Changeling Heart: Saki's Granny
"it is princess celestisa's and princess luna's choice light...they both must come to an agreement, or you may stay here until they do decide."
My Little Pony: Equedia Ep.1 A New Arrival Pt.1
Even if we could do all this that fast, princess, er former princess luna can't go make everypony sleep to go checkin' their dreams," applejack reined in the runaway ego of her pegasus friend.
Lyra's Lesson
"well, i was playing my harp in ponyville, and princess luna was in town for some reason. well i was playing a song called 'thy calm night.'
My Little Delirium - Chapter 3
As twilight said, princess luna became jealous of her sister. all the ponies would frolic during the day, and sleep during the night, and luna wanted to change that. so she defied her sister, and created the long night, a night that would last forever.
Chapter Twenty-Three: Make Us Proud (edit 7/8/2015)
Been a long time since the last real storm when we gave a bloodied beak to our gryphon neighbors over 1200 years ago, when princess celestia and princess luna personally commanded the army to stand aside while they took the gryphons on by themselves and single-hoofedly
Burned Bridges [MLP]
I've been sort of helping princess luna and celestia with a study of theirs. and because i couldn't be doing it here, i had to be doing it in canterlot. so naturally, i spent lots of time there." "...okay so?" sugar blossom continued.
Chapter 1 – First encounters
"princess celestia and princess luna is the immortal rulers of equestria, they will need to know of a danger this great as soon as possible." t?shir? nodded, deep in thought. "you are right and i think we should talk with them too."
Born For Loyalty Chapter 8
"princess luna!" celestia said with force and the other mare jerked awake and looked at celestia with fear, "it's been a long time since i've seen you like this." celestia knelt down and luna winced in fear.
Antecedent 4
"princess luna denies that she has any knowledge of the guard at all, so it's a stalemate.
The Guardians of Equestria - Introduction
luna herself.
Chapter Three: Explained Extractions, Unknown Reasons (edit 2/13/2015)
Everything about it...yourself princess celestia, princess twilight sparkle becoming an alicorn and a princess, the elements of harmony, ponyville, canterlot, manehatten, princess luna during her fall from grace and after you sent your personal protege
The Guardians of Equestria - Chapter 2 – Mornings, Messages, Meetings, and Meanings…
Both princess celestia and princess luna were her mentors, princess cadence is her sister in law, prince shining armor is her big brother, and even spike had a small stake in being a form of royalty.