James Hogg 
The Private Memoirs And Confessions Of A Justified Sinner 

"The Private Memoirs and Confessions of a Justified Sinner" by James Hogg is a complex novel that tells the story of two brothers, George and Robert Colwan. George, raised by his father, embraces a carefree life, while Robert, influenced by his mother and a radical religious sect, becomes obsessed with Calvinist beliefs. The brothers' lives intertwine in Edinburgh, where Robert stalks George, leading to his untimely death. The second part of the novel presents Robert's memoirs, revealing his descent into madness and his encounter with a mysterious companion named Gil-Martin, possibly a manifestation of his own delusions. Robert believes it is his divine mission to eliminate sinners, leading to further crimes and a loss of identity. Ultimately, Robert takes his own life.