She noticed the pony for the first time when she was young, not long after she'd received her cutie mark. He became her oldest friend.

Note: comments contain spoilers; please don't read them first!

Cover art by DaisyAzuras • Featured in the Royal Canterlot Library

Reading by Neighrator Pony • Spanish translation by Spaniard Kiwi

The Unity Day party at Sweet Apple Acres goes awry after surprising accusations are leveled at Applejack, on account of some difficult-to-discern lyrics.

Find Iron Wolf's dramatic reading of this story, in a super cool Polish accent that kicks the whole thing up to 11, here.

Twinkie Pie. Appledash. Rareshy. You know these pairings and may have favorites of your own. But what if every member of the Mane Six were paired with every other member in the same fanfic?! That's what the Combinatorics Project is--an epic treasury of fifteen ships spread across five parallel universes increasingly full of plot and whimsy. Can you guess which couple is which?
* The angster and her secret admirer
* The burlesque showmares
* The celebrity marriage
* The commune farmers
* The curse victim and caretaker
* The dessert caterers
* The hopeless homebodies
* The industrial mavens
* The mad scientists
* The masquerade hosts
* The model train overlords
* The multiversal adventurers
* The orchard grafters
* The rivals in love
* The weather aficionados
Plus: Twilight blows up like a balloon and goes out to 'have a spicy time'! Applejack and Rainbow Dash are competitive about everything! Rarity dresses like a butterfly--and later in five outfits at once! Pinkiezilla crushes a miniature town and argues with Octavia about her instrument! Fluttershy dances with an angel and keeps a weather diary! Derpy tells a six-word joke! Not everypony ends up happy, but most do! A little suspense is a good thing. Bitter sorrow! Transcendent joy! Probability cupcakes are cupcakes that cupcakes!
Note: This story was written during Season Two, so a few small things are out of date.

Somepony struggles to remember their childhood. But something's wrong. The facts aren't lining up, and things are becoming blurred. What's at the bottom of this mystery?

Rainy weather and a looming deadline drive Twilight Sparkle up the walls and Spike out of the tree. Only Pinkie Pie can save the day, by introducing the reluctant librarian to an unexpected new hobby. Astoundingly, sex does not ensue.

To Twilight Sparkle and Princess Celestia, it is a simple surprise visit to Canterlot. To the ponies of the Equestrian Civil Service, it is twenty-four hours of chaos, politics, weaponized dessert, politics, underhooved manipulation of media, politics, and things batrachian and tentacular. Who said bureaucracy isn't exciting?

One by one, Twilight and her friends must come to terms with the consequences of being the Elements of Harmony.

These stories take place in the intervening time between Season One and Season Two,
with the exception of Ditzy Doo: Muffins, which takes place early in Season One.

The series continues in the sequel, Secrets and Lies.

Pony Psychology has a TV Tropes Page.

A letter from Celestia interrupts one of Pinkie's parties with disturbing news. Now friendships will be pushed to the limit as Twilight struggles to uncover which of her friends is not who, or even what, she appears to be.

(While not a romance, this does contain a shipped pair)

in Russian

Every night, in a little stable just outside of town, an old mare lays down to sleep. And every night she has the same dream of rainbows and open sky...

This story explores a dragon's nature somewhat, and spins a narrative of a middle-aged Spike regaling a visitor about the favorite item in his hoard: a statue of his favorite pony. It is a story about Spike, Rarity, reminiscing, letting go, and preserving that which is most precious to us.