Theo is a widowed astrobiologist who builds computer models predicting the atmospheres of distant, undiscovered planets. Following the sudden death of his wife two years prior, he operates as a highly anxious single father trying to raise his neurodivergent son in a rapidly destabilizing society. He refuses to put his child on psychoactive medications, preferring to manage behavioral outbursts with patience, nature retreats, and stories about imaginary alien worlds.

Robin is a nine-year-old boy diagnosed with Asperger syndrome, obsessive-compulsive disorder, and attention deficit hyperactivity disorder. He possesses an overwhelming, raw empathy for endangered animals and the natural environment. To process his grief over his mother's death and his frustration with apathetic humans, he paints watercolors of threatened species and plans elaborate charity projects.

Alyssa is a deceased animal rights lawyer and lobbyist who died in a car collision two years before the events of the narrative. Even in death, she serves as the moral center of the family. She was fiercely dedicated to protecting nature and established a legacy of environmentalism that her son now attempts to carry forward.

Martin is a confident, ambitious neuroscientist who pioneers an experimental neurofeedback treatment. He operates a university lab where he teaches patients to regulate their emotional states using visual feedback. He sees an opportunity to help Robin manage his angry outbursts, though his past friendship with Alyssa creates unspoken tension in the laboratory.

Jinjing is a graduate student working in the astrobiology department. She is kind and accommodating, frequently stepping in to supervise Robin and show him science exhibits when his father is overwhelmed by professional duties.

Carl is an expert in astrochemistry who partners with Theo to predict atmospheres on distant planets. He is highly focused on academic competition and shows little patience for the frequent scheduling disruptions caused by his partner's parenting duties.

Dr. Lipman is the school psychiatrist handling behavioral issues. She strictly emphasizes the need for social integration and places formal pressure on parents to consider psychoactive medications or behavioral interventions when a child struggles in the classroom.

Jayden is a classmate and the only real friend of the protagonist's son. The boys suffer a falling out when Jayden makes an insensitive, speculative comment regarding the circumstances of a fatal car crash.

Inga is an autistic teenage activist leading a massive environmental movement across Europe. She serves as a distant, digital role model, demonstrating how a neurodivergent person can mobilize society and make a tangible impact on ecological policies.

Dee is a producer for an internet television channel who tracks down the anonymous subject of a successful university study. She is opportunistic and determined to create viral video content, brushing past parental reservations to secure her interviews.