Welcome to the land of Ice and Fire! In this story, you play as the newly crowned King Jaehaerys Targaryen (aka Jon Snow), Third of His Name and Lord of Westeros.
This is an alternate reality story, in which the Targaryens defeated Robert Baratheon in his rebellion. Good luck!
(Disclaimer: This is written in the same Westeros as the books, not the show, and therefore you may find some things are different if you have only watched the show)
Epileum