We all know Twilight Sparkle - Element of Magic, unannounced leader of the Elements of Harmony, the savior of Ponyville and all of Equestria, and the most faithful student (personal student, that is) of Princess Celestia.

Before her, there was Sunset Shimmer, successful apprentice and excelling student in all but one aspect: the magic of friendship. She desired power, power beyond her wildest dreams - and Twilight showed her where true power lied: in her friends.

But surely, these two weren't the only apprentices of the Princess of the Sun!
And indeed, they're weren't.

Finding herself in a crossfire of arguments between her former students and the apprentice of her sister, Celestia decides to let go of a burden she'd been carrying in the past two centuries…

…by relating the tale of her very first personal student.