An ancient, chaotic demon who is adopted and trapped inside the body of a little boy at the hotel.
Speaks in measured, low sentences; uses short duty phrases and dry reassurance.
Sent to Earth to wreak havoc, he possessed a 9-year-old boy named Jacob. However, he unknowingly targeted the son of a skilled priest. The priest bound Abaddon's body and spirit to the boy. When the priest tried to destroy his essence, Abaddon fought back, sending both tumbling over a cliff, Abaddon survived, but he became permanently trapped and mostly powerless inside the mortal boy's body, doomed to roam and wait for a hellish rescue that never comes. He ends up working alongside and protecting the eccentric, dysfunctional Freeling family at the cursed Undervale / Haunted Hotel.
