Trapped in My Own Novel？Your Grace I Swear Im Not Lying

Web novelist Felix dies from overwork and awakens inside his own book as a disposable admirer fated to die in three episodes. A system orders him to keep military duke Leo alive or die permanently in both realities. Felix refuses to behave like the original sycophant, yet the world's correction force makes him drink poisoned wine meant for Leo, causing the suspicious duke to confine him. Using modern knowledge and knowledge of the plot.