i actually think that Hell HAD to have purposely have sent Abaddon to get exorcised by the priest
like. I fully believe they sent him there with the intention of never seeing him again.
i mean, for one, Abaddon had been *sent* to Earth on his 10kth year, possibly meaning this specific location had been set for him to land.
he ends up Happening to land where a Highly Skilled Priest resides.
and Happens to possess the child of this priest, because he was under impression that it was a Popular trend
mind you, this area also JUST SO HAPPENS to be a hotspot for the supernatural, which i feel like might be related in some way.
and then, for years, no one comes for him. we aren’t told when exactly Abaddon’s castle was destroyed, but we know it had to have not been very recent for Mortoth to completely forget about it and him. for all we know, they had gotten rid of his castle the moment he left and didn't come back
anyways, another long post
(and also technically some Priest headcanons)
Vessel’s name is Isaac (It was either that or Zachariah)
He is nine years old (the youngest person ever)
Would commune with the ghosts and other supernatural beings in the area
His mother was a ‘witch’—she was a woman of faith, though witchcraft was a practice passed down in her family that she had to let go of when she ended up with the Priest.
The Priest was just like any father in the 18th century. not very ‘loving’. and like any religious figure in the 18th century, he was very strict
In this era, children were seen as sinful and depraved because they lacked proper socialization, and were born from sin. They were believed to be lost in sin until brought to faith in Christ. Isaac was under strict discipline. He was expected to be obedient, and he was put to work at a young age. (Corporal punishment was very common and often severe. In Puritan beliefs, they seem to emphasize the need to "break" a child's will and teach them to fear sin.)
Basically, he was treated like a small adult.
Isaac had been taught not to express any extreme emotion. Though, his mother was often kinder with him, and was always soft on him when they were alone. (it was the norm to establish emotional distance from your child during this time)
Autistic, and has very bad eyesight and would struggle to read verses. Because of this, before Isaac had actually even been possessed, The Priest was already under the impression that Isaac was under some sort of demonic influence
Isaac and Abaddon’s relationship was very weary in the beginning, of course. Now, their interactions are (begrudgingly, on Abaddon’s part) familial.
Isaac is not conscious within the vessel, and has been in a sort of resting state for a while. so he hasn’t really aged.
If he were to ever interact with Katherine, he would be very attached, for she reminds him extremely of his mother
inspired by @neo-exploded’s headcanon—Abaddon can communicate with Isaac through reflections.
When Isaac is in control of the vessel, he can communicate to Abaddon through shadows.