Muiriel is a seventeen-year-old high school senior who has spent her entire life in the foster care system. Born with a prenatal meth addiction, she maintains a perfect academic and behavioral record to ensure she can change homes whenever she feels too comfortable. She actively avoids forming attachments and focuses entirely on aging out of the system in one year so she can live independently. Her love for nature and the writings of John Muir heavily influence her daily life and career aspirations.

Francine is a woman in her sixties who lives on a Puget Sound island and serves as Muiriel's final foster parent. A former pediatric nurse, she turned to foster parenting after a divorce. She runs a quiet, orderly household and communicates with straightforward, refreshing honesty rather than excessive sentimentality.

Kira is a Japanese American twelfth grader who relocated from Los Angeles to the island a year ago. She is a gifted painter and baker who designs her own elaborate tattoos. Despite her artistic talents, she avoids art classes due to persistent bullying from popular students.

Sean is a popular, handsome high school senior who works alongside Muiriel at Salishwood. He hopes to study environmental science and become a park ranger like his parents. After losing his father at a young age, he spent a year hiking the Sierra Nevada with his mother to find peace in nature.

Zola is a ten-year-old girl in the foster care system who briefly shares a home with Muiriel. She experiences significant anxiety about her placements and relies on her older foster sister for comfort and reassurance. Her braided and beaded hair reflects her personal style, and she values small objects that represent connection.

Joellen is a dedicated social worker who has handled Muiriel's case since childhood. She advocates for her clients and tries to place them in environments where they can succeed. She affectionately calls Muiriel "Blackbird" and encourages her to finish high school in one place.

Jane is the gray-haired director of the Salishwood Environmental Education Center. She is enthusiastic about hiring qualified staff to teach elementary school groups about wilderness ethics. She struggles to manage difficult employees due to complicated family ties and financial obligations.

Natan is a thirty-two-year-old employee at the Salishwood Environmental Education Center who sports a mustache and a man-bun. He frequently shares misinformation with students and demonstrates inappropriate behavior toward his teenage coworkers. He uses his family connection to the director to maintain his position despite complaints.

Terry Johnson is Francine's senior dog. He spends his days resting in the quiet house and occasionally curling up with Muiriel when she sleeps on the living room couch. He provides silent comfort and a sense of unconditional acceptance to the household.

Tiana is a popular twelfth-grade student on the island. She actively torments Kira, utilizing verbal cruelty and the destruction of property to maintain social dominance. She aggressively guards the attention of male classmates and creates hostile environments for anyone who challenges her authority.

Katrina is a popular high school senior who acts as Tiana's primary associate. She participates in the ongoing harassment of Kira and relies on Sean for academic tutoring.

Elliot is a high school art student with an interest in photography. He appreciates Kira's artistic talent and frequently attempts to spend time with her despite interference from other students.

Mrs. Aoyama is Kira's mother. She relocated her family from Los Angeles to the island to help Kira break away from self-destructive habits. She maintains a warm, decorated home and considers those who help her daughter to be part of the extended family.

Sarah is Sean's mother and a professional park ranger stationed at Mount Rainier. She shares her son's passion for the outdoors and actively supports his educational and romantic interests. After her husband's death, she took Sean on an extended hiking trip to help them process their grief.