Twilight gets a distressing letter from Celestia and rushes to Canterlot.
What happened to the princess? What is Luna up to? Why do I sound like the narrator to a bad crime drama?
The first chapter is inspired by a drawing from JohnJoseco. The rest will be my own madness doing its part.

Princess. Alicorn. The pillar of all ponykind, against which so many ponies often judged themselves. Celestia hates having to constantly be these things, and it's past time for a break. Luna will watch over Equestria while her sister is gone, but taking a break from your duties and taking a break from how the world sees you are two very different matters. Enter Prominence, a quiet pony who nopony really pays much mind to. Perhaps because she doesn't exist.

Aided by this disguise, Celestia will find her peace and relaxation in the home of one of the few ponies who know Prominence's true identity: Princess Twilight Sparkle. But when Twilight begins to see Celestia as a pony, and not a princess, can she deal with the feelings that arise? And are the feelings for Celestia, or for a pony she knows is not actually real?

EDIT: I've been featured, July 19th, 2014. I have no words to express how terrified and humbled and terrified and proud and happy and terrified this makes me.