Not ten years.
Not one hundred years.
Not one thousand years.
One million years.
An amount of time so ridiculously long, Celestia knew she would never see her beloved sister again. In fact, would Equestria even exist by that time? Would anything of the world she once knew remain? Why, oh why, did those Elements have such a terrible price?
Moping around in the library became Celestia's way to cope. Never really reading, simply grazing.
But one day, she stumbles upon a book that could change Luna's fate.
All it requires is sending Luna vivid stories, all comprised of cherished memories from their foalhood.
The catch? Luna must read them and write back, or the spell will not work. How would Celestia be able to convince whoever her sister had become to even open the letters?

King Sombra finally managed to break out of the ice. It wasn't much of an entrance, though, and the only witnesses were a couple of foals hurling snowballs at each other.
They have a few questions for him.

Celestia has invited Discord to the Grand Galloping Gala.
Discord has asked Rarity to make a suit for him.
What could go wrong?

Apple Bloom asks Granny Smith where foals come from.
Granny Smith tells her a rather strange story.

*PLEASE NOTE THAT THIS IS WAY CLOSER TO 'EVERYONE' THAN 'MATURE'*
Luna had always commanded Celestia to never, ever go in her room. Ever. Even on the moon, Luna managed to keep Celestia out.
But today, Celestia managed to find her way in.

Celestia made her own sandwich today, but something is wrong.
If there's anything being a princess has taught her, it's that sandwiches aren't supposed to talk.

Twaylite Sporkul is a magical unicorn and Princess Celestia's student. And when you're magical, stuff happens! Like going through a magical portal, becoming an alicorn princess, fighting bad guys, and a bunch of other stuff I'm not going to list!