Twilight Sparkle broke time when she got her cutie mark. Now Twilight and Sparkle are sisters from another time. Twilight is hailed as the potentially greatest light magician of all time, and already has a reputation as a hero by the time she goes to Ponyville. This isn't her story, not primarily.

Sparkle is an orphan - her dark magic killed her parents. She lives with her brother in Canterlot's industrial sector because they can't afford anything better. She can't leave either. She's a natural dark mage; while Sparkle won't go mad like Sombra, her reputation is hardly any better. Worse, the law doesn't see her as a good pony.

The fact that the dead don't stay dead around her, or that Thorn - Spike's double - is an undead, soul-eating abomination, are other matters altogether.

(Also has some Slice-of-Life, but fimfiction tags won't let me put it with Adventure.)

Has an ask blog to go with it: Ask Sparkle and Thorn.
Also has a TvTropes page: Split Second Tropes.

Featured on EQD.

Cover art by Swirling Line.

[Complete! With TVTropes apparently!]
Also, apparently, an animated trailer.

In a world of brass and steam, Twilight Sparkle had thought she had made a life-changing discovery with the invention of the telescope. For better or worse, she was correct.

Now her discovery has not only changed her life, but the lives of those she seeks out in her desperate attempt to contact the only other creature as lonely as Twilight herself.

It all would have been much simpler, but it had to be the one Twilight could only call The Mare on the Moon.

Decidedly not within walking distance, then.

[Featured on EQD before story was meant to be submitted. 4/03/2015]

[Editing team: Southpaw, Wolfvenom, Maskedferret, SwanSong and BluePaladin42, without whom this story would be a fraction of its current state.]
[Special thanks to Novel-Idea for the updated cover]

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.

A flip of a coin. A twist of fate.

Twilight Sparkle, younger sister of Princess Celestia's personal student, Shining Armor, grew up listening to her brother's bygone dreams of joining the elite of the elite: The Royal Guard.

Now, fresh out of the Academy, this young mare is ready to prove herself equal to the deeds of the great soldiers she read about as a filly. Too bad the princess she ends up protecting isn't Celestia.

This story is a sequel to Twilight Sparkle of the Royal Guard

Between castle gossip, professional rivalries, a blooming romance, and a mysterious malefactor still at large, Decurion Twilight Sparkle has a lot on her plate. Hopefully, she'll make a few new friends as she moves towards the destiny she's chosen for herself.

As per usual, big thanks to Magello for the rad cover art!

Twilight Sparkle comes across a small, battered diary detailing a new form of transportation. While the research is sloppy and the notes incomplete, Twilight takes it upon herself to see that the ancient project is completed.

Of course, nopony said it would be easy.

The princesses gave their magic to Twilight to prevent Tirek from stealing it. As a result, they end up stuck in Tartarus.

Marvelous place, Tartarus. Really brings ponies together. The fact that things manage to go downhill here says a lot about the wonders of family and alicornhood.

Spanish translation by SPANIARD KIWI

Audio Drama by Espa_Roba_5 and Ajvasquezbrony28
Live reading by The Living Library
Live reading by Astro-Brony

Proofread by Octavia Harmony

Twilight becomes alicorn of the stars. This is sort of a problem, because Luna kind of already was alicorn of the stars. Oops!

TV Tropes

AU. Based on the first season. Twilight and Celestia begin to drift apart due to a misunderstanding. Will Luna speak up and repair the breach, or will she remain silent to keep her new friend, Twilight, all to herself? What other challenges will face everypony involved because of this new relationship?

It's a simple little love story. Unfortunately, love's not simple.

Twilight did her duty. She saved everypony she could, except herself. Now trapped by an evil cult, in more pain than she has even been in before, and dying on a sacrificial altar, she calls for help. The Nightmare answers.

Will Twilight become the next evil to threaten the world or will the Nightmare simply be glad to have some freedom? One thing is for certain, Twilight's life will never be the same again.

The Editors
Cander (CH 1-Current)
Yutah123 (CH 8-9)

Now with an excellent reading by StraightToThePointStudio (Currently only up to CH 30)

And we even have art!
[Warning Spoilers] Twilight's Nightmare Art