Inexperience is a foreign concept to Celestia. At least she thinks it is. Right up until the moment a rash decision leaves her with a student who is a dozen years younger than what she's used to.

Enjoy.

In an Equestria where Discord never was, and the Pony Princesses never came to power, a young Twilight Sparkle loses her family in a crowd during the Summer Sun Celebration. Little does she know that her very existence is about to set a series of events into motion that will take her far beyond the borders of Equestria itself—and change the fates of both her nation and her life, forever.

On secret assignment from Princess Celestia herself, Twilight investigates a powerful magical artifact for clues to the mystery of Luna's transformation in the evil Nightmare Moon. Incautious use of the artifact sends Twilight hurtling back in time. Can Twilight discover what caused Luna's transformation? And will she ever make it home again?

Kickass cover art used with permission from Bitz.
http://allthebitz.tumblr.com/

This is the story of the end. This is the story of the death of Equestria. It is the story of the reign of her royal majesty, Princess Twilight Sparkle of the Fading Sun.

The alicorn sisters are dead and Equestria has turned to Twilight Sparkle to guide it. However, just maintaining a dim sun a fraction as bright as her mentor's keeps the new princess near her limits.

Years have passed and Twilight Sparkle is sure of only one thing. Equestria is dying.

NOTE: Written before "It's about Time" in season 2. Everything after "Read it and Weep" was ignored throughout this story.

For almost a thousand years, the immortal Nightmare Moon has reigned over Equestria as Empress. To the average pony, Nightmare Moon is an overarching enigma whose rule is absolute and whose wrath is terrible. But to Twilight Sparkle, who as an orphan has never known her parents, the Empress is something else entirely. When the young unicorn is brought under the royal wing as an apprentice, she learns a great deal more about the supposed tyrant than she ever knew. But as Twilight is introduced to life with her new mentor, she is thrust into a world of political intrigue, conspiracies and secrets. Secrets that were never meant to be revealed. As allies and enemies plot against the very peace of the nation, will Twilight fall prey to the perils of her new position? Or will she prosper and find in Nightmare Moon the mother she never had?

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My eternal gratitude to my editor, LordOfTheWrongs, without whom Night's Favoured Child would not be the story it is today.

Now with added TVtropes!

A diplomatic crisis arises between Equestria and the small, poor kingdom of Tarandroland, ancestral home of the reindeer. Celestia and Luna agree that it is time Luna takes a more active hand in foreign relations again, and Luna brings Twilight with her as someone she actually trusts and can talk to. But the mission turns out to be much more than political discussions - if scheming unicorn courtiers, unfriendly surly reindeer, bloodthirsty pirates, ancient sorcery and dangerous monsters weren't enough, our heroines must deal with something old - older than Luna. And is Luna really ready for diplomatic action, will Twilight learn to use a fan properly, and exactly how wrong are Spike's superhero comics about reindeer mythology?

Now has a TV tropes page

For as long as ponies can remember, it has always been winter. With limited resources and worsening weather, war is escalating, driving them closer to extinction with each passing day. Hidden away in the middle of all this is a single purple unicorn who braves the frozen wasteland, looking for a way to stop the weather and return the mythical sun to the sky. However, in a world without harmony, the task is far greater than she could ever know.

Edited by DoomManta

We all know the story of how the Princess’ young student and five friends defeated Nightmare Moon and brought Princess Luna back to our lands. But what if the tale were false? What if the young Twilight Sparkle on the event of her entrance exam had not been rescued by Princess Celestia, but instead lost her mind among the power of her youthful surge and had to be sent away, far away before she could destroy all of Canterlot with her newfound power. Now the feral unicorn prowling the Everfree Forest only vaguely remembers her past, slipping away from constant terrifying attempts to capture her.

And she is beginning to remember what true power felt like.

Editors include: Peter, Justin, Featherprop, Mitch H, and Bad Horse
Featured on Equestria Daily
Reviewed by Chris on One Man's Pony Ramblings and by Paul Asaran on his review blog
Now with a TV Tropes page

Physical books are available on Lulu.com
Monster in the Twilight (Paperback) 272 pages
Monster in the Twilight (Hardback)