Princess Celestia tires of constantly being surrounded by decorum, deference, and formality, and decides to take a day off from being Princess. But visiting Ponyville incognito is harder than she expects. Will she be able to fit in and make friends without blowing her cover?

Daring Do cannot believe her luck when she is asked to help explore the most ancient tomb known to ponykind. But terrible danger awaits her, for beneath the earth rests something beyond equine understanding.

Warning: comments contain ending spoilers.

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Alternate ending by Duplex Fields.
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This story is a sequel to Past Sins

Side-story to Past Sins - Spike almost lost Twilight to a hangmare's noose, but now Twilight is safe and Nyx is a filly again. Normal life is returning. Still, Spike can't ignore the fact that Nyx just isn't the same as he remembers her. Her temper is more volatile, and, when she gets angry, all he can see is the rage-driven Nightmare Moon of legend.

And thus Spike has to wonder: Is Nyx truly reformed, or is she one bad tantrum away from calling herself Nightmare Moon again?

This story is a sequel to Past Sins

Side-story to Past Sins - Slowly, the wounds inflicted by Nightmare Moon's reign heal. Ponyville is being reconstructed, and the last refugees are leaving the castle. Nyx is with Twilight. Celestia and Luna rule Equestria and guide the sun and moon once more. Everything is as it should be.

But some things are never washed away. These are the things that remain to remind us of the past. They remind us of the good times we've had with friends and family. They never let us forget the mistakes we've made. Everyone has them. Twilight has them. Nyx has them.

And, on occasion, when you share your scars, your photos, and your trinkets with another, they just might share theirs in return.

This story is a sequel to Past Sins

Hearth's Warming is a time for friends and family to come together, celebrate harmony, and welcome the new year. Nyx is looking forward to just this as she rides the train to Canterlot with Spike and Twilight. She's going to meet her extended family for the first time and wants nothing more than to make a good impression. Yet, the sheen of the holidays can't hide the trouble caused by meddling grandparents, relentless reporters, and a paranoid uncle.

This story is a sequel to Scion of Chaos

Five years after the summer in which the three had gotten their cutie marks, Scootaloo, Sweetie Belle and Apple Bloom, now young mares in their own right, decide to go on a quick summer vacation, all as an attempt by Sweetie Belle to cheer up a sad friend. However, the trip turns out to be more than they had anticipated.

Set five years after Scion of Chaos and An Emerald Treasure. For the sake of context I'd recommend reading both of those first.

Special thanks to Mac349 and Plebeian for proofreading. Thanks to CMC4TW for editing/idea-mulling.

On a dark night filled with even darker magics, an insane cult attempts to give Nightmare Moon a body and life of her own, utterly separate from Princess Luna. But, when the spell is interrupted by Celestia, something unexpected is created.

Now, a little black alicorn filly named Nyx finds herself living under the care of Twilight Sparkle, only to be haunted by memories and emotions from her past. Is she Nightmare Moon reborn or is she simply a doppelganger with a soul and mind of her own? Can Twilight Sparkle protect Nyx from those who refuse to see past her dragon eyes and black coat?

Or, will Nyx be forced to inherit the sins that may not even be hers and become the greatest evil Equestria has ever known?

Twilight and her five friends are transported during a botched spell, across dimensions to... Ponyville, Equestria? But not the same one that they knew. Sitting on a bench is Harpsy and Babar. The Doctoress avoids apples from an aspiring Applebuck. And in a library across town, six stallions join their forces as they try to decipher the appearance of filly look-alikes of themselves around Ponyville!

"Cutie Mark Crusaders Alicorns, Yay!" Follow the CMC as they adjust to new expectations and find new crusading opportunities.
Is there enough aspirin in Equestria for the denizens of Ponyville who have to deal with three ever-helpful alicorn fillies?

What would you do, if you met a pony who was at once your brother, and yet not? Applebuck wishes to reunite with his 'Cousin JayJay', and braves the dimensional divide to reach his goal. But being a small foal, how will he deal with a world in which everything is flipped? His friends, his family, and even... himself?