Limestone Pie goes to Griffonstone to...deliver rocks or whatever. While there, she wanders into the local bar. It goes about as well as you would expect, as she gets drunk and gets into a bar fight with the local griffins. Angry noseboops and squawking ensues.
This gives me the really weird idea...what if this is an imperfect form of a certain technique? Specifically, Ryouga Hibiki's Breaking Point technique? At one point in the past, Ryouga got so lost he ended up in Equestria, turned into a pony, and mentors Maud Pie. She's got the strength to keep up with him, at least. Probably a friendship/Ryouga teaches Maud martial arts story.
Limestone Pie would be standing off to the side, continuing to be a bitchy tsundere. She'd probably be the first pony Ryouga meets, actually. I have the perfect scene in my head already. He accidentally enters Equestria and after finding himself lost, sits on a giant boulder. Cue Limestone freaking out: "DON'T TOUCH HOULDERS BOULDER!"
Twilight Sparkle makes all her friends immortal. Unfortunately, Twilight neglected to check if she herself was immortal. After a freak accident kills Twilight, Twilight’s friends are left to pick up the pieces.
Could be done either way as a tragedy or a comedy, though I'm definitely leading to tragedy/drama sort of deal.