This story is a sequel to Stardust

Everyone knows the story of Hearths Warming Eve. They know the tales of the three pony tribes and how their strife brought the Windigoes upon them, and how the Fires of Friendship saved them from their frozen fates. For countless generations the tale has been told, but how has it changed over those years?

Or is any of it true in the first place?

Only one pony knows, and Celestia would prefer that the past stay forgotten.

(Based on a 'What If' line of thought that was born from the Stardust storyline. While some familiarity with Stardust and Mente Materia doesn't hurt, this story can be enjoyed on its own)
(Coverart available soon from the amazing FoxInShadow!)
(Many thanks to Arzoo, BradTheBrony, Vandenbz, and Setokaiva for prereading!)
(Complete with it's own TVTropes page as part of the Stardust continuity)
(Character tags will be added as chapters are added!)
(Possible spoilers in the comments! BEWARE!)

This story is a sequel to Stardust

Times are changing for Equestria as Twilight’s return brings with it news of people and cultures from beyond the peaceful world everypony knows. Aid and volunteers are freely offered to help the besieged humans of Earth because every Equestrian knows that’s what good friends do. Unfortunately, making friends can also have the unintended consequence of making enemies.

When the monsters besieging the humans strike at Equestria with a level of brutality not seen in over a thousand years, the cry for help is sent to all the kingdoms of the world. Honored allies step forth to fulfill ancient treaties and oaths. Enemies, old and new, bury their grievances. An alliance never before seen in Equestria will be created to combat the monsters from the void.

And because of these events, a grim but welcome sibling to the XCOM project is born.

(XCOM/FiM Crossover)
(Sequel to Stardust, which I recommend reading before starting this. Fortitude Amicitia and Broken aren't required reading but are supplemental to the storyline)
(Gore tag for blood and violence)
(Alternate Universe tag because of the divergence from canon that Stardust has caused)
(Uses elements of Season 4)
(Coverart produced by the amazing Carnelian!)
(Many thanks to Arzoo, BradTheBrony, Vandenbz and Setokaiva for prereading!)
(As of 03/07/2016, the prereading team consists of Arzoo, BradTheBrony, Noble Cause and Metallusionsismagic!)
(Complete with it's own TVTropes page as part of the Stardust continuity. Could use some updating!)
(Character tags will be added as chapters are added!)
(Featured 5/12/2014! Thanks folks!)
(Possible spoilers in the comments! BEWARE!)

Isolated from her friends and taken prisoner in the middle of a war, Twilight must deal with the very real dangers of being percieved as an enemy as well as the nightmares of her arrival on 'Earth'. Can she overcome her own fears and the fears of her captors? Will the wayward unicorn's assistance be a boon or a curse to the 'humans?' Most importantly, will she ever find her way home?

"In short, it's a story of friendship and plasma rifles, with the emphasis on the friendship. The characters are well written, the XCOM setting is fleshed out very well, and the story is compelling. If you love XCOM, you'll love the story, but even if you've never heard of it, it's more than worth giving the first 3 chapters a read.

There's excellent action later on, but the real strength lies in the collision between the friendly and naive world of Twilight Sparkle and the desperate world of humans fighting a losing war for survival and willing to do anything to turn the tide."

--Arzoo

(XCOM/FiM crossover)
(Cover art commissioned by a friend and created by the magnificent FoxInShadow!)
(Original cover art by the amazing Carnelian can be viewed here!)
(Gore tag for blood and some violence)
(Many thanks to the studius OminousTen, Arzoo, xXFluttershyForeverXx and finally Setokaiva for giving my rambles a once-over)
(Now with it's own TV Tropes page! Get to tropin' folks!)

Twilight Sparkle has too much magic, and it will take her decades to learn to control it. Her spectacular loss of control during her entrance exam only proves that fact. She is a danger to herself and others.

After Sunset Shimmer’s disappearance, Princess Celestia needs a new student to bear The Element of Magic to defeat Nightmare Moon. With all of Equestria at stake, Twilight Sparkle…is not the pony she needs.

Princess Celestia seals Twilight Sparkle’s magic with the distant promise of one day teaching her.

But there are two diarchs of Equestria. Amidst a lucid dream, an offer is made.

“Hello, Twilight. Would you like to be my student?”

Cover art provided by Lafiir.

Bon Bon's voice is funny, and that's about all that anypony who meets her notices, as her marefriend Lyra soon steals the spotlight with her explosive personality, strange obsessions, and curious beliefs. And why not? Bon Bon is, after all, a perfectly ordinary, boring pony in every way but two: her voice, and the carefully kept secret that she isn't really a pony.

(Edit:) Now with an annotated version, courtesy of the incomparable Shoggoth Lord!

