These days, Rarity is one of the most successful designers in Equestria, but that wasn't always the case. It wasn't all that long ago that Rarity was just starting out, a largely unknown up-and-comer...who somehow had been able to open her own boutique.
One day, while visiting their friend, Applejack and Fluttershy overhear an argument that threatens to reveal the secret as to how Rarity managed to afford to open Carousel Boutique, a secret she had hoped would never see the light of day.

Rarity is good at making dresses. In fact, she's the best. But even she didn't know that her latest dress would be more than the fashion sensation of the season.

Now she was going to have to add wing-holes to all her outfits, and everypony seems worried about her latest creation.

Chrysalis kidnaps Rainbow Dash and holds her for ransom.

This same Rainbow Dash also happens to be engaged to the immensely powerful Alicorn Princess Twilight Sparkle.

Chrysalis is not a very smart changeling.

When a scheduled snowstorm goes awry, Rarity and Sweetie Belle are left snowed-in at the Carousel Boutique. They try their best to have a fun, worthwhile day nonetheless. A sweet, fluffy, lighthearted oneshot.

Rarity explains to Sweetie Belle what the Cutie Mark Crusaders saw when they walked in on her and Applejack.

It was totally innocent. Really!

There is now a Spanish translation of this story, courtesy of Spaniard Kiwi

Celestia finds herself sharing company and her booze stash with Luna's crazed split-personality, Nightmare-Moon. However, as the night wears on, she finds she may actually be able to tolerate the dark alicorn. Maybe even like her.

For Nightmare Moon is the best pony: Contest numero uno.

Applejack realizes one morning that Rainbow Dash has apparently moved in with her. This discovery surprises Dash more than a little, too, and sets off a chain of events neither could have imagined.

The original minific version of this story came in fifth in the Dec. 2015 Writeoff Association contest, "Things Left Unsaid." And the full, three-chapter-and-an-epilogue version won 3rd place in The Fourth AppleDash Contest: A Little Twist of Lemon using the categories "A Life-Changing Event" and "An Important or Memorable Date."

A secret unknown to any hornless pony, unicorn horns are made of candy. Pinkie Pie found out, and now she wants to try every flavor!

Warning: contains awkward moments and far too much non-consensual horn licking. Proceed at the risk of your horn and your dignity.

Available in Chinese, courtesy of Hell Organist.
Available in Russian, courtesy of boatOV.
Audio Reading by CaptainBron3y.
Second Audio Reading by Kanjigirl.
Featured on Equestria Daily.

Based on this story:
Pegasus Wings Are Made Of Ice Cream
The Taste Of Madness
Lyra's Candy Shoppe
Candy Is Made Of Unicorn Horns
How Many Licks?
To Prevent Horn Decay
Unicorn Horns Are Made of Heroin
Over His Dead Body
A Luscious Loophole
Dr. Doofenshirtz's Sweet Revenge
That Thing We Do
#DealWithIt
Unicorn Horns are...
Unicorn Horns Are Loaded With Calories
Charlie The Unicorn's Horn Is Made Of Candy

Princess Twilight Sparkle discovers a centuries-old mystery hidden in the Royal Archives. Her investigation leads through layer after layer of deception and misdirection, setting her hooves on a path that seems to be leading to a mysterious secret. Along the way, she learns that some friendships can be very, very strange.

Book 1 of the Alicorn Adventure series.

AUDIOBOOK by VisualPony
Featured at the Royal Canterlot Library
TV Tropes Page (Courtesy of Sandtalon)
Goodreads Page (Courtesy of Facedeer)
Equestria Daily Page

WARNING: Major spoilers in the comments. Takes place several months after the end of season four. (Not a Da Vinci Code crossover, BTW!)

Do you see a dark tag? No, you don't. Not dark. Well, okay, there are a couple of dark-ish bits, but that's all. Not enough to warrant a tag. Speaking of tags, there really ought to be "Badass Twilight" and "Friendshipping" ones.

Sequels and side-stories (and more) can be found here Offprint and AO3, and a hardbound two-volume set of all that can be ordered from The Ministry of Image.

My editor for the first edition of this story was Gogito, and I can't thank him enough for all the hard work he did. My editor for the revised version was PresentPerfect, and he did a terrific job of getting the story into excellent shape.

This story is a sequel to A Lascivious Rainbow Dash and a Shared Bath in Tomato Broth

Rarity wakes one night to find that her mane has detached itself from her head and packed its bags. Her mane tells her that it is leaving to pursue new ambitions, alone, without her. Their time together is at an end, it tells her, but the blissfully sweet years they shared will never be forgotten. Before it says its final farewell, they make love together one last time under a moonlit starry sky.

This was written as a standalone story. Reading the previous story is entirely unnecessary.