Rarity has a knack for seeing a pony's life story -- their pain, happiness and love -- with just a glance into their eyes. She has to be able to, after all, because not only does she have a younger sister she is responsible for, but she also owes it to a certain other pony. A certain other pony, who, because Rarity wasn't able to see into her, is now self-centered, reckless and lonely, never to live out her greatest dream.

A certain pony who now goes by Lightning Dust, instead of the loving nickname of "Dusty" Rarity had given her.