This looks like a good occasion to ask: how reliable is fimfiction.net rating system?
I have cautiously read a couple of top-rated stories on fimfiction.net and found them really good. But I know there are nastier ones out there, and those I would like to avoid.
Am I safe just by not clicking the prominent "View Mature" checkbox? But should't the story automatically fit into "Mature" if it's labeled Dark or Tragedy?
At FimFiction, when an author labels a story 'mature', they have the option of selecting from one of two sub-categories: sex and gore. A story can be Dark or Tragic without those elements, and it's at least plausible that even a story with gore might not be Tragic, and might even be a comedy, ala Shaun of the Dead. So, avoiding the Mature checkbox will certainly help you avoid such stories - but there are some edge cases which might slip through.
Another list of high-rated stories is Equestria Daily's Star 6 ones. I don't recall any that made it to that ranking that include content that's erotic, though some are somewhat dark, such as "Background Pony"'s horror aspects.
Equestria Daily is a reliable source of pretty-good pony stories. But they don't like risk. For an idea of what kind of stories you're likely to find there, go look at the pony art on deviantart, and then look at the tiny subclass of it, stylistically, that ever appears on Equestria Daily. They posted Fallout: Equestria, and some other risky stories. But they have their own idea of what ponydom should be, and the pre-readers speak in their correspondence as if they had the authority to speak for EqD and for other pre-readers, so I presume they talk with...
For the past two months, I've been writing, and posting, roughly two thousand words a day of "Myou've Gotta be Kidding Me", a story set in a "My Little Pony: Friendship is Magic" fanfic universe, "Chess Game of the Gods". Outside of the sheer NaNoWriMo-like exercise of pushing out near-daily chapters, I've also been trying to keep in mind the various principles I've learned from Yudkowsky and LessWrong, and to try to present them in a way that people who like reading MLP fanfics might be able to appreciate.
I've just come to something of a minor climax with chapter 60, and while I'll definitely be continuing the story, this seems like a good time to mention it here, for whatever feedback and constructive criticism anyone cares to offer.