Villain x Villain

Keith Rovan, a crazy guy who got transmigrated inside a novel as an extra named Eric Jonas. In the novel, Eric was a child who never received any kind of love or affection from his family because of that, the struggle he had to face are numerous. However, the silent endurance of his hardship, slowly leads him to the edge of suicide as an escape from the cruel world.
Who wants to live and die like that character, especially Keith who had an polar opposite character of weak Eric. So eventually, he decides to change the original plot. Not by acting as an angel, instead a devil who lives for his own desires without concerning anything. He never hesitates to dominate over others or eliminate the ones that dare to cross his path. However, his path dramatically leads him towards the future ultimate villain, Abaddon Mir.
They are born enemies because of their families, rivals in name, but what crazier is… with time, the rivals are turning into toxic lovers.