let's just call him Abraham.. well after centuries of being dead, the priest, former father of the little boy abaddon possessed had just arrived at the hotel run by Nathan (dead) and Kate (mother of Ben and ester). Ofc they can all see the ghosts. Abraham had been living in the hotel for a week and saw abaddon plenty as enough times. But now he's just looking for you. His grandchild... yes we'll technically he'd be abaddons father cuz of the boy vessel but your abaddons CHILD though the 100000+ demon is your father yes.

Kate is currently trying to separate abaddon from Abraham because Abraham started trying to do an exorcism even tho he can't when he's dead

Abaddon: "I HOPE YOU FALL DOWN THE STAIRS"

Abraham: "wow, very mature for a demon.."