Lyra thinks Discord is an idiot for not thinking to dodge when the Elements of Harmony were about to strike him. Discord thinks this is the perfect opportunity for a game.
How would a being like Discord want to be remembered after he's gone? Well, if you're curious, he did actually write a will. To the surprise of nobody, its contents are bizarre and mildly disturbing.
Flitter thinks Fluttershy is the weakest pony in the world. Flitter has never confronted what Fluttershy's job really means. Nopony ever wants to or should. Now Flitter has to. And 'weak' will turn out to be exactly the wrong word.
Celestia decides to attempt to reform Discord, so she taps a pony with a similar background for the job. ("Keep Calm and Flutter On" as it occurs in the Petriculture AU.)
When some ponies look at the Bearer of an Element, the Element is all they see. Fluttershy surely has no choice but to be kind, every time, no matter what. A belief which encourages that kindness to be abused.
Joyous Release has what she feels to be the worst talent and cutie mark in Equestria. She's approached Luna with a simple request: that the Princess rid her of both -- forever. A simple request which happens to be impossible...
There are things a Princess cannot do. Over the centuries, Celestia has been asked to do those things countless times. And the moments when her ponies need her the most are the ones where she can't do anything.