Um... Just stopped by here again and wow... A lotta discussion about that Berwyn fic I offhandedly mentioned. As someone who did skim through it a few years back, I can confidently say it was on Ao3. I just checked and it looks like it got deleto'd so let me give you my abridged retelling of the events as I remember them.
So the first chapter was about Berwyn running into a gang of baddies. I want to say they were cultists of some variety? Brutal >rape occurs. Berwyn then gets shoved in a guillotine and is bad ended. However, the story doesn't end. Through some shenanigans that I forgot because this was like five years ago, Berwyn comes back as a dullahan. And then I believe the rest of the story after was him going "The Crow" on the people who killed him.
Overall aside from the first chapter, the rest of the story was just your bog standard dark fanfic.