Leigh is a high school sophomore and visual artist dealing with her mother's recent suicide. She is of mixed Taiwanese and Irish American heritage, which often makes her feel isolated or stereotyped by others. As an artist, she perceives emotions in vivid colors and uses charcoal and paints to process her complex world. Leigh travels to Taipei to search for her mother, whom she firmly believes has taken the form of a large red bird.

Dory is a talented pianist from Taiwan who changed her name from Dorothy upon moving to the United States. She possesses a quirky personality and a habit of mixing up English idioms, but she suffers from severe, lifelong depression. She completely severed ties with her parents when she married Brian, keeping her past a secret from her daughter. Following her death, she appears to Leigh as a striking red bird.

Brian is an Irish American sinologist who travels frequently to Asia for his academic career. He teaches Leigh limited Mandarin and acts as a buffer between her and the maternal family she has never met. Unable to cope with his wife's deteriorating mental state, he often retreats into his work, creating a physical and emotional distance from his daughter. He brings Leigh to Taipei but struggles to remain in the environment that reminds him of his wife.

Yuanyang, known to Leigh as Waipo, is a petite Taiwanese woman with a strong will and a complex personal history. She was born into a poor family and adopted out as a child, only to eventually reunite with her biological relatives and marry on her own terms. Despite her traditional values and initial hostility toward Dory's marriage, she is deeply affectionate toward her newly discovered granddaughter. She helps guide Leigh through Taipei's temples and cultural practices.

Axel is Leigh’s best friend, sharing her experience of being a mixed-race student in their school district. Half Puerto Rican and half Filipino, he understands the feeling of straddling different cultures. He is an introverted musician who associates emotions with specific colors, frequently checking in on Leigh by asking what color she feels. His mother abandoned his family when he was young, leading him to view Dory as a maternal substitute.

Jingling is Dory’s older sister, raised in Taiwan alongside her. Unlike her rebellious younger sibling, she embodies obedience and responsibility, striving to fulfill her parents' expectations. She possesses a deep fondness for the poetry of Emily Dickinson and floral dresses. Her life in Taiwan leaves a lasting impact on her parents and shapes the family dynamics that Dory eventually flees.

Leigh’s maternal grandfather is a quiet, steady presence in the Taipei household. He spends his days going to the local park, observing nature, and playing games. While he originally opposed Dory's marriage to an American, he welcomes Leigh into his home with gentle acceptance. He provides Leigh with moments of peace during her frantic search for the red bird.

Caro is a supportive classmate who befriends Leigh during her freshman year. She provides Leigh with an escape from her tense home environment, offering a welcoming household and a listening ear. Caro is perceptive about the complicated dynamic between Leigh and Axel, occasionally trying to set them up or force them to communicate.

Leanne is a high school student and band member who dates Axel on and off. Her presence is a constant source of insecurity for Leigh, who views Leanne as a barrier to her own romantic relationship with Axel. Leanne is highly protective of her status as Axel's girlfriend and reacts strongly to his closeness with Leigh.

Dr. O'Brien is Leigh’s mental health professional. He attempts to help Leigh process the trauma of her mother's suicide through clinical, psychological frameworks. He attributes Leigh's visions of the red bird to a manifestation of intense grief, representing the logical, Western approach to her experiences.

Mel is Caro’s mother. She offers Leigh a glimpse into a functional, open family dynamic that contrasts sharply with the secretive environment of the Sanders household. She assists Leigh when Dory is found incapacitated on the kitchen floor.

Gaelle is Caro’s maternal grandmother. Her openness and curiosity about Leigh's family prompt Leigh to recount the story of her parents' courtship. Gaelle's presence highlights Leigh's lack of connection with her own maternal grandparents.

Cheslin is Caro’s girlfriend. She is comfortable in her own skin and uninhibited, contrasting with the tense, awkward dynamic between Leigh and Axel. Her presence during social outings highlights the difference between established relationships and unspoken feelings.

Dr. Nagori is Leigh’s high school art teacher. She recognizes Leigh's technical skill but pushes her to inject more genuine emotion into her work. She selects Leigh to submit a portfolio to an international art show for emerging artists in Berlin.

Weston is a classmate from Leigh’s art class who attends the winter formal. He views Leigh's mixed-race heritage as exotic and kisses her at the dance. His actions force Axel to confront his own jealousy regarding Leigh.

Fred is a grumpy, middle-aged, English-speaking man who resides in Jiufen. He participates in traditional Taiwanese spiritual practices and is deeply attuned to the presence of ghosts, particularly during Ghost Month. He possesses a birthmark that he believes destined him for a unique spiritual path.