User blog comment:AMysteriousFanficReader/What is the worst fanfic you ever read?/@comment-32202721-20170925222317

If we're just talking about TLH fanfiction, then I'd say "Lincoln is Done", discounting the ones that are too lewd and grotesque to mention here.

In general, I'd say "My Big Flare: Friendship is Epic", an absolutely insufferable MLP fanfic from about five years ago.