Eighteen-year-old Mary Katherine, who usually goes by Merricat, lives an isolated life at Blackwood Manor with her sister and uncle. Following a tragedy that claimed the rest of her family six years ago, she maintains strict daily routines and relies on sympathetic magic, such as burying talismans and reciting charms, to protect her home. She harbors intense resentment for the surrounding townspeople who mock her family and fiercely guards her sister from any outside influence.

Constance is Mary Katherine’s older sister and the primary homemaker for the surviving Blackwoods. After being tried and acquitted for the arsenic poisoning that killed the rest of their family, she developed severe agoraphobia and refuses to leave the estate. She fills her days by cooking, preserving food in the cellar, and maintaining a facade of normal domesticity for her sister and uncle.

Uncle Julian is the elderly, wheelchair-bound survivor of the poisoning that devastated his family six years ago. The ordeal left him physically frail and prone to mental wandering. He spends his days organizing his notes and obsessively talking through the details of the murders, hoping to compile a definitive historical account of the tragedy.

Charles is a 32-year-old cousin to the Blackwood sisters who travels to the estate following the death of his estranged father. He presents himself as a protective relative stepping in to manage the household, but he quickly shows a keen interest in the family's hidden safe and valuable possessions. His demands for normalcy threaten the fragile peace the surviving family members have constructed.

Helen is one of the very few villagers who maintains active social ties with the Blackwoods. She makes scheduled visits to the estate for afternoon tea and continually encourages Constance to step outside her self-imposed isolation, believing the family needs to reintegrate into local society.

Mrs. Wright is a local woman who tags along with Helen Clarke during a visit to Blackwood Manor. She displays a morbid curiosity about the family's tragic history and listens eagerly when Uncle Julian begins recounting the day of the poisoning.

Jim is a prominent town gossip who embodies the village's collective hostility toward the Blackwood family. He openly taunts Mary Katherine during her errands, passive-aggressively suggesting she and her family should move away from the village.

Stella runs a local cafe in the village. Unlike most of the townspeople, she remains relatively civil to Mary Katherine when the young woman stops in for a cup of coffee during her grocery runs.

Dr. Levy is the town physician who makes routine visits to Blackwood Manor. He efficiently assesses Uncle Julian's health without engaging in the gossip or judgment that occupies the rest of the village.

Jim is Helen Clarke's husband. He maintains a distant but steady connection to the Blackwood family, occasionally checking on their welfare alongside other village professionals.

Jonas is Mary Katherine's loyal pet cat. He follows her during her daily routines and patrols, acting as a silent, non-judgmental confidant in her highly isolated life.

John was the wealthy patriarch of the Blackwood family and the father of Mary Katherine, Constance, and Thomas. He died alongside several other family members in the arsenic poisoning six years prior to the story's events. His belongings remain untouched in his bedroom until Charles arrives.

Ellen was the mother of the Blackwood children. Before dying in the family poisoning, she instituted the high fence around the property to keep the townspeople out, establishing the family's physical isolation.

Dorothy was Uncle Julian's wife who died during the fatal dinner six years ago. Her memory is kept alive primarily through her husband, who often calls out for her in his moments of cognitive decline.

Thomas was the younger brother of Constance and Mary Katherine who died during the mass poisoning of the family six years earlier.

Arthur was the brother of John and Julian Blackwood. His recent death leaves his son Charles free to travel to the surviving Blackwoods' estate.