After Nightmare Night, Luna invites Twilight to tea, and they start spending more time together. Princess Celestia teases Luna about it sometimes.

In an Equestria without the Princesses or the guidance of the Elements of Harmony, Twilight Sparkle is a researcher on the cusp of her greatest discovery and simultaneous fall from grace while finding love at the same time.

Initially written for the May/June Twiluna contest. Proofreading and idea-seeding credit goes to Pearple Prose Rated Teen for language and implied sex/violence.

For Luna and Twilight, life had always been rather simple – eating treats, sleeping in the sunshine, and wandering the streets at night.

But all is not well on Equestria Avenue. A mysterious fox creeps through the shadows, Luna's past threatens to drive a wedge through her budding relationship with Twilight, and Twilight has to face the possibility of her normal life slipping away between her paws. Will their friendship be enough to save the neighbourhood from certain disaster?

Set in the Catverse (yes this is a thing now)

This story is a sequel to Apotheosis

Celestia leaves Equestria in the hooves of Luna and Twilight.

While she searches among the gods to answer her questions, Luna and Twilight must struggle to fulfill their own duties to ponies and to Equestria.
Now with a Spanish translation by SPANIARD KIWI: https://www.deviantart.com/spaniard-kiwi/art/Apoteosis-3-3-857110357

This story is a sequel to The Celestia Code

When the monsters created by the dark crystal engine escape their prison, it's up to Princess Twilight Sparkle to deal with them. She gets help and advice from Princess Luna, but things don't go as planned. In fact, when a pony who relies on logic and rationality tries to navigate the stormy seas of emotional entanglement while simultaneously saving Equestria from a horde of evil creatures intent on destroying everything they encounter, nothing goes as planned.
AUDIOBOOK by VisualPony
WARNING: Major spoilers in the comments.

Book 2 of the Alicorn Adventure series.

Goodreads Page
100% Approved by Twilight's Library!

The Badass Twilight tag applies more than ever, but please note the new tags.

This story is a fairly direct continuation of The Celestia Code. You might be able to follow it without having read The Celestia Code first, but it's better if you do.

The sequel is here: The Twilight Enigma

Most excellent pre-reading/editing done by the erudite AcademicPony and the dapper statoose!

For Luna, nothing ever seems to go right. Except when it does, it's wrong.

Written for the TwiLuna contest.

At the edge of the world, up high where the blue and the black merge, two ponies watch the stars and pass the time annoying each other. It's the third year anniversary of their first kiss and Luna has a gift for Twilight that only she could give. Twilight freakstakes it characteristically well.

If this makes it to the Feature Box I will eat my hat.

Celestia leaves to deal with a foreign crisis, giving her sister a chance to rule alone and become more attached to the modern world. She calls on Twilight Sparkle to advise Luna, hoping her student will be able to draw Luna out of her shell. With two major threats to Equestria already defeated in the past year, it seems like the perfect time to let Luna gain some confidence and experience in the modern world. After all, what are the chances of a third disaster occurring?

Now comes with complimentary tropes.

Twilight finds herself enthralled by Princess Luna and everything she represents. As Celestia's pride and joy, Twilight struggles to repress these feelings. But an old and well-known evil surfaces again at the worst time. Can Twilight fight off the spectres of the past?