While reading a book about other dimensions, Twilight discovers inside a couple pieces of paper: one that's a recipe for a potion, and one that has a new spell on it. After further investigation, Twilight discovers the spell to be one that can teleport her across space, time, and dimensions to a whole new place. After successfully creating the potion and taking it, Twilight develops brand new powers that are completely separate from her magic.
With Celestia's recommendation, Twilight travels with the spell to a whole new universe where she meets Kaleb Foss, a Jedi. She joins him on his ship, the Ebon Hawk, where she travels with him across the galaxy to learn about it and her new powers.
This is a Star Wars: KOTOR 2 crossover that assumes the exile was a light side Jedi who left his friends to explore the galaxy. I know that more back story about all of that is revealed in TOR, but I'm just going to disregard TOR, since that would require me to actually play it to get my info. That, and it would probably throw my story way out of whack.
This story is set very shortly after the exile defeats Darth Traya and leaves Malachor V alone on the Ebon Hawk.
(I've went ahead and marked this Teen Sex for now, and added the Romance tag. There will probably be sexy romance stuff later, but I'll probably have it separate from the main story, sort of like in the story Green. Again, this is subject to change.)