Equus, the world, has a long and rich history, starting with the beginning of the first writing civilization dating many tens of tousand of years back, but before that?
Many believe that life simply kept evolving from one form to the next until the present species appeared, others believe that some deity had at least a part in the creation of the world, and very few others suspect that the truth lies in something far more incredible than any myth, something tied to a single word.
Humans.

The age of chaos has come to an end. The Avatar of Chaos, Discord, has been defeated by the valiant actions of the newly-minted alicorn sisters. Their courageous victory has earned them the adoration of their hometown of Evergreen, and they now seek to unite all of ponykind under their banner.

In the disconnected world left in the wake of Discord's reign however, theirs is not the only story to be told. Not all of them even start in their world, for that matter.

Geralt is a unassuming man living a comfortable but mundane existence. While not dissatisfied with his own life, he has always dreamed of what it would be like to make more of himself. To be able to live a life of adventure and glory, to steer the wheels of history.

Fate has smiled upon on him and granted him the opportunity to do so when he is swept away by a chaotic winter storm across worlds, finding himself in a new feathery body. He soon finds himself taking the first steps and rising above anywhere he thought he could reach as he defends his new home, and begins to build a shining beacon of prosperity that will resound throughout the ages.

But victory comes only to the prepared, and the road to his dreams will be long and hard. It is world filled with all manner of mysteries, monsters, and rivalries. A world where a land is kept safe by the armies that it fields. And so Geralt will resolve to stand tall, to defend his lands and his people, and to see his banner flying forevermore.

Centuries ago, the younger sibling of the Solar Princess was sealed away. What followed that was the disastrous rebellion of the young sister's soldiers. Once the rebellion was crushed along with the Lunar Branch of the diarchy a period of harmony begun... or at least that was what was said. During this period, an "Incident" happened that nearly caused the collapse of the Solar Monarchy. An event that was "lost" to history. Centuries later, after the resealing of Discord; Princess Celestia summoned Twilight Sparkle for a secret mission.

"Twilight Sparkle, please help the Lunar Captain make some friends."

A journey regarding the hidden dark past of Equestria waits for the young hero.

An accident in the lab sends our favorite boy genius to Equestria, as a pony. What will he do and how will he get back? The answer: Science! (Cover Art Updated!)
New FAQ! and TV Tropes!
Planned Phrases from Dexter:
“Pinkie Pie! Don’t push that Button!” /to Pinkie
“Please, Magic is the word simpletons and the ignorant use to describe what they cannot understand.”/ to Twilight
“No, I didn't strap a rocket to you. I strapped you to a rocket.” /to Rainbow Dash
“Friends? Who needs friends?”

Dexter is a boy super-genius with a disdain for anything girlish and no desire for friendship. After an mishap in his lab, he gets stuck in Equestria. How will he cope with the over-friendly ponies, and the girlish everything?
For any who do not know Dexter's Lab: http://en.wikipedia.org/wiki/Dexter's_Laboratory
[RIP Christine Cavanaugh: 8/16/63-12/22/2014] - Dexter's Original Voice Actress

Formal Premise: The inventors of the Mirror wanted to create a device that could channel infinite magic and grant wishes. The hard part was making sure those wishes would never destroy the world. Showing a person their heart's desire is a sensible precaution to put into a wish-granting machine designed NOT to go horribly wrong.

The Atlanteans got close, even managing to imbue some amount of intelligence and morality into the Mirror. But they never finished their work; the Mirror never DID get to the point where it could grant wishes... at least, nobody believes it ever got to that point. But then, nobody has ever been trapped inside the Mirror and returned to tell the tale.

When the Mirror traps someone inside itself and outside of Time, that person and their consequences can no longer affect the world. In that circumstance, with a person fully under its power, the Mirror isn't limited in what it can do. Sometimes, it can even grant seemingly incompatible wishes.

But complex problems require complex solutions. In this case, the Mirror takes a few massive liberties about how, exactly, it satisfies the wishes of both Harry Potter and Lord Voldemort. Namely, it sends them to a world of ponies.

Informal Premise: This is a crossover between MLP and Harry Potter and the Methods of Rationality, not just Harry Potter. No matter how accessible I try to make it to those who haven't read HPMoR, those who HAVE read it will undeniably have an easier experience reading this story.

HPMoR is the second most popular fanfiction of Harry Potter, at least according to fanfiction stats. It involves Harry studying & dissecting the wizarding world with science. Not with technology, with actual science. That is, he uses the experimental method, generates and tests hypotheses, and in the words of his Occlumency instructor, "wants to discover the underlying rules of magic to become all-poweful".

THIS fanfic brings THAT version of Harry Potter to Equestria. It also brings that story's version of Voldemort.

If you want the best reading experience, please go read HPMoR first. It can be found on fanfiction dot net, or on its own website, or even on any podcast app, as it has its own fan-made audiobook with 30+ contributing voice actors, production quality, sound effects, music, etc. (which is more than can be said for most PROFESSIONAL audiobooks).

Link to HPMoR on fanfiction: https://www.fanfiction.net/s/5782108/1/Harry-Potter-and-the-Methods-of-Rationality
Link to HPMoR on its own website: http://www.hpmor.com/chapter/1
Link to audiobook (though the website isn't nearly as good as podcast apps): https://hpmorpodcast.com/?page_id=56

All forms of HPMoR that I've encountered are high quality, but that doesn't mean it's for everyone. You can probably read the first few chapters of HPMoR in thirty minutes or so. If it doesn't appeal to you, this story probably won't appeal to you either.

For those who haven't read Methods and want to read this story anyway, the first two chapters are going to be the most confusing. They're mostly housekeeping and stage-setting, barely touching the MLP universe beyond the new setting.

And I think the same advice Yudkowsky gave for HPMoR applies here. The story starts hitting its strides around Chapter 5, if not sooner. If you don't like it by Chapter 10, best just to give up and read something else.

In Manehattan there is a strange ape-like creature that is being held in a lab. Its injuries bear the distinctive marks of illegal sport hunting by exotic game poachers.

What's strange is that there's an entire section in books on natural life about this creature designating its kind maned apes. What's even stranger is that there are accounts throughout Equestria's history about maned apes turning up.

The maned ape, given the moniker Big Red by the scientists holding it, is given over to the crown and transferred to Ponyville for safe keeping. The Mane 6 comb through Equestria's historical texts and oral account to try and find where the maned apes come from.

This is an HiE story that starts in Season 1 shortly after Apple Buck Season.

EDIT: 6-8-2022 Featured! Woo-hoo!
18-202023 Featured! Woo-hoo!

A machine made for war awakes in a new world. Stuck in surroundings which puzzle it; can it, or will it be able to become something more than what it is?

Crossover with Keith Laumers Bolo-verse
Other tags include : Slice of Life, Possible Romance believe it or not! And a bit of humor.
Please beware of any spoilers in comments as well