Sunset Shimmer's choices after the Fall Formal lead her through a darkness she thought she'd lost. Sequel/adoption attempt for Empty Lake, Full Sky by Wayward Sun.
After Tirek's defeat, magic was restored to everypony who it had been taken from - except Trixie. Now, injured and facing months of reduced magic, Trixie has to hang up the hat and cape, or risk destroying her healing horn forever. Hilarity Ensues.