I had the new-to-me privilege of being the first to post in a fandom on AO3. I am posting here in case anyone's read
The Private Memoirs and Confessions of a Justified Sinner by James Hogg (1824). It is about Scottish Calvinism, among other things. It was a great influence on Robert Louis Stevenson and his Jekyll and Hyde, among others. And one of the first instances of an evil doppelgänger in Western literature. I also found an audio book version narrated expertly (the Scottish accent is key to getting in the spirit of this one) by Peter Kenny and Nicholas McArdle. This was a fill for the Corsets and Lemons 19 century kink meme. OP wanted 'sexy selfcest murder persuasion.'
Justified (1500 words) by
okapiChapters: 1/1
Fandom:
The Private Memoirs and Confessions of a Justified Sinner - James HoggRating: Explicit
Warnings: No Archive Warnings Apply
Relationships: Robert Wringhim/Gil-Martin
Characters: Robert Wringhim, Gil-Martin
Additional Tags: Selfcest, Doppelganger, Doppelcest, Religious Fanaticism, Oral Sex, Intercrural Sex, Anal Sex, references to murder, Reference to child flogging
Summary:
Gil-Martin may be Robert Wringhim's evil side or he may be the Devil himself.
James Hogg's The Private Memoirs and Confessions of a Justified Sinner (1824).