Princess Twilight Sparkle discovers a centuries-old mystery hidden in the Royal Archives. Her investigation leads through layer after layer of deception and misdirection, setting her hooves on a path that seems to be leading to a mysterious secret. Along the way, she learns that some friendships can be very, very strange.

Book 1 of the Alicorn Adventure series.

AUDIOBOOK by VisualPony
Featured at the Royal Canterlot Library
TV Tropes Page (Courtesy of Sandtalon)
Goodreads Page (Courtesy of Facedeer)
Equestria Daily Page

WARNING: Major spoilers in the comments. Takes place several months after the end of season four. (Not a Da Vinci Code crossover, BTW!)

Do you see a dark tag? No, you don't. Not dark. Well, okay, there are a couple of dark-ish bits, but that's all. Not enough to warrant a tag. Speaking of tags, there really ought to be "Badass Twilight" and "Friendshipping" ones.

Sequels and side-stories (and more) can be found here Offprint and AO3, and a hardbound two-volume set of all that can be ordered from The Ministry of Image.

My editor for the first edition of this story was Gogito, and I can't thank him enough for all the hard work he did. My editor for the revised version was PresentPerfect, and he did a terrific job of getting the story into excellent shape.

A brave stallion goes on a quest to save the world by finding a lost princess in an enchanted forest. Things don't work out as he planned.

WARNING: Some spoilers in the comments. Also, a few mild spoilers for the Alicorn Adventure series, though it's not necessary to read those stories to understand this one.

Equestria Daily Page
Goodreads Page
Zabaware/AT&T Natural Voices "reading" by Modoc

This story is a sequel to The Luna Cypher

Twilight sets out to learn more of the ways of the world, and soon decides that the whole planet is disorganized, insanely dangerous, and desperately needs to be fixed. And she's just the mare to do it... with a little help from her friends.

Also, there are sky-pirates!

Book 3 of the Alicorn Adventure series.

A few extra, slice-o-life chapters are here: On the Rocks

Princess Twilight Sparkle is perfectly happy with her perfectly ordinary life in Ponyville. Every library book is properly shelved in its appropriate place, and her life continues on exactly according to her meticulously planned out schedule.

Then she gets a bodyguard.

Now she has to find some way to fit this new pony into her life on short notice. It won’t be an easy thing to adjust to—especially since Captain Storm Kicker’s presence makes it that much harder for her to go on living like the same old Twilight Sparkle she was before she became a princess.

This story is a sequel to The Life and Times of a Winning Pony

Cloud Kicker's life has been going just about perfectly. She's got a good job, two beautiful girlfriends, and she's never been on better terms with her friends. She's even getting more time with her family now that her cousin is serving as Princess Twilight Sparkle's personal bodyguard. She made mistakes in her past, but now all of that is over and she's earned her happily ever after.

Or at least, that was what she thought. Little does she know that her new life is about to start getting very complicated.

This story is a side story to Crystal's Wishes

On the surface, Velvet Step seems like a pretty straightforward mare. She is in the Canterlot Ballet, the dutiful daughter of Sunbeam and Pepper Ridge, and the very best of friends with Crystal Wishes, her fillyhood friend and current roommate.

However, Velvet has another side to her, one that not even Crystal knows about, and she is keen on keeping it that way.

This story is a sequel to Past Sins

In the wake of the battle with Tirek, Twilight Sparkle becomes fixated on restoring Golden Oaks Library. After all, it was home for her little family of three. But as her attempts to repair the books and tree continuously fail, her friends must take matters into their own hooves. Discord, as the good friend he is, tosses Twilight and her extended family into an unexpected adventure while Twilight's other friends get to work on the new crystal palace.

All together, they'll do everything to ensure Twilight and her family have a place to call home when they reach the end of the road.

"...The test ends when you open that door."

Princess Luna has begun searching for her own personal student, and her test has hit a small snag: Not a single unicorn, out of the dozens of applicants, has passed. In fact, every last candidate has failed the test in seconds.

But just what is the purpose of this test? And how can somepony pass it?

A young earth pony named Morning Glory is going to find out.

Days after Tirek's near-takeover of Equestria, The Great And Powerful Trixie travels to Ponyville, intent on settling her rivalry with Twilight Sparkle once and for all. No trinkets to fudge her abilities, no megalomania to apologize for -- just pure and simple magician's honor!

Upon her arrival, however, she quickly learns that the information she has on Ponyville -- and Twilight -- is more than a little dated.

Edits (as well as a bit of scene inspiration) courtesy of nanashi_jones.

This story is a sequel to Avocation

Life in Ponyville has been relatively quiet recently, which is somewhat surprising, given that the town's librarian tried to usurp the Equestrian throne only a few months ago. Aside from the appearance of a grumpy pegasus who set up shop as a cloudsmith, the aftermath is so unnoticeable that most ponies aren't even aware that the incident happened at all. Unfortunately, all that's about to change, thanks to the return of a certain revenge-obsessed showmare....

This is the fourth story in The Petriculture Cycle; reading the first three stories, which begin here, is highly recommended.

The artwork was provided by Page Turner, and the TV Tropes entry can be found here.