When a supposedly-Forerunner artifact activates on-board the UNSC Guam, turning everyone on board into ponies, It sets in motion a clash of forces, ideals, and dimensions that could save humanity in its darkest hour, or doom the peaceful land of Equestria to burn in a war never meant for them.

This story starts some time before the season 2 finale, but after the other episodes of season two. Season 3 stuff will only be used if I find a reason for it/don't think it's OP (I'm looking at you Twilicorn and Mirror Pool.)
This story also takes place before Halo: Reach, so don't expect things to stick very close to the games.

Minimalistic cover art was made by me in Microsoft Paint, because I have buck-all else to work with.

Character tags will be added as they become major players.

Obligatory Disclaimer: My Little Pony Friendship is Magic is owned by Hasbro. Halo is owned by Microsoft (or some sub-company thereof). I have no stake in either and seek no profit from this work. This is purely a fan creation.

When the Elements of Harmony defeated Discord, they did their job too well, and completely undid all of the things Discord directly did...

... Like send a subcontinent from earth into a pocket dimension so he could focus properly on his toys. And now Equestria has appeared on Earth.

Yet, neither side was completely ignorant of the other. On Earth, there was the show "My Little Pony: Friendship is Magic" and in Equestria there was the ever popular movie serial "The Dark World: Technology is Courage" which was a favorite of colts everywhere as well as the "Pumans".

And now both sides learn through an event that the other is real. Come join us as we watch as both sides learn to work and live together. And as they find out that events on their respective fiction was not as nice as it seemed as we widen the lenses of the view points...

A Round Robin created on SpaceBattles of which I am a participant and am posting with all their permission.

When a human’s house crash lands on the outskirts of Ponyville, nopony is quite sure how to react to this strange creature. With seemingly no way to return home to his own world, one young man must adjust to this strange new world, and the world must adjust to him.

Starts between Fall Weather Friends and Suited for Success.

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.

My name is James Clark, and I am a Private Military Contractor. No, not Mercenary. Yes, there is a difference, but that's beside the point.

Ok, where was I? Ah yes, I was just entering my office in Downtown Houston one afternoon to hear a job offer. When I got there, I found a beautiful, robe-wearing woman waiting for me. Now, in this day and age, most people would find that strange. I didn't for two reasons.

1) In this line of work, you run into a few crazies. If I had a dollar for every nut-job I turned away, I could buy a small European country.

2) It was Halloween. Hell, I was on my way to a party dressed in a replica suit of Veteran Ranger Armor from Fallout: New Vegas, complete with gas mask and real riot gear I borrowed from a friend on the SWAT team. I was gonna win the costume contest for sure!

I'm getting off topic, aren't I? Anyways, this weirdo offered me a job without going into much detail. No location, no objective, not even a dollar amount The only thing I got out of her was the promise that I would be saving thousands, if not millions of lives.

Every instinct told me to turn the job down, and yet I still accepted it. Maybe the idea of playing hero again had its appeal.

God, I had no idea what I was getting myself into.

During the battle with the changelings, a trapped Discord manages an undirected spell that reaches across universes to bring an agent of chaos to Equestria. What's brought back more than qualifies.

Steam! Gears! SCIENCE! A very confused Spark! And, eventually, really good coffee.

Here comes Agatha Heterodyne--MARE GENIUS!

For the penguins - Skipper, Kowalski, Rico, and Private -this last day could have gone better. When testing Kowalski's Dimensionator (A device to find the user's ideal dimension) on Private, they found themselves warped not to the dimension of the Lunacorns (which would be bad enough), but in a dimension called "Equestria" which is full of pastel colors and female mammals. For the penguins, this would be bad enough, but they also lost their way to get home. And just because they can't get home, doesn't mean that other animals can come to them. Animals who's greatest desire is to destroy the penguins. At least the sudden cold snap is nice. (Note: this cross over is with the Penguins of Madagascar TV show which Word of God says exists in an Alternate Universe to the Madagascar movies.)

Reading an epic tale of one of the Third Hokage's missions, a 6 year old Naruto sets himself on getting some awesome summons of his own. Unable to find a contract on short notice, and not understanding why a contract is required, he goes through the necessary motions anyways and winds up in Equestria. Can Naruto convince the locals to let him be their summoner? Is the ninja world ready for the likes of Pinky Pie? Just how much will a young Naruto benefit from the Magic of Friendship?

Dainty Dish: The official record holder of the highest sustained speed and altitude over a recognized flight course in Equestria. As well as the holder of the time to climb record for a given altitude. There is no pony in Equestria who can match her abilities.

However, one stallion from from a far off place is determined to catch her. And in a brash attempt to prove himself worthy of her affection, gives chase. Only to fail spectacularly even with months of preparation. So on Hearth's Warming Day he enlists the help of Rainbow Dash, Equestria's foremost expert on speed to help him learn all there is to know about the art of going fast.

Can the mighty Mikoyan Ivanovich Gustaav the Thirty-First catch his dark angel? Or will he be too much stallion for Rainbow Dash- for Equestria to handle?

My name is Allen Fersch. My story begins on the last day of my life.
There’s a distinct possibility that every living being has a kind of “quantum immortality” that prevents it from experiencing its own death. At the instant when your body in one parallel universe dies, your consciousness jumps ship to the most similar parallel available where you did not die.
The truck swerved at the last second. The power went out. The gun jammed. You were thrown clear and you thank God the Almighty and all the saints and seraphim that you’re okay.
If you’ve ever been in a near-death situation where your life flashed before your eyes, there’s a good chance you’re not in your original body. That experience of “flashing before your eyes” is the download mechanism kicking in. In some lonely universe somewhere, all your friends and loved ones think you’re dead and your parents keep a picture of you on their mantelpiece, which depresses everyone when they come to visit for the holidays.
So what happens if the mechanism goes wrong? Like any natural process, there are quirks in the system. Some people are born with six toes. Some people have a defective downloader. If somebody you know ever had a near death experience and came out a completely different person, you’re seeing what happens when the escaping soul can’t match the parameters of their original universe closely enough. I shudder to think how many perfectly sane people are locked up in mental asylums because their soul skipped a track or two and now they’re living a timeline meant for someone else.
Sometimes you escape death and you never even realize how close you came, sometimes you escape it and the world around you is different in ways you can’t quite place.
And sometimes… you end up like me: completely off the grid.