Sunset Shimmer has hated Cadance since before they even met. After working her tail off for so many years as Princess Celestia's personal protégé, striving for perfection and aiming to eventually earn a royal title of her own, to have some random, two-bit nopony fall out of the sky and steal her crown felt like a kick to the horn.

So you can imagine Sunset's absolute delight when Princess Celestia assigns her to be Cadance's private magic tutor.

While at first it seems like some cruel punishment, Sunset quickly sees a golden opportunity. If she does this right, she might stand to gain far more than a mere grade.