Caramel wasn't always a Changeling, but he's going to become one. And he's going to do it for the sake of his very special somepony.

Robert Parker is a 24 year old ex-web developer living in New York city. In the wake of the conversion movement, he has seemingly lost everything. Haunted by the same nightmare every night, he soon realizes that he must make a choice.

To those unfamiliar with the Conversion Bureau: it is a scenario created by an author named blaze in which Ponies either appear in the human world or have lived beside humans without incident for millennia. One day, in the face of all the damage humanity has done to its world, the ponies offer a solution: undergo conversion to become a pony and allow the world to be inundated with Equestria's influence: thus healing it and bring forth a golden age.

Many different authors have taken many different approaches to this idea, all of them are worth checking out.

http://www.ponychan.net/chan/fic/res/53616.html (The current thread)
http://www.equestriadaily.com/2011/04/conversion-bureau-compilation.html (The compilation post on EQDaily. *NOT UPDATED*)

When your life is as dull a gray as the world that surrounds you, the mundanities can make it all seem meaningless. Sometimes all we need is a little color -- or six -- to reintroduce us to what truly makes life worth living.

*6-16-2017 Edit, added Rainbow Dash tag because it triggered knighty.*

On a dark night filled with even darker magics, an insane cult attempts to give Nightmare Moon a body and life of her own, utterly separate from Princess Luna. But, when the spell is interrupted by Celestia, something unexpected is created.

Now, a little black alicorn filly named Nyx finds herself living under the care of Twilight Sparkle, only to be haunted by memories and emotions from her past. Is she Nightmare Moon reborn or is she simply a doppelganger with a soul and mind of her own? Can Twilight Sparkle protect Nyx from those who refuse to see past her dragon eyes and black coat?

Or, will Nyx be forced to inherit the sins that may not even be hers and become the greatest evil Equestria has ever known?

While on deployment to the Arabian Sea, the crew of a Royal Australian Navy Destroyer begin to notice that one of their helicopter pilots is starting to develop some rather odd quirks, both mentally and physically.
A cutie mark, wings, hooves, and a knack for treasure-hunting, just to name a few...

A recursive fic to TwistedSpectrum's "Five Score, Divided By Four".

Art made by the talented F-NAR.

Inspired by Twisted Spectrum's Five Score, Divided By Four, a story that has become the most recently popular Human to Pony Transformation fan fiction on /mlp/

Jenny Smith was a substitute professor for a local community college before the changes began. It all started on the day she turned twenty five, at the exact time. Her thigh burned and itched, and when she looked, it was a pastel colored hour glass that caused her so much trouble.

She, along with her friend named Dana, are slowly turning into ponies. But Jenny will soon find out, that not only is she becoming a pony, but also something more than that. Not only is she turning into a pony, but a certain alien that is the last of his kind in the whole universe.

This is my contribution to the Five Score, Multiplied by More group. I've always wanted to write about the adventures of people turning into ponies myself, so I decided to write a few fictions. This one is a bit less original, as it is in the Five Score universe, but it will eventually be a much more different story than most, as a certain famous alien that is the last of its kind is the main character in it.

Hope you enjoy reading!

My name is Steve Anello, son of Tony Anello. My old man runs the streets of Chicago with an iron fist. He's the big shot around these parts. However that's all about to change. Today is May 1, which means I'm turning 25. I don't know it yet, but my life as well as my body is going to be forever altered. It's going to be tough in the beginning but once I learn to control these "power's", I'm taking over Dad's operation. That is, if the rest of his boys will listen to a talking magical horse with a blood-red horn.

Rated T for language, some sexual references, and violence.

This is my contribution to Twisted Spectrum's awesome Five Score Universe.

Part Two Has Begun. Also, this story will tie in with another Five Score fic called, A Love For Madness. Read both to see events from different perspectives.

When John suddenly finds Luna's cutie mark on the side of both his thighs, a chain of reactions begins that is as far as he knows, irreversible. Are there any other people that are changing? Or is he completely alone in this world?
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Luna branch of the 'Five Score Divided by Four' universe. This story deserves a read as it is where this all started.
Credit for cover picture (Night Time) goes to Aeritus91
Collabing with: Total Eclipse of the Sun and Experiencing the Dusk

Curious about Five Score? Come check out the story that inspired dozens of side fics and been enjoyed by bronies for years!

Original Synopsis Even though MLP:FiM ended a few years ago, my friends and I still loved the show. Stories, merch, fan art, I loved it all. Things started to get a weird though when I found myself with a cutie mark appearing on my leg. Humans aren't supposed to get cutie marks, so where the heck did this come from? And what's going on with my hair?

More Detailed Synopsis: Five Score is an action/adventure story of the human-to-pony transformation genre. It’s unique from most transformation stories because the transformation itself is not really the point of the story. It’s the inciting incident that raises countless challenges that must be resolved. They are on earth, as a pony, and need to fix this before things get worse. Think about yourself in their hooves for a moment. How are you supposed to change back or even figure out what caused it in the first place? How are you supposed to get food or do anything on Earth without being spotted by humans? If you are spotted or captured, how would you escape? How does one even open a door with hooves!? Did anyone else on Earth get changed as well? How could you get the word out to the other ponies who are themselves hiding? Is it worth risking travel across the country to reach the others? Which of your friends would you trust to help you deal with this? And why did you turn into this particular pony? Surely it wasn’t random chance, right?

These challenges are the tip of the iceberg in this full length adventure novel There’s a lot of humor, many tense scenes, and hell maybe even a war.

But don’t just take it from me, Look what random people on the internet are saying about Five Score, Divided by Four

One of the best things to come out of this fandom.
-IrraticDrop

This made me change how I think about fictional worlds, imagination, and creativity
-relgukxilef

The only story on FimFiction to have me literally shaking with excitement.
-jeramiahsental

SWEET FILLY LUNA I AM FLIPPING MY SHIT RIGHT NOW
-Shadow Reaper

Five Score master editor:
Scrub

Five Score proofreaders:
Comrade Sparkle
Rustle my Jimmies

It is the year 2038, and the Earth is slowly being consumed by a space-borne monstrosity dubbed the Black Tide, which is using nanotechnology to remake the planet into something hideously alien.

Erin Olsen works for Project Harmonics, humanity's last-ditch effort to find a new world before the Tide can wipe them out. But when that world is found, and it turns out to be occupied, Erin will need to find the courage to face the unknown in order to save the inhabitants of both worlds.

(Many thanks to Easteu for the fantastic cover image for this story!)

Now with its own TV Tropes page

There is now a follow-up to this story: Sunflower - Side Projects
Sequel: Project Sunflower: Harmony