-year-old girl whose family has recently lost their home due to a cascade of financial hardships. Moving into an emergency shelter, she feels lonely and disconnected from her previous life. She is highly observant and empathetic, quickly forming a connection with a dog named Baby. Her desire for community leads her back to the Firefly Girls organization.

Baby is a small brown dog who lives on the streets with his owner, Jewel. He is deeply attuned to human emotions, able to sense sadness and actively working to comfort those around him. He considers Jewel his entire world and views the two of them as a pack of two. When separated from her, he shows immense loyalty and determination to reunite.

Jewel is a former music teacher currently experiencing homelessness while traveling. She relies heavily on her dog, Baby, for emotional support and companionship. She faces health challenges that cause severe confusion and memory loss when she runs out of medication. Despite her precarious physical condition, she steadfastly refuses to seek shelter if it means abandoning her dog.

Ree is a woman living in the park with her large dog, Ajax. She has dreadlocks and an eyebrow ring, which initially makes Piper wary of her. Having escaped an unsafe home environment, she harbors a general mistrust of humans and strongly prefers the company of animals. She is fiercely protective of her park community.

Gary is Piper's father, a man trying to keep his family afloat after losing his job and their home. He faces the immediate stress of being separated from his wife and children because the initial emergency shelter only houses women and children. He continually searches for employment and tries to maintain a positive outlook for his children.

Meg is Piper's mother, who struggles with the stress of the family's sudden descent into financial distress. She constantly reminds Piper to look at the positive side of things, encouraging her to focus on the doughnut rather than the hole. She actively pursues job interviews and attempts to maintain a sense of normalcy.

Dylan is Piper's younger brother. He struggles with asthma and the upheaval of moving into a shelter, occasionally showing his distress through regressions like bed-wetting. He relies heavily on his parents and sister for stability during their difficult transition.

Ajax is Ree's large dog and constant companion. He lives in the park with Ree, providing her with unconditional love and serving as her primary family member.

Gabriela is a young girl staying at the same emergency shelter as Piper. The two girls quickly strike up a friendship, providing each other with a brief sense of companionship before Gabriela's family abruptly moves out.

Karina is a member of the Firefly Girls who lives at Hope House and rides the bus with Piper. Having given up her own dog to move into the shelter, she immediately empathizes with Jewel and Baby's situation. She is proactive and helps organize efforts to assist them.

Sapphire is a Firefly Girl who lives at Hope House. She is perceptive and openly discusses her living situation, helping Piper understand the social dynamics at school. She provides crucial insight into medical challenges, drawing from her own experience caring for her mother.

Mrs. Bailey is the troop leader for the local Firefly Girls. She provides a structured, welcoming environment for the children at Hope House. She actively supports the girls' initiatives and offers practical help, such as driving them to appointments and managing their sales.

Noah is a boy living at the shelter under the care of his older brother. He is resourceful and street-smart, having previously spent nights riding the subway to stay safe. He helps Piper investigate a physical clue related to Jewel's past.

Bernadette is Jewel's sister, living in a senior facility in Boise, Idaho. She uses a wheelchair and relies on others for transportation. She represents Jewel's intended destination and ultimate connection to family.