History's Royal Pain

A historical fan fiction novel with a touch of fantasy. | A university boy woke up in another world as the God of war, the supporting character of the villain in a historical novel. He knew the doomed ending of the story and tries to switch to the good side, breaking the original plot of the novel. He befriends the crown princess, Anastasia Adelaide in the story in reverting her fate and for him to get out of the novel as well. But will he get out of the novel? will the God of war and crown princess successfully change their fate?