As the novel’s deuteragonist, River provides a sensitive and often fragile counterpoint to his mother’s formidable strength. Defined early on by his “weak lungs” and a resulting timidity, he is a boy who learns to make himself small in a world that feels overwhelming. His physical vulnerability contrasts sharply with his extraordinary musical gift of perfect pitch, which shows a potential for transcendence from the social status he was born into. For River, music is initially an intuitive language and a source of comfort, a private world where he can feel competent and safe. His journey is one of learning to navigate the external world with the same confidence he feels at the piano, a process that forces him to confront deep-seated fears and forge an identity separate from his mother’s all-covering protection and ambition.

River’s artistic and personal development is shaped by his two contrasting piano teachers. Professor Li, his first mentor, is driven by an intense, self-serving ambition. He recognizes River’s talent but views it as a vehicle for his own glory, imposing a high-pressure regimen focused on competition and showmanship. This environment fosters River’s technical skill but also cements his stage fright, linking his music to fear and failure. In contrast, Phyllis, his guardian and teacher in Beijing, offers a holistic and nurturing mentorship. A former concert pianist herself, she rebuilds River’s technique from the ground up, teaching him that “[t]he piano is about life” (197). Under her guidance, River reconnects with music as a form of emotional expression rather than a high-stakes performance, allowing him to heal from past traumas and mature as an artist.

Losing his mother is the key event that forces River’s transition into a resilient young man. His initial survival in the Beijing Railway Station, aided by the janitor Guo Bing, marks his first steps toward independence. Living with Phyllis provides him with stability and privilege, but also a deep sense of dislocation and guilt. Quitting the piano is a complex act of grief, an attempt to sever his connection to the dream he shared with his mother and the pain of her absence. His eventual return to music is a sign of his maturation; he decides to enter the World Chopin Competition to create a beacon for his mother, a fire “big enough for Mama to see” (251). This transforms his musical ambition into an act of love and a call for connection, completing his journey from a boy who used music to hide to a man who uses it to be found.

Though his physical presence in the novel is brief, Song’s husband Blue is a foundational and lasting moral center for the family. A static character, his gentle and quietly resolute nature acts as an important foil to Song’s more combative instincts. Where Song is prepared to fight the world, Blue’s strength lies in his peaceful resolve and optimism, exemplified by his advice to Song during the pineapple cart incident: “You don’t have to fight” (26). He is the architect of the family’s central dream of being “one family in one place” (23), a vision of stability and togetherness that fuels Song’s quest long after his death. 

Blue’s most lasting legacy is the pair of clothespin dolls, which function as powerful symbols of their familial bond. These dolls become talismans for Song and River, tangible reminders of Blue’s love and the connection that persists through separation and tragedy, making his influence felt throughout the narrative.

Professor Li is a complex figure who functions as both a mentor and an antagonist in River’s development. As River’s first piano teacher in Harbin, he is the one who initially recognizes and names his extraordinary talent, calling him a “little wonder.” His passion for music is genuine, and his teaching provides River with the technical foundation for his future success. However, Professor Li’s mentorship is tainted by his immense personal ambition and volatility. He views River as his instrument for achieving vicarious glory in the competitive classical music world. This self-interest ultimately proves destructive when, desperate for River to win the Harbin competition, he gives the boy beta-blockers without his mother’s consent, triggering a severe asthma attack. This act reveals the toxicity of his ambition and is the catalyst for Song and River’s move to Beijing, forcing them to seek a new, healthier path for River’s talent.

Phyllis enters the narrative as a classic mentor figure, providing River with a safe harbor and a new path forward after he is lost in Beijing. As a reclusive former concert pianist, she possesses the artistic authority and wisdom to guide River’s musical development. She becomes his legal guardian, offering him a life of stability and privilege that stands in stark contrast to the precarity of his childhood. Her teaching philosophy is the antithesis of Professor Li’s; she rejects the high-pressure world of competition and focuses on rebuilding River’s technique from its foundations, stressing musicality and emotional honesty over pure showmanship. By teaching him that music is about life, she helps him heal his relationship with the piano and with himself. She is a source of unwavering, patient support, facilitating River’s eventual decision to return to the stage on his own terms.

One of Phyllis’s defining characteristics is the privilege she extends to River once she assumes the role of his guardian. Though this privilege insulates River from the working-class world that Song inhabits, it ensures his safety from the harmful environmental conditions that would exacerbate River’s chronic asthma. Likewise, Phyllis’s privilege gives River the opportunities to access platforms like the World Chopin Competition, utilizing the connections River wouldn’t have had on his own. This contrast between Phyllis and Song underscores the systemic inequalities that mark the hukou system.

A fellow food delivery worker in Beijing, White Dragon is a key supporting character and a foil to Song. While he shares her life of precarious labor, his personality is her opposite: He is boisterous, outwardly cheerful, and approaches the dangers of their job with a reckless, almost fatalistic glee. His wild laughter and cavalier attitude provide a necessary release from the grim determination that consumes Song. 

White Dragon is the one who introduces her to the community of the courtyard house, breaking her long-standing isolation. Over time, he becomes her loyal friend and, eventually, her partner, offering her a source of personal comfort and emotional support. He represents the possibility of finding joy and connection even in the most difficult of circumstances, reminding Song that she does not have to bear her burdens entirely alone.

Mini, who calls herself “the Bachist,” is River’s first true friend and eventual girlfriend. Initially appearing as a privileged and somewhat arrogant rival at the Harbin competition, she quickly reveals a sharp wit and an underlying empathy. As a fellow young pianist navigating the intense pressures of the classical music world, she understands River in a way no one else can. She provides him with an important link to a normal teenage life, filled with movies, jokes, and games. Her confidence and unwavering belief in him are instrumental in pulling River out of the deep isolation he falls into after quitting the piano. It is her challenge that ultimately sparks River’s decision to return to the instrument for the purpose of creating a “fire” to call his mother home.