When Fluttershy received her certification as a fog specialist, she only wanted a plausible excuse to write off the expenses associated with her ground-based house on her taxes. However, when an accident in Cloudsdale sends a blanket of industrial-grade clouds rolling towards Ponyville, Fluttershy suddenly finds herself in charge of coordinating the response, mostly because she's the only fog specialist in the area. Can our heroine step up to the challenge at hoof, or will she risk facing the wrath of the Equestrian Revenue Service?

Artwork by Page Turner. Now with a TVTropes page!

Be Awed and Amazed by the tale of Sweetie Belle as she traverses the multiverse in search of her lost mentor and friend, Twilight Sparkle! Will she find her in post-apocalyptic Equestria? Or maybe in a strange world where everypony is the wrong gender? Or even where a Pony claims to be a human? Read as she journeys through very familiar worlds you might have read about... if you dare!

At this point in time all the main worlds to be visited have already been chosen. Thank you all for the suggestions, and I hope you enjoy the surprises!

Here's the official TSC:F Music Intro: The Sweetie Chronicles: Fragments

WDTP: S2/3-CE
You can also visit the TV Tropes Page which has spoilers!

When Twilight Sparkle slipped beneath the covers last night, everything had been fine. She had friends whom she loved, a teacher she adored, and a bright future ahead of her. But when she woke up, her blankets and quilts had been replaced by hospital gowns and padded restraints.

Everything is wrong and nothing makes sense; even her friends have changed. The doctors keep telling her that she is sick, that none of it was real and that it was all in her head. Yet she remembers a life far beyond the hospital walls. She couldn't have made it all up on her own. They must be lying… right?

Ask Asylum Twilight - Still updating regularly!
Equestria Daily
TVTropes
Asylum Fan Group
The Tartarus Project
Russian Translation
The Asylum 20,000 View Spectacular Stage Show!

Art:
Asylum Cover by conicer
Twilight and Twilight Smiles by dreamingnoctis
Mirror Twilight and Plague Doctor by Jaestring / BloodGoldWings
Twilight Smiles and Doctor AJ by conicer
Nurse Ratchet and Silas and What's in the mirror? by Archonix
Doctor AJ Sketch by Archonix | Colored and vectored version by ReFro82
Twilight's Asylum by Khan the Cake Lover
Smilight by HappySwitch
Twilight Waking Up by Dombrus
Fan Art by toxicdemon10
Asylum Twilight by Madness-With-Reason
Asylum Fluttershy and Asylum Ch 26 by Downburst-Backspace
Twilight and her Twin by v747
Birdgirl by sirValter

Readings and Videos:
Asylum Animated Trailer Video by formuladash
Reading by Gammarobot (SugarCubeRadio): All Chapters Here
Reading by Ender Brony: All Chapters Here
Reading by VisualPony: All Chapters Here
Reading by MelancholyIguana: All Chapters Here
Fan Trailer by Kaidan: Asylum FanFic Trailer Cuckoo's Nest

Sanctuary by Kaidan
Broadhoof Files: Dr. Humors by TypewriterError
Broadhoof Files: Corporal Phalanx Spear (Ret.) by Phalanx Spear
A Hearth's Warming Tragedy by Seven Fates

A special thanks to Breath of Plagues, Rex Ivan,
ChudoJogurt, Cynewulf, Death the Kid, Selbi, PrinceDolph, Blahman2816, Queue, and Gage!

Axan Zenith - Dr. Dreamer
Dratini4 - Way Finder
psychicscubadiver - Bright Mind
Velkaden - Dream Chaser
Reese - Silver Glow
Viola Heartstrings - Clover
Archonix - Spinney Whiteacre

It's just another day of weather bucking for Stormy Skies. Nothing special, as usual. Then, like a bolt out of the blue, everything changes and nothing is the same again. Now she finds herself accused for crimes she didn't commit and threatened by unknown assailants. But can she trust the mysterious mare, Misty Morning, or is she a part of the plot as well?

(Edited by Icy Shake)

A horrible Cataclysm has turned all of Equestria into a Wasteland of barren ash and twilight desolation. The Sun and the Moon have been destroyed. Everypony has died--including Princesses Luna and Celestia. But one pony miraculously survives; she is a lone wanderer, the last of her kind, surrounded by menacing creatures that hate her. She navigates the Wastes in an airship and scavenges off the blighted landscape to keep herself alive.

Then one day she meets an old companion who grants her a gift, the chance to go back in time to the warm and sunny days of Ponyville, where her dead friends live in happiness. How far will the last pony venture into this joyous age of Equestria, even if she fully knows that there is no way to change the horrible fate of everypony she loves?

2013 Edition: Smaller Chapters, Better Grammar, and a Few New Scenes

(A shout-out to Vimbert, pre-reader and gentlecolt)