The Duke's RedemptionPlease Repent, Your Grace!; 공작님, 회개해주세요!; Duke, Please Repent!; The Duke's Redemption

I transmigrated into a novel and became an aide to the final boss of the story. The final boss dies in the novel, but only after the world falls to ruin. What if the final boss doesn't go down the wrong path? I have no choice but to try to redeem the soon-to-be final boss before it's too late!