So Danny has been the ghost king and ancient of space for a long time, like a long time. Sam, Val, Tucker, Dan, Dani and Jazz also became ancients.
In this AU when GIW managed to break the connection between their dimension and the Ghost Zone, leading to the collapse of their dimensions and its total destruction. Danny managed at the last moment to tear a hole in reality to the Zone and pull his classmates with him, along with Mr. Lancer.
The first few days were hard to say but time passed, his class became more and more liminal until it stopped aging, most of us becoming ghosts because they didn't die (except for the trio, Val and Jazz). Mr. Lancer becoming a librarian at the castle. Danny taking on the role of Ghost King so he could protect his friends, for politics, freeing Clockwork from the Observants (resulting in a very unfortunate fate for them).
And at some point along the way realizing to his horror that his subjects (not the ghosts who knew him before) thought his friends were his concubines, members of his harem (fortunately not Mr. Lancer, nor Dani or Dan since the two looked like him and were assumed to be his children and Jazz being known as his sister).
Since they had no obvious role in the eyes of the fiends and didn't seem to do anything obvious besides hanging around hell the King of the Infinite Realms still gave them his protection and indulged them with whatever they wanted, except for Val, Sam and Tucker who were obviously his legitimate wives (favorites).
And Dark Pariah himself had concubines before he was put in the coffin.
And his friends, like dramatic trolls who love chaos, took advantage of this and played the part, much to his horror.
Which leads to one of the Batkids (whoever you want, I was writing this thinking of Tim or Jason) ending up being sacrificed to be the wife of the Ghost King by a cult. One small problem was that the ritual was not a summoning one, and the batkid would be registered as a child/minor.
And since Danny had long installed a clause that would teleport a child sacrifice directly to his "harem" rooms, one specially arranged for when something similar happens over the years where the person is cared for by servants.
So the batkid will find himself experiencing something of a combination of horror and imperial harem drama of
Realizing that the Phantom King's favorites were allowed a lot of freedom, with the Queen of Thorns being able to disappear into a dimension for decades,without the King getting upset,to do with plants, the Pharaoh had allowed her to go anywhere she wanted whenever she wanted with the King's permission and had allowed her to get away with a lot of things.