I Entered the Tragic Novel I Wrote

[A reader who finished the story said in the comments that the blurb differs somewhat from the actual story. The story itself takes precedence.] Shen Muxin is a guy who writes angsty fiction. His hobby is writing stories that torment the male lead. One night, he accidentally transmigrated into a book as a cannon-fodder character with the same name, destined to be tortured to death by the male lead. Seeing the male lead on the verge of going completely dark after being tormented too much, Shen Muxin panicked. He turned over a new leaf and started diligently raising the protagonist's favorability toward him. Eight years later, after successfully retiring from the story, Shen Muxin was seized by the book's villain and faced with being sacrificed to the city. The male lead, whose favorability he'd maxed out, arrived at the city gates with an army of a hundred thousand. "Hand over Shen Muxin, or I'll flatten your city." After being rescued, Shen Muxin thought he'd latched onto the male lead's power and could finally live in peace until he died. He never expected to be thrown straight into the bridal chamber before his pressure points had even been unsealed. The protagonist lifted his red veil and leaned close to his ear, asking softly, "When you created this world, did you enjoy tormenting me?" Shen Muxin: "!!!!" One-sentence summary: Tormenting the protagonist feels great for a while, but transmigrating into the book means a fiery reckoning. Theme: