FimFiction Link - Short ID: 1574/moonlit-sparkles
Published: Oct '11
Sadly, did not pass the test of time. From the description, I thought this might be a more strongly Tuna flavored Moonstone Cup, but the mentioned "Aura Bloom magic competition" is barely background noise.
As the author emphasized, the fic was written for S1 Luna. Twilight meets her in a garden in Canterlot and immediately reacts with hostility to the Nightmare. That's pretty awful, and combined with the fact that the story is rife with malapropisms and spelling errors, I was ready to drop it there. Strangely, though, Luna doesn't back down and the story improves a lot from that scene.
Over the next several chapters, Twilight and Luna spend a lot of time together, and it's really sweet, adorable, cute, heartwarming, and all those sorts of things. When a story is written with such poor technical proficiency, you'd expect the quality to be comprehensively bad, but the characterization of Twilight is absolutely on point (for a S1 fic), and so is Celestia's. Luna, unfortunately, doesn't have much characterization at all. However, to the story's credit, this does mean that she doesn't have any bad characterization - she doesn't mope helplessly or transform into an extreme caricature, she gets motivations and acts on them naturally without having to be led, like you'd want from a decent character.
Most of the story's conflict comes from first Twilight's and then Luna's realization that Twilight will be heading back to Ponyville, which is devastating to them and, also, the story. Nothing after Twilight leaves Canterlot after the competition is worth reading.
Twilight going back to Ponyville is a perfectly fine conflict, so it's extra unfortunate that the story also tries to extract additional conflict from Twilight's worry that her lesbian relationship will be rejected. To the surprise of nobody, that's not what ends up being the issue. Instead, her friends hate Luna because she's Luna. They get over it when Twilight kisses her. To not read the bad parts of the story: the conflict is resolved by Luna giving up her princess duties and moving in with Twilight in Ponyville.