A fictionalized version of the historical financier and industrialist, J.P. Morgan (1837-1913), who hires Belle. In the novel, he is portrayed as a powerful, wealthy man who thrives on domination. His hiring of Belle defies convention, reflecting how he uses his influence, but his relationship with her becomes strained due to his professional and personal boundary violations.

Belle's mother, beautiful and white-presenting, based on the historical Genevieve Ida Fleet Greener (1849-1941). She compels her children to pass as white as a strategy for survival in the face of racism. Her ambition and strictness create conflict with Belle but show her commitment to securing her family’s future.

Based on the historical figure (1865-1959), he is portrayed as an art historian and critic who constructs a persona to achieve his ambitions. Bernard initially appears to be an outsider like Belle, with a claim to uplift the common through art, but his actions reveal a self-interested nature that contrasts with Belle's focused ambitions.

Based on Richard Greener (1844-1922), a civil rights activist, the first Black Harvard graduate and professor at the University of South Carolina. He is characterized by his commitment to racial equality and his nurturing of Belle's interest in art. While initially an idealist, his stance evolves over the years.

Based on Anne Tracy Morgan (1873-1952), daughter of J.P. Morgan. In the novel, Anne is an antagonist to Belle, suspicious of her identity. Despite their conflicts, Anne shares similarities with Belle, as both navigate closeted aspects of their lives, revealing how class can mitigate societal norms.