It is common knowledge that Twilight Sparkle was not the first of Celestia's apprentices, even if only recent times were considered. However, what is not common knowledge is that mi Amore Cadenza was not the only apprentice to precede the current Crown Princess of Cant'r Laht. Years ago, Sunset Shimmer was apprentice to Celestia as a backup in case Cadence didn't work out and kept secret from all but a few, but she too proved lacking to the ancient sorceress and mysteriously disappeared. When she returns to find another occupying the position she thought she was destined for, her actions will lead her replacement into another world, a world Sunset Shimmer is well familiar with, but Twilight Sparkle is not. Twilight will have to travel to the World Across the Divide, a world very different from the one she knows. Not only will she have to learn of Canterlot Academy, a militarized school in a nation on the brink of a Great War, but she will also need to learn how to control a new body, one without sorcery at that.

In the same universe as Camaraderie is Sorcery, to be read between the third and fourth seasons (after Chapter 3:14.3). The canon-universe equivalent is the Equestria Girls movie.

This is the core story of the Camaraderie-verse.
Reading order:
Camaraderie is Sorcery, Season 1 (Ch. 0:0 - 1:27.4)
Lady of Love
Camaraderie is Sorcery, Season 2 (Ch. 2:0 - 2:27.3)
King in the North
Camaraderie is Sorcery, Season 3 (Ch. 3:0-3:14.3)
The Other Side of the Mirror: Vol. 1
Camaraderie is Sorcery, Season 4 (Ch. 4:0- )

Maps of Equestria
Season 1
Season 2
Season 3
Season 4

What if Equestria wasn't all sunshine and rainbows? What if the lands were wild, untamed, and ruled by powerful (and corrupt) nobles in the names of distant kings and queens? What if magic belonged not to every unicorn, but only to the privileged (and persecuted) few?

Camaraderie is Sorcery is a dark fantasy retelling of the story of Friendship is Magic. In this Equestria, the land is divided into kingdoms hungrily eyeing each others' lands and resources. This is a world where peasants are born, work, suffer, and die without their overseers shedding a tear. It is a world where bandits and monsters occupy both the wild places and the civilized ones (but in different forms). This is the world where Twilight Sparkle lives. Cant'r Laht, a shining city perched on the edge of a mountain with more nobles and mages than it knows what to do with, has been Twilight's home her whole life. Now, as the one thousandth summer solstice of the Fourth Age approaches, she will leave Cant'r Laht and depart for the tiny hamlet of Ponieville, where five companions await her. These Brave Companions, as the ballads will come to commemorate them, are already bound by destiny, though they do not know it yet. For who would ever imagine that a sorceress, a farmer, a Hunter, a blacksmith, a druidess, and a baker would ever become comrades with the strength to stop the end of the world?

Author's Note: I drew inspiration from several dark or realistic fantasy sources for the world of Camaraderie is Sorcery, but the most influential was the world of Andrzej Sapkowski's Witcher novels and CD Projekt RED's video game series of the same name.

When Celestia realized the calamity and chaos that would come to Equestria and that she would need somepony to take her place, she began to look for an apprentice. Eventually, this led to her tutelage of Twilight Sparkle, but she was not Celestia's first apprentice. This is the story of Roberta mi Amore, and how she became The Lady mi Amore Cadenza, heir to Celestia, and the first sorceress to become an alicorn in over a thousand years.

In the same universe as Camaraderie is Sorcery, to be read between the first and second seasons (after Chapter 1:27.4).