Ari is an 11-year-old student who recently left her guardian's comfortable home to follow her older brother out onto the streets. She is highly intelligent and volunteers at a local Head Start preschool, where she feels valued and useful. She spends her free time cutting out catalog pictures to create elaborate families of "paper things," providing her with a sense of security and control. She desperately wants to gain admission to Carter Middle School but struggles to maintain her academic performance while secretly unhoused.

Gage is Ari's 19-year-old brother and her only surviving relative. After clashing repeatedly with their guardian, he decides to move out and takes Ari with him under the false pretense of having secured an apartment. He tries to provide for his sister but lacks the resources, employment, and maturity required to keep them safely housed. He expresses his guilt and feelings of inadequacy through defensive anger and frustration.

Janna is the legal guardian of Ari and Gage, having taken them in after the death of their mother, who was her friend. She provides a safe, structured home but struggles to communicate effectively with Gage, leading to frequent arguments. Her rigid enforcement of rules masks her genuine concern for the siblings' welfare.

Reggie is a military veteran living on the streets after a disability cost him his home. He maintains an incredibly optimistic outlook and folds intricate paper airplanes to give to children. He offers Ari and Gage practical help and shelter, sharing the few resources he has without hesitation or expectation of reward.

Sasha is Ari's longtime best friend who comes from a stable, privileged background. As Ari's living situation deteriorates, Sasha notices her friend's unwashed clothes and evasive behavior but responds with judgment rather than empathy. She is highly focused on social status and gaining entry into Carter Middle School.

Daniel is a student in the gifted class who notices Ari struggling and steps in to help her. He is outgoing, slightly mischievous, and encourages Ari to help him complete a year-end bucket list of fun, rebellious school activities. He offers Ari a supportive presence that does not demand explanations about her personal life.

Briggs is Gage's oldest friend, working at a local party store. He lives in a cramped studio apartment with a strict landlord but regularly allows Gage and Ari to sleep on his floor cushions. He tries to be friendly to Ari and offers whatever practical help he can manage for Gage.

Chloe is Gage's girlfriend. She lives in an apartment in a rough neighborhood with roommates. While she cares for Gage, she views his responsibility to Ari as an annoyance and frequently shows irritation when the siblings need to crash at her place.

Mr. O is Ari's English and social studies teacher. He takes a genuine interest in his students' work and encourages Ari's historical research into Louisa May Alcott. He facilitates classroom discussions that inspire the students to take action on school traditions.

Ms. Finch is the school computer teacher. Initially appearing strict when she reprimands Ari for doing outside homework in her lab, she later demonstrates quiet observation and generosity toward Ari's difficult circumstances.

Kristen is the wife of Gage's friend Perry. Though initially displeased by the unannounced arrival of houseguests, she softens toward Ari, offering her a comfortable cupola room to sleep in and packing her lunch for the next day.

Fran is a staff member at the local Head Start preschool program. She is warm and welcoming to Ari, appreciating the help she provides with the young children. She openly discusses her own financial challenges, such as needing a new bicycle for transportation.

West is a social worker employed at the Lighthouse youth shelter. He tries to keep track of Gage and Ari, occasionally bending the shelter's age rules to ensure they have a safe place to sleep for the night.