"I have sworn upon the altar of God, eternal hostility against every form of tyranny over the mind of man."
-Thomas Jefferson

Three hundred years ago, Equestria tried to assimilate Earth.
They failed. They fled, rather than face justice.
We moved on. We conquered the stars, we made a civilization that spans across the infinite void. We built true harmony between species.
We thought we'd seen the last of Celestia, but as a desperate mobile colony on the fringes of known space came to discover, we were wrong.

It is time to finish what was started by our forefathers.

Based on TCB: Not Alone, by Starman Ghost.

EDIT: Following Starman Ghost's deleting of Not Alone, I've replaced the above link with one leading to a PDF file uploaded to mediafire.

EDIT (14/04/2014): The character of Evening Star was originally created by Starman Ghost. I am using her without his permission.

When Twilight Sparkle decides to try a new spell she has perfected, she successfully pulls a being from another universe into Equestria. That being coincidentally is a human...that human coincidentally is you. What at first just seems like an opportunity for first contact between two species soon becomes something much more when certain truths are brought to light...and everything you knew about your life is flipped onto its head.

NOTE: At times in this story, the main character's thought process will be shown as an inner monologue with his brain. BRAIN's dialogue will appear in this color of text.

The Princesses find an alien creature barely clinging to life at the scene of a terrifying crash. Can the Combined Power of the Elements of Harmony save it, or more importantly, should they save it? Will the arrival of this strange creature tear Equestria apart?

TV Tropes
https://tvtropes.org/pmwiki/pmwiki.php/FanFic/Article2

Princess Celestia: Goddess of the Sun, ruler of Equestria, beloved Princess of ponies. She is loved by all, and loves all in return. A calm and wise ruler, she sits on the throne in Canterlot, maintaining peace and harmony throughout the land.

What most don't know is that her past is much darker: She was once a commander of legions, a warrior and scientist of unmatched skill. Thousands of monsters and abominations fell to her forces, slain in the name of an old leader, one entombed within his own throne. Free of her old form, free of the powers of Chaos, she was cast into a new realm, in a new form, with a new lease on life.

She is the God Emperor, Eternal Ruler of Equestria and Lord of the Imperium of Man.

Has a TvTropes Page. Please contribute.

Comments contain spoilers. YOU HAVE BEEN WARNED!!!

Twilight Sparkle presents a collection of interviews, letters, essays, poetry and prose compiled over several years of her relationship with the human Bellerophon and his "herd", covering subjects as broad as Equestrian social taboos, comparisons of earth and Equestrian mythology, romance and the occasional recipe. Compiled by Twilight Sparkle, with foreword by Her Royal Highness, Princess Celestia.

(This is a bit of an experiment based on the worldbuilding concepts presented in AnonAuthor's Xenophilia [[NSFW] - caveat lector!], which intrigued me enough to want to take a closer look. It's likely you'll be very confused by this unless you read at least some of Xenophilia. Updates will appear as and when an idea pops into my head for a thing to add. And fair warning, some of this might come across very dry and dusty. Thank you academia! And thank you AnonAuthor for letting me have a go, and both AnonAuthor and AnonponyDASHIE for all the collab work they're doing. I'll make up for the dust by tossing in the odd piece of art now and then.)

The year is 2154, Humanity is on the cusp of interstellar travel, with the earth united under a single banner. Then an anomaly is detected, 0.75 light years from the sun a Wormhole has formed, large enough to swallow a planet and stable enough to stay open for years at a time, in a rush of scientific progress a vessel is built and crewed with the cream of humanity, the best astronauts from around the solar system.
Then it sets out across the stars, a physics defying engine driving the ship towards this gateway to places and times unknown.

A universe away, a purple coated unicorn trains her telescopes to the night sky, and notices a strange object in the sky. A hole in the endless dark between stars, through which another dimension can be seen.

Equestria has made the discovery of the century. They found what they believed to be the last of the mythical race of the humans trapped inside of a large crystal. Curiosity takes hold and with the help of Twilight Sparkle and the elements of harmony they decide to set it free. But was that a wise decision?

Cover art not done by me.

This story is a sequel to Of Solicitude

Ten years after a massive war, Equestria has changed. The Empire now rules over all, giving peace and prosperity to those that deserve it, but some are against this new rulership.
The CMC, a small, raggedy group of smugglers working for the Apple family, are caught red-hoofed by an Imperial patrol. As the friends fight for their lives, they learn about themselves, each other, and the world they now reside in.
Meanwhile, in Canterlot, Emperor Blueblood has amassed a massive fleet and is preparing to smash what is left of the rebellion under the oppressive hoof of his Empire.

Fantart:

http://www.youtube.com/watch?v=cSqZZHhQa_I

http://www.youtube.com/watch?v=JE7m2dk8FB4&list=UUS5YHp6kB61DHIXt8THr4iQ&index=1&feature=plcp

Beyond Earth and beyond the Universe within which Earth exists there is a place full of love; the richest mine of love that can be found, as it is seen by those capable of utilizing it...

Within that place, specifically a part of it called the Everfree Forest, awakes one such creature: a Changeling; specifically, a Changeling who had been a human on Earth the day before. How will he survive in a body that literally needs love for nourishment, while in a world that is now wise to the Changelings' tricks and has branded them evil? Better question: Will he be able to change more than his physical appearance?

These questions are not the only thing that will plague him, for the hows and whys of his arrival and transformation are in a hurry to reveal themselves, and Equestria's heart will stop as it waits for its fate to be decided.

Now with a side story (with more to come) from other characters' POV!
POV: MANE SIX

I'm a spiteful old man. I've spent my entire life trying to fulfill my wish. The same thing every one of us wants.

The year is 2070. I'm the last brony alive, 82 years old. But I did it. I created the portal. And I'm jumping through. No regrets.

I've actually finished writing this story! Can you believe it? It's also available in book form, Click Here to go to lulu.com