Your gateway to endless inspiration
at the crown of eternal sunlight
since its apparently scootadash hours in my brain:
rainbow factory dash knows that scoot wont pass her flight test because of her underdeveloped wings, and she cant bear the thought of her little sister being thrown into the grinder, so she knocks her out, kidnaps her, and amputates her wings
pegasi who lose their wings are seen as victims of circumstance rather than failures, so instead of being killed for their pigment to make rainbows, theyre allowed to live
when scoot is obviously devastated, betrayed, and furious, rainbow is just begging for her forgiveness through tears and trying to explain why she had to do it, this was the only way, she has to understand
in the end they make up a cover story about a lightning strike or a bad wildlife encounter in everfree and scootaloo lives out her life as an earth pony, but she is understandably pissed at rainbow and doesnt want anything to do with her for a long time, possibly forever
but rainbow is just happy that shes alive
with the knowledge that she wont have to watch scootaloos darling little face disappear into the blades of the machine, she can sleep a little easier at night
to rainbow, sacrificing scootaloos trust is worth saving her life