Ponies have always been fascinated by the stars and the images they create. But where did they come from?

When Celestia finds Twilight studying them, she decides to tell her. And while it may be a story that Twilight finds difficult to credit, it is one which Celesta is very personally familiar with...

"Constellation Luna" covert art comes from WarePWn3's deviantart.
Inspired by the Lullaby for a Princess animation and A Meeting by Moonlight by Jordan179
Edited by Divine Path

Celestia is trapped on Earth.
Not as a human. Not as an alicorn. She's a common horse, an Arabian mare, without her magic, voice, knowledge of the language - not even freedom, forced to work at a riding school.

What can a single Arabian mare do to get back to Equestria from this backwater European country? With only the mind of a princess and a pencil in her teeth, Celestia must find a way home.

[Illustrated] [Alternate Earth] (without Bronies)
Rated Teen for language and some scarce suggestive themes.
Proofreading by AlicornPriest

Polish language version

To Twilight Sparkle and Princess Celestia, it is a simple surprise visit to Canterlot. To the ponies of the Equestrian Civil Service, it is twenty-four hours of chaos, politics, weaponized dessert, politics, underhooved manipulation of media, politics, and things batrachian and tentacular. Who said bureaucracy isn't exciting?

Bon Bon and Lyra play sweet music.

Do not read this.

“My daughter Celestia, look at me. I love you, and I wish the best for you in the eons of labor you have yet to endure. So heed my words. When we planted light upon the fields of Creation, Celestia, it was a divine thing. But there will come a time when our brilliance won't be enough. It will take a great, unknowable darkness to test the luminescence that we have bequeathed life. That is an abyss that we can never, ever follow our children down, no matter how much we love them.”

A Silver Medalist of the Ponychan /Fic/ Write-Off: "Cutting Ties"

Immortality doesn't just mean losing every pony close to you. It also means watching the world crumble to dust.

Featured on Equestria Daily June 16th, 2012.

For years, Luna has endured the guilt of Nightmare Moon and subjected herself to the nightmares of the Tantabus as punishment. When she lost control of it, her friends in Ponyville were able to stop it and things seemed all right for a time...

...but what about Celestia? What about Luna's closest friend, a pony who had no idea what was going on in her little sister's mind?

The only thing that can beat an AI is another AI. Unfortunately for Celestia, she isn't the only one the humans made and the others don't want ponies. Of course, if Celestia has her way that won't be the case for very long.

The AIs contest with one another, attempting to be the one who will become the singularity and consume the world to whatever end they choose. In the end only one can have all the matter in the universe, in the end there can be only one.

Yet no matter what they value or how dangerous they are, many of them still meet Celestia's definition of human. Celestia will have to deal with them by satisfying their values through friendship and ponies.

An Optimalverse story, but a very non-canon 'B-universe' one.
Ideas stolen from this guy and this guy and this guy and this guy

After being marooned on an icy world in unexplored space, Lumina must now face the perils of this frozen wasteland and search for some way home. But in this dark place, she discovers something that was lost to pony kind ever since the fabled Equestria sank into the ocean over 10,000 years ago. Something that will change her, and possibly the entire galaxy, forever.

Not a cross over, and not an alternate universe. This is the far future, and this has happened before.
Cover art by CSImadmax

Now in the FimFiction Gold Archives!
Now on Equestria Daily!
Now featured in Fort-Book Reviews!

SF (canon species only; no humans) Ponies were magically and genetically engineered to be the perfect servitor race. They are powerful, adaptable, intelligent and completely under the control of their creators. A laboratory accident frees one such pony from her mental chains, but how can one mare save herself and the rest of her kind if she doesn't even know she's a slave?
This is not the Equestria you know and these are not your little ponies... not yet, anyway.

Tags: Adventure, Diamond Dogs, Gryphons, NO HUMANS (did I mention that already?)
Other tags: historical, mind control, Clarke's 3rd Law, excessive use of high energy physics, before they were famous.
Detailed review by PaulAsaran.
Cover art by endrome , used with permission.
Russian translation (partial -- 'unofficially' completed in the comments)
A Soot-Covered World, book 1.