Shadow of Loyalty Chapter 1
Squirt looked like rainbow just said she was nightmare moon. "what? why?" "because i can't stand being here anymore. i discovered the truth about mare do well, and it's not pretty.
Chapter Three: Explained Extractions, Unknown Reasons (edit 2/13/2015)
The farthest back i can go is when you were sent to ponyville not long before the return of nightmare moon.
07 - Between Heaven and Equestria
"nightmare moon is a category ten threat to equestria," blue shield reported with military precision, "but reports are still inconclusive when it comes to princess luna."
Prelude to Madness
No, this is surely all nightmare moon's doing! she must have been in league with that twisted schemer of a draconequus! no... no, rarity.
Little Star Chapter 2
The tale of nightmare moon started one thousand and eight years ago..." \* \* \* \* \* \* luna looked on with relief at the sight of her citadel. the citadel of the stars was her haven for her precious bat-ponies.
05 - Luna’s Call
The glow of her power surged and a stab of raw fear played through blue shield's senses as he recognized some of what made nightmare moon earn the title.
Through A Glass Darkly - 7 (final)
"i would think that the nightmare moon incident..." "if anything that was the inverse, a lack of power, not an excess," celestia smiled back. that was ancient history by now.
The Guardians of Equestria – Chapter 1 – Awkward Moments, Questions, and Conversations
It was exactly the same as it was when we faced nightmare moon... ... i kept looking through the castle until i found s-something that was different...
Not I: Murderous Mares / Betrayed
A flash of lightning lit the throne room through the stained glass windows; she could have sworn she saw nightmare moon in luna's place. twilight stood there, stunned at the realization. it was all a lie?
An Empty Reality
He was staring up at a depiction of the mane six battling nightmare moon while angelic shafts of light bathed them in a multicolored glow. when kevin pulled his gaze away from the image he found the rest of the hall full of other such scenes.
Little Star Chapter 5
Her fur was a darker lavender, and her eyes were like nightmare moon's but, again, in a darker lavender color. her expression was of cold calculation. her reflection opened its mouth to reveal sharp teeth.
Alter Destiny Chapter 3
"and i would still be the original nightmare moon and either banished again or destroying the world in eternal night.