While relaxing after a performance, the Rainbooms discover Sunset has scars that she definitely didn't have before the Fall Formal.

As of 9/14/2015, this story has a dramatic reading by Goombasa. Give it a listen!

7/7/2016: Now with cover art designed by the very generous Novel-Idea! Thank you so much!

7/23/2016: This story has a reading by Gabriel C Media. Give it a listen!

Sunset Shimmer is having the worst day of her life. She used to be important. She was the personal student of Princess Celestia. She was a future leader of Equestria. She was the kind of mare that everypony envied.

Today, it's all crashing down around her.

Alternate Universe: What if Sunset Shimmer hadn't gone through the mirror?

When Twilight Sparkle was just a kid, her best friend was a girl named Sunset Shimmer. Though their friendship had a bit of a rocky start, they quickly became inseparable, no matter how much everyone thought of them as ‘weird’. They were there for each other.

Were.

Years after the tragic accident that tore them apart, Twilight is determined to move on from her loss, and she sets off on an independent research project to investigate the strange happenings at Canterlot High. Little does she know that she will soon come face to face with what appears to be a literal ghost from her past.

Coverart by Kare-Valgon. Chapter illustrations by Zorbitas.

Edited and Pre-read by Dubs Rewatcher, r5h, and Kalan.

Takes place after Rainbow Rocks, but was written before Friendship Games and does not take it into account.

Chinese translation

Print copies now available.

This story is a sequel to How Not To Use Your Royal Prerogative

  In an Equestria where the Sonic Rainboom never happened, Sunset Shimmer is the prized pupil of the Princess of the Sun. As Sunset struggles to make up for her past misdeeds and come to terms with the pony she wants to be, Celestia sends her to find the classic work The Application of Unified Harmony Magic from the Royal Canterlot Archives.
  Right after lunch, some meddling by her friends and meeting somepony with firsthoof experience of the Sunset she used to be.

Featured on Equestria Daily on August 18, 2016!
Appeared in the FimFiction Featured Box!

Cast: Sunset Shimmer, Moon Dancer, Minuette, Twilight Sparkle & Princess Celestia

Stories set in the Wavelengths Timeline in chronological order:

Origins Arc
The Alchemy of Chemistry
Bards of the Badlands
Grading on a Bell Curve
Habits of the Equestrian Phoenix
How Not To Use Your Royal Prerogative

Applications Arc
The Application of Unified Harmony Magics
Princess Celestia: A Brief History
The Cloudsdale Report

Dreamers Arc
Tactics of Snowbound Unicorns
A Study in Chaos Theory
Teahouses of Saddle Arabia
As the Raven Flies

Cover Credits
Cover Design by Amber Spark
Sunset Shimmer Vector by TigerBeetle
Pony SciTwi Vector by Osipush
Canterlot Bookshelves Vector by FavoriteArtMan
Sunset Shimmer Cutie Mark by MillennialDan

Beta Reader Credits
Ebon Quill - Worldbuilding Writer on The Manehattan Project
Quantum State - Technical Director of The Manehattan Project
The Albinocorn - Master of Sunset Shimmer Stories

Strongly Recommended Stories:
The Brightest and the Best by Pineta - The events in this story are considered to be completely canon to this timeline and explain Twilight's entrance exam to Celestia's School for Gifted Unicorns. I cannot recommend this story enough.
MLP Annual 2013 - "The Fall of Sunset Shimmer" - As above, the 8-page short comic in the beginning of the Annual is also considered to be canon, though with some major variations.

Version 3.0 Edit: Extensive grammatical and mechanics changes. Adjustment to timeline of Sunset's second mirror experience.

This story is a sequel to The Freeport Venture

As Freeport's best problem solver, Puzzle Piece finds himself helping the Magus-for-hire Sunset Shimmer with a job once again. The Sweetash family, one of the richest families in Freeport, has contacted Sunset with a new job to investigate ugly new rumors surrounding one of their rivals.

While the job seems straightforward enough, they quickly find out how a sweet deal can become sour.

Life is looking up for Sunset Shimmer.

With her grandstanding at the Battle of the Bands, Canterlot High has taken a new approach to her. Amends have been made, friendships have been restored, and Sunset is on the fast track to becoming a better person.

But even now, there are still apologies that have to be said.

For her Spring Break, Sunset returns to Equestria to make up with her estranged family: the parents that raised and provided for her, and the sister she left behind. But a lot has changed since then, and some wounds won't heal by just saying 'I'm sorry.'

Fixing friendships is one thing. Sunset will be put through her hardest test yet when she tries to bring her family back together.

Another one edited by Cerulean Voice.

Stunningly amazing cover art drawn by Ayemel!

Featured on Equestria Daily.

Listen to the audio book here!

No one has seen Sunset Shimmer in a week after the Fall Formal. Principal Celestia is getting worried. She doesn't really know much about Sunset Shimmer, but she is aware that she is alone in this world. When Celestia finds Sunset it is worse than she knew. Now, Celestia moves to heal the heart of the girl from another world. It is to be a difficult and hard fought battle against Sunset's own perception of self.

Can Sunset turn her life around from the downward spiral that it is in? Or is she right to believe that she is only a demon and deserves only the worst in life? Sunset's journey to forgiving herself starts with allowing her mentor's alternate into her life, but does she deserve to have the chance to disappoint two Celestias?

Now being edited by devas and The Albinocorn

Featured! August 18th 2014! For all of 10 minutes! Still counts!
Freatured again! September 15 2014! For a much longer time! Last time I update this bit though.

As the eternal regent of Equestria, Princess Celestia's knowledge of magic is without equal. Over her long life, only a few gifted ponies who had a great destiny before them have had the honor of learning at her side. Sunset Shimmer was one such pony: one of Celestia’s best and most promising students. As she learned at Celestia’s hooves, their bond strengthened until they became far more than student and teacher to one another.

Sometimes those closest to us are the ones who can hurt us the most.

[Note: This story does not directly tie into Equestria Girls]

The wheel of time turns, as destiny and history clash together.

Fifty years into the future, Sunset Shimmer is Princess Twilight Sparkle's most faithful student. She is smart and eager, but doesn't always think things through. Her life had been perfect, right up to the End of the World.

With a ruined future, Sunset travels into the past to alter the course of history. With only her mentor's cryptic word to go on, Sunset and the Elements of Harmony must solve the riddle of the Dark Regalia and stop the mysterious Vesper Radiance from rising to power. But the further Sunset goes, the more she feels like she's been through it all before.

Is destiny set in stone, or can Sunset shape her own future? Only time will tell.

Featured on Equestria Daily 6/16/13
Gratefully edited by JustAnotherTimeLord, Icarus_Gizmo, Cerulean Voice and Bad_Seed_72

The Sunset of Tropes page!

Darkness. It was a strange and ominous thing. It creeped through every crack and absorbed the light. The murkiness was clouded and it filled Sunset Shimmer’s eyes as they slowly peered open. She looked around, dazed and confused on what was happening, and where she was. The smell of forest filled her lungs as she stood up slowly on her feet hooves. She paused, her hooves. She screamed, ’What?!’ She examined the rest of herself. “Oh no no no no, this can’t possibly be right!”