There are ponies who insist on perceiving the Bearers as their Elements, and nothing more. Applejack is seen as having no qualities other than being honest. Rarity simply has to be generous even when doing so would hurt her. And Fluttershy must be kind. To those ponies, if she acted in any other way, no matter what the situation or provocation, it would mean she wasn't truly Kindness at all.
To see kindness as somepony's only possible response to everything is to take the first step in finding ways to abuse it.
To use kindness as the lone option can be worse.
Note: this is a direct sequel to Five Hundred Little Murders and this time, I will recommend reading that one first.
(Part of the Triptych Continuum, which has its own TVTropes page and FIMFiction group. New members and trope edits welcome.)
Now with author Patreon page.
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.
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.