* The Downward Spiral Saga by BolshevikMuppet99
* Into the Darkness by StevenStevenson9000
* Her Baby Boy, Her Toy by Ishtar the Unclean
* Too Young to Die by thebombhasbeenplanted

 

Circular Reasoning was dark when I read it as a teenager and made uncomfortable in my own mind. And even now re-reading it, it sends me into a depressive episode. Really excellent writing but just horrifically dark.

 

Lots of stuff has evaporated from memory over the years, but from has stuck around, CR is among the best in the category, even though it's unfinished and probably never will be.

A lot of "dark" fics just veer stupidly into pointless gore and rape. Writing a scene where a pair of teenagers have sex on a bed covered in the blood of the victim they had just disemboweled isn't "dark". It's just retarded. Writing a character capable of doing awful or morally questionable things that doesn't make the reader just roll their eyes--that's what darkness is. Sometimes standout moments of this appear in stories that aren't labeled "dark" as a whole. Honestly, it's not the easiest thing to write a story where your character begins in a dark place and desceneds further and be able to keep that engaging.

 

Not HP, but Path of Ruin fits here.

 

That one pokemon Black/White fic ages ago where Hilda ran into an insane!N at his castle and got psychologically and physically mangled trying to survive. Apparently his mother got eaten alive by a Zoroark pack when he was a child, and his sensitivity allowed him to hear their hunger. Survival instinct took over. So he joined in. Oof. Can't recall the title or find it again but its memorable.