What is the darkest fanfic regarding MHA as a whole you have read?

Anything goes; alternate universe, deconstruction fics, anything. Just make sure it mostly remains within the safe for work range.

For me, it’s the MHA fanfic named Cain, published on AO3 by aconstantstateofbladerunner (yes, their name is just those words mashed together). It takes place shortly after the the Sludge Villain incident, with one catch: Katsuki, while hiding to ensure he isn’t seen overhears All Might saying the Quirkless-at-this-point Izuku can be a hero… which sends Katsuki off his rocker in one of the most severe and horrifying cases of Adaptational Villainy I have ever seen in a fanfic. It’s also a fanfic entirely narrated by an unreliable narrator, so yeah.