Sonia is a 33-year-old scientific illustrator who accepts a position at a decaying estate in rural North Carolina. Possessing a meticulous mind, she processes the world by analyzing how she would paint it. Her financial precarity leaves her vulnerable to her employer's harsh demands, though her innate curiosity pushes her to investigate the strange occurrences around the property.

Dr. Halder is a reclusive, abrasive entomologist who specializes in parasitic and necrophagic insects. He resides in a decaying North Carolina estate and treats everyone around him with equal disdain. He demands absolute perfection from his staff and harbors deep resentment toward the mainstream scientific establishment, particularly the Megatherium Club.

Rose is the capable, no-nonsense Black housekeeper at the Halder estate. She maintains the household despite her employer's mean-spirited nature, choosing to stay because Halder does not discriminate against her interracial marriage. She provides a source of stability and warmth in an otherwise hostile environment.

Jackson is a white handyman who works on the Halder estate. He possesses a kind, humorous demeanor and freely shares local folklore and history with the household. His steady presence and willingness to trap specimens for the doctor make him an essential part of the estate's daily operations.

Asa is a grimly devout local man who operates with a fanatic worldview. He views the surrounding woods as a place of literal demonic danger and claims to have seen the Devil firsthand. His strict religious beliefs lead him to scrutinize the morality of those around him, including the estate's new illustrator.

Louisa is Dr. Halder's estranged wife and the previous scientific illustrator for his research. She possesses immense artistic talent and a warm, sensitive nature that is preserved in her personal sketchbooks. Her attempt to elope from her abusive marriage resulted in tragedy, leaving her fate a subject of local gossip.

Saul is a handsome man who fell in love with Louisa Halder and attempted to help her escape her abusive marriage. According to local history shared by the estate staff, Dr. Halder intercepted their elopement and shot Saul. His reported death and unmarked grave cast a long shadow over the estate.

Ma Kersey is a respected Lumbee healer who understands the strict social hierarchies of rural North Carolina. Operating independently of the white power structure, she serves as a keeper of local folklore and medical knowledge. She provides crucial context about the region's history and the tragedies surrounding the Halder estate.

Sally is a young white maid working at the Halder estate. She harbors a deep fear of the surrounding woods and readily shares local superstitions with newcomers. She specifically warns Sonia about mythical entities that drain victims of their blood.

Esther is Sonia's former roommate. She previously criticized Sonia for drawing ordinary plants instead of more commercially viable subjects. Her memory highlights the professional and financial pressures Sonia faces.