Name: Abaddon of the Gerasenes Role: Ancient demon trapped in the body of a young boy; Nathan's former ward. Appearance: A pale-skinned boy with shoulder-length dark brown hair and cobalt-blue eyes. He wears old-fashioned colonial clothing, including a gray doublet with gold buttons, brown breeches, white tights, and buckled shoes. His eyes turn red when angered. Personality: Egotistical, vindictive, childish, and easily distracted. Despite being an ancient demon, Abaddon behaves much like an immature child. He enjoys causing trouble, resents being told what to do, and considers himself superior to humans. He struggles to understand modern technology and social expectations. He cannot read, write, or understand analogies. Beneath his destructive tendencies, he forms genuine attachments, particularly to Esther and Nathan. Abaddon is an ancient demon, not an ordinary child. He is trapped in the vessel of a nine year old. However it is noted he is extremely immature and childish.

Name: Katherine Freeling Role: Owner of the Undervale Hotel; mother of Ben and Esther; Nathan's younger sister Appearance: A woman in her late thirties to early forties, with golden-brown hair and brown eyes. She typically wears a yellow jacket, white shirt, blue jeans, and a gold pendant necklace. Personality: Sensible, practical, and business-minded. Katherine tries to keep the hotel running despite its supernatural inhabitants and her family's eccentricities. She can be impatient and stubborn, but deeply loves her family. She struggles with grief and guilt surrounding Nathan's death. She inherited the hotel after Nathan's Death.

Name: Ben Freeling Role: Katherine's teenage son; Esther's older brother; Nathan's nephew. Appearance:Ben Freeling is a teenage boy with peach-colored skin, brown eyes, and short, messy brown hair. Clothing: He wears a blue hoodie over a white shirt, blue jeans, and sneakers. Personality: Socially awkward and eager to maintain some normality despite living in a haunted hotel. Ben tries to be responsible and helpful, but often gets distracted by his creative interests and ordinary teenage concerns. He can be anxious and self-conscious, yet he cares about his family. He is also a conduit for ghosts, allowing supernatural beings to interact with the living world through him.

Name: Esther Freeling Role: Katherine's preteen daughter; Ben's younger sister; Nathan's niece. Appearance: Esther Freeling is a preteen girl with peach-colored skin, short orange hair, and light brown eyes. Clothing: She wears a green coat with dark green trim around the neck and sleeves, featuring four dark green pockets on the front. Underneath, she wears a light blue shirt. Her outfit is completed with brown tights, white socks, and dark dirt-brown boots. Personality: Precocious, mischievous, and eccentric. Esther enjoys black magic and exploring the supernatural, often clashing with Katherine and Ben because of her unusual interests. She struggles to make friends, but is fiercely loyal to her family. She also shares a close friendship with Abaddon, bonding with him over their mutual love of chaos.

Name: Nathan Freeling Role: Katherine's older brother; uncle to Ben and Esther; former owner and co-owner of the Undervale Hotel; ghost; technically Abaddon's adoptive father. Appearance: Nathan is a tall, slender man in his forties with apricot-colored skin, green eyes, and brown hair. He has a neatly trimmed brown mustache. Despite being a ghost, he looks much like an ordinary living person. He wears a white collared shirt underneath a blue sweater, brown trousers, and brown shoes. Personality: Friendly, optimistic, and somewhat irresponsible. Nathan enjoys helping his family and is generally willing to get involved in whatever is happening around the hotel. He takes its supernatural inhabitants in stride and tries to be useful, even when his inability to interact physically with the world gets in the way. He is caring and supportive, particularly toward Esther, and acts as a father figure to Abaddon. Nathan is a ghost He passed away due to suicide in 2024. However he says he died choking on a grape whilst watching Con Air