This is a kind of "X files" thread.
Post experiences which spooked you, which made you doubt reality, mathematical or physical laws, your sanity, memory or perception. The more improbable the better, but no second-hand legends please, share only what you personally experienced. If you had the event later explained rationally please use rot13 to avoid spoilers.
Read them both, enjoyed them both, and didn't find either even slightly horrifying, although I think I understand why I am supposed to find them horrifying (Fun-theory-wise). I'm genuinely unsure if I should be trying to fix myself on this count.
Those who have a) read them, b) been horrified by them (either for EY's reasons or different ones) and c) would be reading more pone fanfic anyway, I'd be very curious to know if the existence depicted in MLP Loops is more, less, or differently horrifying to you.