Discord feels Equestria has become a little boring as of late. He feels the need to make life a bit chaotic. Pranks would normally alleviate this but the citizens of Equestria had become accustomed to Discord's antics. A lack of true friends sharing Discord's sense of humor in Equestria compounds his frustration. Another dimension provides the answer to both problems: a hypersonic octopus with a penchant for impossible feats, gossip, and sweets. Korosensei, the unkillable teacher, finds himself roped into Discord's scheme. Equestria is about to get a taste of Mischief from Tartarus infused with not-so-murderous intent and tentacles!
My Little Pony: Friendship is Magic and all affiliated characters belong to Hasbro.
Assassination Classroom belongs to Shueisha and is written by Yuusei Matsui.
Chronologically, this occurs after Make New Friends but Keep Discord/Rainbow Rocks (in MLP:FiM) and the Civil War Arc (in Assassination Classroom).
SPOILER WARNING: This story spoils events past Chapter 100 in Assassination Classroom.
Thanks to hiromiyamoto27 for pre-reading and help with story planning.

Twilight Sparkle has been unable to get any sleep for the past three weeks because of a dream. The saddest and most horrible dream she has ever dreamed. A dream where Rainbow Dash, the somepony she is in love with, dies. Spike has urged Twilight to tell Rainbow Dash, figuring it would stop the dream but the alicorn is just too stubborn to do so. What will Twilight do? Will she continue letting the dream keep from sleeping and risk driving herself insane or will she finally open up to Rainbow Dash?

There's only so much stress ponies can take before they need a break, and so Twilight and Rainbow take a vacation, but while they are there, Rainbow only further stresses Twilight out, much to her irritation.

I woke up in a room. A hospital room. There were seven visitors. A baby dragon, and six ponies. One of the ponies was obviously a doctor. Other than the doctor, there were two pegasi, two earth ponies, one unicorn, and a baby dragon. "Twilight?" the baby dragon whimpered. "Do you... Do you not... remember us?"

Now with a prequel, Celestia's First Sunrise!

Twilight is old and weak. She has lived a good, long life, and as the last of the Elements of Harmony, she accepts her death. She goes to Canterlot now, to say goodbye to the princesses. But they have one last gift to give the student. The chance to meet their creators and see something truly wonderful...

Spike and Twilight have been together for their whole lives, but what happens when the time comes when the friends are supposed to split apart? A long walk in the night reveals what the future holds for the duo.

Spilight.

Different decisions can change so many things about the future. How do you know what the right decision is? How do you know what you are doing is for the better? What if something so drastic happened that your whole life changed in an instant. You have less than five seconds to act, and you have no time to think about what you need to do. How are you supposed to make the right decision based on so little time? Even after it's happened, it's impossible to know what would have happened if you made a different one.

No matter what happens, you live with the consequences of your actions.

This story is a sequel to That Which Makes up a Rainbow

What are we? Are we just memories or is who we are something more? When everything is gone who are we in the end?

For one mare, that is a question with only one answer. She has a life with no past, but also with no scars. Follow her through the pain of building anew, when everyone around her clings to the past and to hope. What can be wrought from the turmoil of loss and birth? Could it be... a soul?

Math is simple. 1, 2, 3, 4, 5, and so on.

Ponies are not simple. They don't add up like regular numbers do, and just because one answer is four and the other is one does not mean the bigger number is necessarily greater.

Twilight experiences this inequality first hoof when one friend is pitted against four, and she is forced to choose a side, whether she wants to or not.

This story is officially cancelled. You can read my thoughts about it and why this happened here.

Scootaloo, now in the care of Twilight and Rainbow Dash, remembers her time as an orphan, and how she became their kid.