Darius is a fifteen-year-old high school sophomore living in Portland, Oregon. He is of Iranian descent on his mother's side and European descent on his father's side, which often causes him to feel inadequate regarding his cultural heritage. He takes medication for clinical depression and experiences intense social isolation at school, where his weight and ethnicity make him a frequent target for bullying. Despite his insecurities, he possesses a rich inner life fueled by science fiction, fantasy, and a deep appreciation for tea.

Sohrab is an Iranian teenager who lives next door to the Bahrami family in Yazd. As a member of the Bahá'í faith, he belongs to a persecuted religious minority, making him a social outsider among his peers. He is a lean, athletic soccer player who freely displays physical affection and emotional openness. He frequently runs errands and does yard work for Darius's grandparents, seamlessly fitting into their daily routines.

Stephen is an architect of European descent living in Portland. He has blond hair, blue eyes, and an outward demeanor of strict discipline that Darius likens to a Teutonic superman. He manages his own clinical depression and tries to prevent Darius from experiencing the same depths of illness, though his methods often manifest as harsh criticism regarding his son's diet and behavior. He shares a nightly tradition of watching Star Trek episodes with his family.

Shirin is an Iranian immigrant who works as a UX designer in Portland. She left her home country to marry Stephen and has not returned to Iran since before the birth of her children. She acts as the emotional center of the Kellner household, frequently intervening when Stephen's strictness hurts Darius's feelings. She intentionally raised Darius with mostly American customs to spare him the alienation she felt as an immigrant.

Laleh is Darius's younger sister, currently in the second grade. Unlike her brother, she is fully bilingual in English and Farsi, which allows her to adapt to social situations effortlessly both in America and in Iran. She possesses a bubbly, outgoing personality that naturally draws people's attention, making her much more popular than Darius at school.

Ardeshir is Darius's grandfather, an older Zoroastrian man living in Yazd. He faces a terminal brain tumor diagnosis that causes memory loss and unpredictable mood swings. He holds traditional views regarding mental health and worries deeply about his cultural legacy fading as his family assimilates into American life. He relies on his neighbors for assistance as his health slowly declines.

Fariba is Darius's grandmother, a deeply welcoming presence in Yazd who manages her household with warmth and hospitality. She wears peach-scented perfume and pomegranate-red nail polish, frequently offering traditional Persian food to comfort her family. She handles the emotional and physical strain of her husband's declining health with quiet resilience.

Trent is a high school sophomore and junior varsity athlete at Chapel Hill High. He uses his popularity to target students he perceives as vulnerable, frequently focusing his attention on Darius. He employs homophobic slurs and racist stereotypes to assert dominance in his social circle.

Cyprian is a varsity wrestler at Chapel Hill High who participates in bullying alongside his friend Trent. He possesses conventional good looks and significant athletic talent. He occasionally shows signs of guilt regarding his treatment of Darius, attempting clumsy apologies when Trent is not present.

Charles is the manager at Tea Haven in Portland where Darius works. He follows corporate scripts rigidly and lacks awareness of the social dynamics between his employees and customers. Despite his professional detachment, he grants Darius time off for his trip, noting the importance of connecting with one's roots.

Javaneh is a Persian American student at Chapel Hill High. She serves as Darius's closest peer connection at school, though their bond relies mostly on their shared heritage rather than deep emotional intimacy. She possesses the olive-toned complexion that Darius envies.

Jamsheed is Shirin's brother who lives in Iran. He strictly follows traditional Iranian codes of politeness, known as taarof, which confuses Darius when they meet in person. He actively participates in family gatherings, feast preparations, and card games.

Soheil is one of Darius's uncles living in Iran. He frequently engages in physical greetings, such as patting stomachs, which makes Darius self-conscious. He actively participates in the men's social activities during large family events.

Simin is Soheil's wife and Darius's aunt by marriage. She speaks very little English but shows immense curiosity about Darius's life in America, relying on Sohrab to translate so she can connect with her nephew.

Ali-Reza is an Iranian teenager who plays soccer in the same park as Sohrab. He holds strong prejudices against the Bahá'í faith, leading to frequent tension and arguments on the field. He also participates in group mockery when he notices Darius's physical differences in the public showers.

Hossein is a local teenager who frequents the soccer fields in Yazd. He teams up with Ali-Reza against Sohrab and Darius, participating in the casual but intense athletic rivalries of the neighborhood.

Mahvash is Sohrab's mother, who lives next door to the Bahrami family. She faces significant emotional and social burdens due to her family's persecution and her husband's imprisonment. Despite her difficulties, she maintains a warm household and frequently shares food with her neighbors.

Parviz is one of Darius's cousins in Iran. He listens eagerly to Sohrab's exaggerated tales of Darius's athletic prowess and takes the time to teach Darius how to play the traditional card game Rook.

Navid is another of Darius's cousins who lives in Yazd. He participates in the younger generation's activities during family parties, ensuring Darius is included in their games.

Coach Fortes is the gym teacher at Chapel Hill High School in Portland. He recognizes Darius's improved athletic skills and actively encourages him to participate more fully in school sports.