When Twilight visits Celestia's private hall of stained-glass windows, each bearing the image of a long-gone friend, one in particular catches her eye.

Who was this pony?

Why was she so important to Celestia?

And why does she look so familiar?

There is now a Spanish translation of this story, courtesy of Spaniard Kiwi

For most ponies the day they get their cutie mark is the day everything changes. That was especially true for Twilight Sparkle, as the day she got her cutie mark was also the day Princess Celestia took her on as a student, she gained a new little brother and started on the road to her future.

It was also the day she became a dragon.

Custom cover artwork by Elza Fox
Editing and so much more by Klamnei