Catherine Asaro's "The Spacetime Pool" (novella, alternate history, free)

Not a bad read, but you've probably read many stories with this general plot. Medieval society where two princes fight for a kingdom & a woman.

Story summary.

On a parallel earth, Maximillian & Dominick are twin brothers & heir to the empire of Othman (presumably their version of "Ottoman").

This is a curious world: There is a lot of knowledge in books & gadgets that suggests that half a millennium back, this was a highly technological society. But all that knowledge has now vanished, with only a few keepers of old relics - somewhat like Walter Miller's "A Canticle for Leibowitz".

Then there is a prophecy, by a monk named Gregor. One of the two brothers will marry a woman called Janelle Aulair; he will kill the other brother, & presumably inherit the empire. If either brother kills Janelle, he will die. There is a picture of Janelle available, at age 70.

By curious circumstances, Dominick will end up kidnapping Janelle from our world when she's in early twenties - using a gadget inherited from the ancient lost civilization. Story is mostly Janelle's adventures through this violent sword-wielding horse-equivalent-riding society.

Fact sheet.

First published: Analog, March 2008.
Rating: B.
Download full text from Analog site, or as an 8-part serial from author's blog (01, 02, 03, 04, 05, 06, 07, & 08).
Winner of Nebula Award 2008 in novella category.
Related: Stories from Analog/Astounding.