Everypony remembers the ‘Best Young Flyer’ competition, especially the white unicorn with the butterfly wings, but few ponies know that there was a fleeting moment when Rarity actually had the most beautiful thoroughbred white alicorn wings.
Being an alicorn princess is Rarity's dream and Twilight's nightmare, so the two of them decide to swap roles for a week to see what their lives would be like if they had what they wanted.
Luna's has enough to deal with as Princess Twilight's student. Between nightly nightmares of moon princesses and the threat of an old enemy returning from Equestria's past, Luna isn't going to be getting any sleep any time soon