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

Going up to the roof for some fresh air after pulling and all-nighter, our "hero" makes the mistake of closing his eyes for a bit.
When he opens them again, he is no longer on the rooftop in Copenhagen he was expecting to be on... no he's somewhere very different, and extremely unfamiliar.
How will he react? How will the ponies react? Nothing is certain, except for one thing...

He never asked for this.

This story takes place about 8'ish years after the second season of MLP:FiM, the language of Equestria does not match any earth languages (that the main character knows of at least), and the human in question knows nothing of these ponies or the world of Equestria.
He emerges into Equestria on the roof of a building in Manehattan, not the Everfree, not Ponyville and certainly not one of the princesses' bedrooms in Canterlot Castle.

Oh! Spoilers in the comments and all that jazz, not gonna go into a whole spiel about it.

Twilight ventures out into the mountains to see a once-in-a-lifetime event. Disappointed by her friends not coming with her, Twilight crosses paths with a kindred spirit.

Humans.

Truth or myth? Ancient lost civilization or just an old pony's tale?

No pony has ever seen one, and most haven't even heard of them. But Lyra knows that these wonderful creatures are more than just old legends, and she's going to find out... and possibly drive her roommate insane in the process.

...My name is Alex Mercer. I'm the reason for all of this. They call me a killer, a monster, a terrorist... I'm all of these things. Three weeks ago someone released a lethal virus in Penn Station. I woke up at the morgue. Now I hunt, I kill, I consume, I become. I'm gonna find out who did this to me... And I'm gonna make them pay.

Finding herself with wings and unusually powerful magic, Twilight Sparkle proceeds to have breakdown after breakdown, until with the help of her friends, she confronts Celestia and Luna about it... And learns that she's a far more important little pony than she ever imagined - for all the wrong reasons.

Awesome painting by Drezzer can be found here!

20 megapixel version is here (10MB JPEG, 210dpi strangely, 24"x20")!

Thanks, man!

Twilight Sparkle is called away to tend to Luna when she falls ill. As Luna grows sicker and Twilight more determined to help the younger princess, she begins to uncover dark secrets about the elements, the alicorns, and her own past.

The earth spun through space. Basking in the light of the sun on one side, and of the moon on the other. The eternal dance playing out as it had for untold years. The sun roaring and bright, the moon cold and aloof, while the earth sat in between, bustling with life and growth. Below on the expansive surface of the world, in a country, in a village, in a house by the forest a yellow pegasus walked out the door to check on her animals. She was not particularly brash, nor brave, or all that strong of will. And the day was not of particular importance. Still, on that unimportant day, the unassuming pony would uncover a long held secret.

Comments and stars appreciated.

It's springtime in Equestria and Twilight Sparkle and Princess Celestia find themselves out of sorts despite the gorgeous weather. Luna and Rarity both think they know the reason behind their moodiness and set out to make sure that true love blossoms - but will an unfortunate misunderstanding keep the two star-crossed lovers apart forever?

Illustration courtesy of nightmaremoonluna, adapted from a sketch by bri-sta.

After the disastrous invasion of Canterlot, an injured changeling wakes up near a small cottage and is quickly discovered by two of the last ponies she ever wanted to see. Now, with the help of her new "friends," she has to remain undetected in a town high on changeling hysteria that would not hesitate to throw her in the Canterlot dungeons should her true nature be revealed.

Simple, right?

Too bad she couldn't have picked a worse form to stay inconspicuous...

Many thanks to ZuTheSkunk for the cover image!