The Redemption Arc of a Scumbag Writer TRASW

The very famous writer, Mathis Bauer, unexpectedly dies one night, shocking the world, but the real one who can't get over the shock is Mathis himself.
With the last thing he can recall being himself dying, Mathis Bauer wakes up in the body of one of his book characters, and a side villan character at that.

Not understanding what is happening and how such thing is possible, Mathis Bauer now is thrown in the middle of the war he himself as the writer plotted, knowing fully well that he's working for the wrong side.

Forced to live as the psychotic murder, Yue Zian, who dies halfway through the book in the hands of the main character, Mathis tries his best to change the ending of the book, all while helplessly goofing around and losing his shit over the main character and his love interest.