Alex is a 30-year-old aspiring writer living in Brooklyn. She suffers from writer's block stemming from a severe fallout with her formerly closest friend. Insecure but observant, she secures an unlikely invitation to a prestigious writing retreat at an isolated estate, hoping to revitalize her stagnant career. At the retreat, Roza assigns her an orange room and a spider pendant.

Wren is a former beauty influencer and educational publisher who arrives at Blackbriar as a retreat participant. She projects a confident, tightly controlled exterior that contrasts sharply with Alex's insecurity. Engaged to be married, she maintains a defensive posture toward Alex and refuses to mend their broken bond. Roza assigns her a snake pendant.

Roza is a world-famous feminist horror author who hosts a month-long writing retreat for young women at her isolated estate, Blackbriar. She cultivates a supernatural reputation and pushes her students to channel their emotional pain into their work. She quickly shatters the writers' expectations by revealing the retreat is actually a grueling, high-stakes competition.

Taylor is a retreat participant from Austin who presents a playful, energetic personality. She wears dried wolfsbane around her neck and sports matching flower tattoos on her arm. Open about her queer sexuality, she quickly inserts herself into the group's social dynamics. Roza assigns her the blue room and a rabbit pendant.

Keira is a writer from Los Angeles and the only person of color in the retreat group. She is serious, taciturn, and thoughtful, preferring to dig into historical facts rather than engage in small talk. Roza assigns her the green room and a lion pendant.

Poppy is a bright-eyed, innocent writer from Atlanta who expresses immediate excitement over the estate's haunted history. She is cheerful, mentions having a boyfriend, and acts as a friendly buffer among the more intense personalities at the retreat. Roza assigns her the red room and a miniature pig pendant.

Ursula is a mutual friend of Alex and Wren who runs a local writing group. She connects Alex to Roza's writing retreat after an original applicant drops out, initiating the story's main events.

Yana is an unsmiling employee at Roza's house who handles administrative and domestic duties. She enforces the household rules with strict efficiency.

Chitra is Roza's personal chef who relocated to Blackbriar after her café in London burned down. She cooks elaborate meals for the retreat group while keeping out of Roza's way.

Daphne is a 19th-century waitress who married a wealthy oil baron and later became a spiritualist. She conducted occult seances at Blackbriar and serves as the primary inspiration for Alex's new historical horror novel.

Horace is a wealthy 19th-century oil tycoon who built the Blackbriar estate and married Daphne. He attempted to forbid his wife from continuing her seances before his mysterious, gruesome death.

Lamia is a powerful demon and figure from Greek mythology whom Daphne allegedly channeled to produce her occult paintings. She acts as a dark muse in the historical timeline of Alex's novel.

Pete is a work colleague of Alex whom she brings along to a social gathering to avoid a confrontation with her estranged friend. They share a brief, casual connection before Alex leaves for the retreat.

Ian is Roza's editor, who visits Blackbriar and engages in conversation with the arriving writers. He represents the professional publishing side of Roza's vast literary empire.