Theo is a young woman who works at a bookstore and has a constructed sense of identity, using her chosen name to distance herself from her troubled past. She grew up in a strict, fundamentalist household with her adoptive parents, leaving her with fragmented childhood memories and a deep need for belonging. She feels out of place among the wealthy Dalton family, and her anxiety increases when she receives anonymous threatening texts upon arriving at their estate. Her curiosity drives her to investigate the disturbing history of the Dalton property, even as she attempts to secure a safe future with Connor.

Connor is Theo's fiancé and an heir to the extremely wealthy Dalton family. He idealizes his late father, Liam, whose tragic death at the Idlewood estate continues to cast a long shadow over his life. Connor appears highly protective of Theo and wishes to integrate her into his family's holiday traditions. He struggles to balance his affection for her with his loyalty to his family's rigid social expectations and intense focus on their public reputation.

Liam is the deceased father of Connor, Alexis, and Trevor, whose presence lingers heavily over the Dalton family's winter retreat. He reportedly died young after a fall from a roof at the Idlewood estate. His family members remember him with a mix of reverence, grief, and unspoken tension. His untimely death serves as the catalyst for many of the family's current dysfunctions, particularly Connor's deep-seated need to protect his memory.

Alexis is Connor's older sister, fiercely protective of her family and highly skeptical of newcomers. She is married to Paloma, and together they are raising their young son, Sebastian, at the holiday retreat. Though initially abrasive toward Theo, she demonstrates a surprising capacity for empathy during quiet moments. She offers Theo a conditional alliance, making it clear that she will intervene if anyone hurts her brother.

Rose is Liam's widow and the mother of Connor, Alexis, and Trevor. She maintains a genteel, tightly controlled exterior and scrutinizes Theo's presence and appearance with obvious disdain. As a woman who married into the powerful Dalton family decades ago, she harbors quiet regrets about her past. She uses her experience to advise Theo on the harsh realities and legal necessities of marrying into immense wealth.

Trevor is Connor and Alexis's brother, known within the family for his reckless behavior and substance use issues. He resents his relatives' constant judgment while simultaneously relying on their wealth to shield him from the consequences of his actions. He adopts a hostile and boorish attitude toward Theo from their first meeting. His erratic presence at the holiday gathering frequently forces uncomfortable family secrets into the open.

Magnus is the imposing patriarch of the Dalton family, wielding immense wealth and absolute authority over his relatives. He values strength, legacy, and hunting skills, sizing Theo up by inviting her to help him process a hunted deer in the freezing cold. He runs the family like a corporate empire, prioritizing the protection of the Dalton name above individual happiness. He views his grandson's rapid engagement with intense scrutiny and suspicion.

Louise is the matriarch of the Dalton family, operating as the strict gatekeeper to their inner circle. She is deeply suspicious of outsiders who might threaten their carefully maintained social standing or financial security. She demands perfection from her family and shows clear, immediate disappointment when Theo's working-class background does not align with her elite expectations. She uses her position to interrogate guests and control the family's private narrative.

Nick is Connor's uncle and a doctor who steps in to handle medical emergencies at the isolated Idlewood estate. He has recently separated from his wife and seems to carry the weight of past family tragedies. He asks probing questions about Theo's childhood that make her distinctly uneasy. His quiet presence hints that he knows more about the estate's dark history and the abandoned fifth cabin than he initially lets on.

Daniel Vance is the groundskeeper and caretaker for the sprawling Idlewood estate. He monitors the property with his dog, Duchess, keeping a watchful eye on the Dalton family's guests and the surrounding woods. He possesses extensive knowledge about the estate's history, including the neglected fifth cabin where Liam died, and strictly enforces the family's boundaries.

Paloma is Alexis's wife and the mother of their young son, Sebastian. She manages the intense Dalton family dynamics alongside her wife, bringing a grounding and observant presence to the fraught holiday gathering. She is keenly aware of the family's tension and watches how they treat outsiders.

Sebastian is the young son of Alexis and Paloma. He provides a rare point of innocence amid the tense Dalton family gatherings. He forms a brief, quiet connection with Theo when she reads him a children's book.

Irina is the primary housekeeper at the Dalton family's Idlewood estate. She works alongside her daughter, Olena, to serve the demanding family during their winter retreat. She maintains a professional distance while witnessing the family's intense personal conflicts.

Olena is Irina's daughter, who helps maintain the estate during the holiday gatherings. She appears visibly tense while working for the Daltons and becomes secretly entangled with the family's turbulent younger generation. Her presence at the estate exposes the stark class divide between the staff and the wealthy family.

Beth is Theo's adoptive mother, who raised her in a strict, fundamentalist religious household. She used religion as a tool for control and subjected Theo to severe physical and emotional abuse. Her harsh treatment left lasting psychological scars that Theo still carries into adulthood.

Joseph is Theo's adoptive father, who remained emotionally distant during her childhood. He stood by while his wife Beth inflicted severe abuse, making him complicit through his inaction and compliance with their church's rigid rules. He contacts Theo unexpectedly, breaking years of silence.

Harper is a photographer and Theo's close friend from back home. She acts as an external anchor for Theo, representing her independent life away from the overwhelming influence of the Dalton family. She introduced Theo and Connor after an art gallery showing.

Mallory is a woman from the Dalton family's past who lived in the abandoned Dragonfly cabin around the time of Liam's death. Nick claims she was Liam's mistress, and her mysterious disappearance remains a closely guarded family secret. Photographic evidence suggests she suffered physical abuse before vanishing.

Duchess is Daniel Vance's loyal dog. She follows the groundskeeper as he patrols the Idlewood estate, providing him with companionship in the isolated mountain setting. She acts protectively toward those she encounters on the property.