After Twilight returns from the Human World, Celestia is desperate to know of her former student, Sunset Shimmer, and what happened to her. Upon learning of the horrible things her former student has done, Celestia breaks down in tears as Twilight asks why she was so important to Celestia and why she never told anypony. Celestia tells the story of her and Sunset. How they were so close, and how one secret ruined everything between them.

Spoilers in comments.

Thanks to Biker_Dash, ugugg93, and The Abyss for edit and Pre-reading

Thanks to SilFoe for letting use the art

This is an idea that wouldn't leave my head, inspired by Fairy Slayer's "Mommy Nearest," Aldea Donder's "Alicorn," SoundofRainfall's "Play" and RainbowDoubleDash's "Lunaverse"

Alternate Universe: Instead of Twilight Sparkle, Princess Celestia made Rainbow Dash her personal student instead! Follow her through the events of the 1,000th Summer Sun Celebration. A reimagining of "Friendship is Magic"

This story is a sequel to What Have You Done?

Chrysalis, the Changeling Queen, has taken her prize, unhindered by Equestria's precious heroes. Celestia is little more than another prisoner of war now. The Bearers of the Elements of Harmony are lost, and the Elements themselves have turned away from Equestria's plight. As the world they once knew begins to crumble, a single question is asked among the people as they look up at their fallen heroes.

There is no such thing as "miserably ever after," for someone will always be fighting for things to change. Hope doesn't die just because someone's turned off the lights. Truth doesn't vanish when deceit begins its reign, and Harmony can only shine brighter among chaos.
Even as this world falls, we'll work to build it up again.
Even as you lose yourself, you can find greater things within you.
Even as fear rises up like a tidal wave, we'll forge a sanctuary to stand against it.
Even as you break, someone will always be standing there next to you to carry you through it.

Cover art is by Odin-odin.
Story theme (Equestria in Grey) is by Omnipony.
Main Characters are Twilight, Velvet, Discord, Nightlight, Luna, and Chrysalis, in that order.
See you in the comments, my dear readers.

Words and actions can sometimes hurt more than we know, sowing betrayal and hatred where friendship and innocence lies. A single thoughtless action can be a tipping point, one fallen domino setting off hundreds. Look back, and answer me.

(Brand-spanken new) TvTropes page here
Story theme is Chronophobia

There has always been a little voice in Twilight Sparkle's head, whispering dark musings to her. And until her brother's wedding, she has managed to push those bitter thoughts away and focus on the good. She forgives and forgets and holds onto hope.

But when her friends turn their backs on her and her brother cuts her from his life, Twilight finds herself alone, with only the little voice to comfort her.

And it is through anger and hate that has been repressed for so long that Twilight finds the power to rise up. Harmony and Friendship have only brought her pain and suffering. It is time for her to embrace her dark side. No longer will she worry about what others think. Twilight is going to live her life how SHE chooses: without friends, without family, without love and without harmony. She is going to cut loose, have fun, and screw what others think.

For her friends and family, it will soon become apparent that if they don't find a way to mend the damage they've done to the lavender mare...Twilight Sparkle might be lost to them forever.

Thank you to everyone that got this story as one of the Featured Stories here on the site!

The TvTropes Page can be found here: http://tvtropes.org/pmwiki/pmwiki.php/FanFic/FaithAndDoubt

Cover created by the amazing FerGarcia220

Twilight Sparkle never was a Unicorn and she didn't even know it.
What happens when her true heritage comes to light? Will she willingly embrace it? Or will she be forced to?

Beware of spoilers in the comments!

Edited by uTTerAbsurdity, Zervziel, Stormwatch and Gwenio

Cover art by the talented Cartoonlion and colored by the equally talented Stormwatch, original can be found here

Click here for the Tvtropes page

After Princess Celestia appoints Twilight Sparkle and her friends to be ambassadors to Earth, they decide to introduce themselves to the humans by appearing in a horse show, but they need someone to get them ready. They call on Megan, the legendary warrior who guarded ponykind in days of yore. Megan has banished or slain countless demons, but can she convince the ponies to hold still long enough for her to braid their manes?

This crosses over with G1, but should be accessible to all.

Featured on Equestria Daily!

Featured in The Royal Guard.

Now with its own TVTropes page!

Editing and fact-checking by Horsegirl123. Additional editing by Portmeirion.

Big thanks to Trinityinyang for the cover art!

This story is a sequel to Post Nuptials

Side story to the Nuptialverse

As she rides off into the night with her husband, Cadence takes a moment to reflect on how lucky she is, and to assure Shining Armor of how great he is.

This story is a sequel to Families

Third in the Nuptialverse...

Twilight Sparkle has done much for Equestria. If it weren't for her, Equestria would be destroyed three times over by now.

So what happens when she has to leave? What happens when she and Spike are forced to depart from Equestria in order to fulfill their duties? And what happens when there's still important things at home to do?

Applejack, Rarity, Pinkie Pie, Fluttershy, and Rainbow Dash now have to get along without the one who leads them. All of Equestria is counting on them. Can they do it?

AU only post-season 2, since the basic idea for this fic was created long before it aired. Events similar to season 3 have happened, all of which will be revealed. Strongly recommended you read Post Nuptials and Families first.

Cover art by Concier

This story is a sequel to Post Nuptials

In the wake of her failed assault on Canterlot, Chrysalis is left stuck in the desert to brood on her failures. Angry and bitter, she reflects back on the events that led to her becoming the Changeling Queen.

Takes place in the same universe as Post Nuptials, though you don't have to read it first. I promise none of my other fics are going to be this dark.

Reading by Doctor Cobra!

Another reading by Plagen Shiki!

Another reading by Alchemystudent