WRITTEN BEFORE SEASON 5!!!
Without altering anything canon up to season 4 (though the movies are kind of skipped over, sorry), I manage to completely rewrite everything that happened. No, seriously. And it all started based off of Discord's photo-bomb in Fluttershy's window during the season 4 theme.
What if, rather than leaving with Celestia after he was reformed, Discord ended up staying at Fluttershy's house, unknown to any of the other ponies? Chaos ensues. (Pun intended. )
Definitely a Fluttercord.