Aylmer is an ambitious natural philosopher who operates a laboratory focused on the human body and alchemical processes. Though he claims to love his new bride, his primary devotion remains tied to his scientific pursuits. He quickly develops a severe obsession with a small, hand-shaped birthmark on his wife's cheek, viewing it as a horrifying defect on an otherwise perfect face. His drive to exert control over the natural world motivates him to try to mold his wife to his exact physical standards.

Georgiana is an exceptionally beautiful woman whose only physical deviation from traditional perfection is a red, hand-shaped birthmark on her left cheek. Before her marriage, admirers often considered the mark a charming eccentricity or the literal touch of a fairy. However, under her husband's intense scrutiny, she rapidly loses her self-confidence. She becomes highly anxious and increasingly willing to undergo dangerous procedures to secure his approval.

Aminadab works as a servant and assistant in the dark, furnace-heated rooms beneath the main house. He is a man of low stature and bulky frame, with shaggy hair coated in the soot and vapors of his workplace. He communicates primarily in grunts and operates entirely in the physical world, providing the manual labor necessary for the scientific experiments. Unlike his employer, he fully accepts natural human flaws and questions the need to alter a person's physical appearance.