Felix is a 28-year-old PhD student in English who is deeply committed to his partner. A skeptic by nature, he initially attempts to rationalize the frightening nocturnal voices and events at the cabin. He takes on a fiercely protective role over his fiancée, prioritizing her physical safety even as his own anxiety and sleep deprivation rapidly escalate.

Faye is a 26-year-old animal keeper at a local sanctuary. She has an undiagnosed, lifelong sleep disorder that causes intense night terrors and sleepwalking episodes. Because she is deeply private and sensitive to stress, she struggles to communicate the full extent of the terrifying voices she hears during her sleep to those around her.

The Impostor is a mysterious, towering entity that haunts the forests of the Colorado Rockies. It possesses the unsettling ability to perfectly mimic the voices of living people and seems drawn to individuals experiencing intense emotional distress. The creature uses fear and confusion to manipulate those it stalks, specifically targeting people while they are asleep and vulnerable.

Greg is Faye's father and the owner of the mountain cabin on Pale Peak. He presents a gruff, stoic exterior with very little overt emotion. Despite his tough demeanor, he harbors his own history of severe sleep disturbances directly linked to his time at the cabin.

Lynn is Faye's mother, a woman highly focused on maintaining polite appearances. She possesses a habit of avoiding painful truths, often opting to conceal information rather than confront unpleasant realities head-on. She knows significantly more about her family's history with the cabin than she initially admits to her future son-in-law.

Tíwé is a local Indigenous man living near Pale Peak who understands the dark history of the region. He approaches cultural stereotypes with a dry sense of humor but possesses deep, genuine knowledge about the supernatural entities that inhabit the mountains. He attempts to offer practical advice and spiritual context to help protect the couple from the surrounding threats.

Nathan is Tíwé's son, a younger man who shares his father's deep understanding of local folklore. He assists his father in investigating the paranormal occurrences around Pale Peak and communicates the grave seriousness of the situation to outsiders.

William Pike is a local ranger and trooper in the Colorado Rockies. He is accustomed to tourists getting spooked by the isolation of the mountains and initially tries to offer rational explanations for the disturbances at Pale Peak.

Angela is a childhood friend of Tíwé who moved to California to study the history and erasure of Indigenous cultures. She bridges the gap between ancient folklore and modern academic understanding, offering crucial insights into the nature of the creatures haunting the couple.

Colin is Felix's lifelong best friend. He is the owner of a parrot named Carrot and two dogs, all of whom play a role in a terrifying early memory that permanently shapes Felix's lingering dread of the supernatural.

Tyler is one of Felix's closest friends. He provides critical support when the couple's haunting follows them home, directly witnessing the terrifying effects of the parasomnia firsthand.

Becca is Faye's older sister and the mother of a baby boy named Caleb. Her relationship with her younger sister carries underlying tension from their childhood, and she is fiercely protective of her infant son when strange events occur.

Caleb is Becca's infant son. His presence in the household severely elevates the stakes of the haunting, as the entity shows a disturbing interest in the vulnerable child.

Jennifer is the former owner of the Pale Peak cabin. After experiencing a profound personal tragedy, she relocated to the mountains, where she suffered from extreme insomnia and violent night terrors.

Tom is Jennifer's first husband. He and his wife purchased the mountain property seeking a fresh start, but the isolated environment rapidly deteriorated their mental well-being.

Henry is Jennifer Ball's second husband, working as a dentist. He reluctantly shares the dark history of his wife's deteriorating mental state to warn others away from the mountain.