This story is a sequel to Hard Reset

After the events of Hard Reset Twilight's life and mental well being are slowly returning to normal. Her recovery is cut short, though, when a letter arrives informing her that the time loop spell she cast is causing severe damage to space and time itself. In over her head, Twilight tries to summon anypony who will know how to fix it. The pony she gets is the last one she ever thought she would meet... and nothing like she expected him to be.

Available in Spanish thanks to dgs1993
Series TV Tropes page

Twilight Sparkle is a curious mare, always studying, always learning. As she gets older it is only natural that she becomes interested in sex and sexuality. To help her study the subject of pet play she approaches the wisest mare she knows, and one she trusts as much as she trusts her own family.

Princess Celestia

A note: The story was tagged as it is, after consulting with story approvers. There is no actual sexual contact in this story. Re-tagged with the new Fetish tag.

Featured! O Frabjous day! Calloh, callay!
Thank you very much for bringing a smile to an old pone's heart.

Jonathan never slept much. This time, he reconsiders his habits. Jonathan was up at night like usual. Then, he hears a thud. When he investigates, he finds a small, purple unicorn, who doesn't know where she is. Soon, Jonathan will be forced to make a decision that will change his life forever.

Twilight Sparkle is a gifted student and scholar. When she attempts to harness her creative side by writing a science-themed sensual romance novel, however, things rapidly get out of hoof. Can her friends stage an intervention before she humiliates herself (and them) at a prestigious literature recital?

No. No, they cannot.

SF (canon species only; no humans) Ponies were magically and genetically engineered to be the perfect servitor race. They are powerful, adaptable, intelligent and completely under the control of their creators. A laboratory accident frees one such pony from her mental chains, but how can one mare save herself and the rest of her kind if she doesn't even know she's a slave?
This is not the Equestria you know and these are not your little ponies... not yet, anyway.

Tags: Adventure, Diamond Dogs, Gryphons, NO HUMANS (did I mention that already?)
Other tags: historical, mind control, Clarke's 3rd Law, excessive use of high energy physics, before they were famous.
Detailed review by PaulAsaran.
Cover art by endrome , used with permission.
Russian translation (partial -- 'unofficially' completed in the comments)
A Soot-Covered World, book 1.

Princess Twilight Sparkle is a teacher, a ruler, and the occasional savior of Equestria, and she loves it. Her jobs can be rewarding and fulfilling, but they can also be a bit exhausting. Hearing her friend is feeling a little worn out from all the responsibilities she has, Sunset Shimmer offers Twilight a holiday together across the portal in the human world. No evil magic, no intramural sports, and no one else. Just the two of them spending the entire day together.

Original art by Uotapo
Cover text generously added by Novel Idea

First story in the Rays of SunLight series.

Starlight Glimmer is about to embark on a few little friendship lessons. Five to be exact. However she’s still a little murky on how to get all her friends to cooperate so things go as quickly and efficiently as possible. Luckily A surprise visit from another friend might solve Starlight’s problem.

An alternative take on Every Little Thing She Does and inspired by a conversation with Tired Old Man.

Now in her late forties, Sunset Shimmer has built herself a career as a doctor. She has devoted her life to helping others, be it by prescribing pain killers or simply bandaging a scraped knee. A part of her longs to return to Equestria, but she is mostly happy with her new life. However, one day three very familiar girls drop by her office, one of them injured. Old memories flood back as Sunset is shown an unexpected harsh reality related to her high school life.

Worthless, weak, ugly—as far as Twilight is concerned, that's all she'll ever be. Even three months into their relationship, Twilight still refuses to believe that an absolute goddess like Sunset could ever love a loser like her. And it doesn't help that Twilight spends every night being tormented by nightmares of Midnight Sparkle, the one being who hates Twilight more than she hates herself.

Twilight can only remember a single moment in her life when she felt strong: the five minutes that she spent as Midnight Sparkle. The five minutes she spent with magic.

Now, tortured by fear, anxiety, and never-ending nightmares, Twilight knows the only way to win Sunset's love is to make herself stronger—even if that means resurrecting the demon inside of her.

Originally written for the January 2016 Writeoff, "Look, I Can Explain...", where it made finals.

Thanks to Horizon, Bookplayer, and FanOfMostEverything for offering advice on the original. Thanks to Quill Scratch, Oroboro, Monokeras, Lise Eclaire, Monarch Dodora, Majin Syeekoh, PegasusMesa, Reneigh Haycart, and Hazeyhooves for helping me brainstorm certain parts. Preread by Pascoite.

Art by Ta-Na!

One beautiful morning, Twilight Sparkle decides she wants a free salad. After a small amount of theft, assault, battery, and arson, she sits down to enjoy what is sure to be the best tasting salad ever.

...Or she would have, if it weren’t for the Equestrian Intelligence Service locking her up as a potential threat to national security. Now, Twilight must escape a maximum security holding facility hidden deep underneath Canterlot. And to do it, she’ll need a paperclip, a spymare catsuit, an escape plan, and an alliance with the dastardly Drakbog, King of Frogs.