Post Sleepless In Ponyville-
Rainbow Dash has decided that she is going to spend some much needed quality time with her honorary little sister, Scootaloo. In doing so, she finds out more about Scoots than she planned, and that the filly really is in need of an older sister.
And she will be that big sister.
I'm posting this as an AU, mainly because it deviates from canon just after Sleepless In Ponyville. Plus, future installments will be later episodes that are set in this storyline.
Cover Art by lordyanyu