plot-bunny: Highlander/Tortall
Tamora Pierce writes young adult fantasy books. (I like this author a great deal, and since I have just finished reading her most recent publication, I of course have an idea for a crossover.) One of her two universes focuses on a country named Tortall in a land where Gods, gods, magic, and immortal creatures, are all real and wander the land. Since two of the quartets set in Tortall are focused on the heroine becoming a knight of the realm, there is a fair bit of discussion of "The Ordeal," which is the final test for all squires who wish to become knights, and "The Chamber of the Ordeal," which is where this test is located.
"The Chamber of the Ordeal" is a magic room with iron doors. This room judges and tests the applicants with visions and horrors, and the applicants must remain silent both in the chamber and refuse to speak of their visions to anyone at a later time. The reader has seen the visions of two successful applicants and these visions seem to be of them failing miserably to protect their friends and family. Since our heroines refused to be put off by this, they succeeded. From the outside, the reader has seen various bad guys go into the chamber and come out either dead, insane, or under a geas to admit their sins.
Only applicant Knights are allowed into the Chamber, and they only go the one time.
The Chamber has power of an unknown sort and has knowledge of things far away both in place and in time. It may even be sentient.
The setting is vaguely middle ages. Thus, for a crossover with Highlander, let us say that it has been some millenia since the Horsemen road, and some centuries yet before the modern age.
So the idea I had is that the Horsemen broke up more or less gracefully. The brothers decided it was time to part. They were starting to rub each other the wrong way, civilization was starting to develop to the extent that four riders were going to get in trouble no matter how immortal they were. So they went their separate ways, still friends and brothers. Just not, er, coworkers, as it were.
In canon, we see them three thousand years later. That's plenty of time for Caspian to have gone completely around the bend. Silas is slow and pleasant and wants what his brothers want. Methos doesn't want to restart the Horsemen. So what happened to Kronos?
I have an idea that Kronos was in Tortall for a period. Maybe he was working as a swordsmith at Raven Armory, the best armory in all Tortall. He's happily married into the Raven clan. Everything is good.
However, being part of a clan makes him miss his brothers. He wants to introduce his brothers to his wife and family. He sees his brothers every couple of centuries whenever they cross paths but he never knows how to find them. And then he learns of the Chamber. So he goes into it, searching for information on his brothers and figuring, hey, he's immortal? What can the Chamber do to him?
Unfortunately, what the chamber can do to him is attempt to kill him and maybe not drive him mad, per se, but certainly give him an obsession for knowing where his brothers are and a terrible fear that they're all dead or will be without him to stand guard and keep the rest of the world back.
This story is a tragedy. It's a story of Kronos' hubris coming back to kill him and a great many other people in addition over the course of the next ~500 years. And it's a story of The Chambers' hubris coming back to bite it, because it tried to kill an immortal and only succeeded in releasing a more dangerous foe into the land.
...
However, I don't much care for tragedies.
An alternative: Kronos was a real knight applicant. Maybe he did the kingdom some favor and was granted nobility. Then he went through the whole knight training process because the idea of Kronos being in class with a bunch of uppity teenagers is just too funny. And then the entirety of the Kronos' canon plot arc is a vision from the Chamber to test him.
The old tried and true it-was-just-a-dream fix.