This story is a sequel to I'm sorry, Sis: Scootaloo
Rarity is not having a very good day. First, her sister Sweetie Belle gets involved in a fire at Sweet Apple Acres with the other Cutie Mark Crusaders, spoiling Rarity's plans to spend time with Applejack and Rainbow Dash. Deciding to return Sweetie to their parents, Rarity makes a new plan for the evening.
What Rarity doesn't seem to realize is that she may be letting her anger get the best of her. As she continues to rage and blame Sweetie Belle for everything that goes wrong, the simple truth behind the whole sequence of events continues to elude her, and she is set on course to making a terrible mistake.
(Side story to I'm Sorry, Sis: Scootaloo, which isn't required reading. Edited by TheShadow)