Tell me how a series would change if MC were the villain. Who would be the new hero and how would the plot change?

And since today is Bookworm day I’ll start with the obvious:

Ascendance of a Bookwyrm: Urano Motosu, once a book-loving and kind-hearted girl, reincarnates as Myne, a fire-spewing dragon. After a century as a recluse in her dragon hort full of books she accidentally burns everything down in a fit of rage when she reads a romance novel and her favorite ship doesn’t sail. Desperately crying over the ashes of her lost hort she hatches a new plan. She transforms into the body of a little girl and tries to blend in with the human civilization of the Ehrenfest duchy. She begins to develop a book industry and finds promising authors but becomes quickly disillusioned with this new environment and its injustices. She realizes that her efforts to spread knowledge and literacy have been in vain, as the nobles and clergy continue to exploit and oppress the common people. Feeling betrayed and frustrated, Myne’s desire for change and justice morphs into a thirst for power and control as she turns back into her dragon form and forces everyone to write and print books for her ceaselessly after she overthrows the ruling class and becomes the new supreme ruler.

As Myne’s power grows, the Yurgenschmidt descends into chaos. Entire duchies are destroyed, innocent people are burned by a angry Bookwyrm for the slightest typos or when the wrong (in Myne’s opinion) ships sail. The nobles and clergy, who once oppressed the common people, are now forced to flee or go into hiding. The people are caught in the middle, suffering under Myne’s tyranny. Some of those people who once admired and respected Myne are shocked and terrified by her transformation. Her former friends and allies, including Benno and Lutz, are forced to confront the monster she has become under the guidance of the resistance leader Ferdinand. They must band together to stop her, but Myne’s cunning and magical prowess make her a formidable foe indeed.