I Became the Villain Brother-in-Law After Transmigrating Into My Own Novel

When a struggling author dies and wakes up inside his own unfinished novel, he discovers he's been cast as a disposable villain destined to die in chapter one. Worse yet, he's married to the protagonist's sister! Armed with insider knowledge as the world's creator and shameless enough to ride the protagonist's coattails at every turn, he'll leverage his unique position to survive court intrigue, the apocalyptic Hundred Clan War, and divine bureaucrats watching from above. Who needs talent when you can just announce "I'm the protagonist's brother-in-law" and watch your enemies hesitate?