Well, spoilers for a sequel could involve the villainess facing unexpected rivals or having to deal with the consequences of her past actions in more complex ways. But it's best to discover these as you read.
The biggest spoiler of 'A Beast Tamed by Villainess' is the revelation of the protagonist's true identity. It completely alters the way you view the story. Also, there's a surprising turn of events in the final chapters that you wouldn't expect. However, it's best to discover these while reading the book.
Another challenge is maintaining her power. In a novel's world, power is often a tenuous thing. She might have to deal with political intrigue, like court factions vying for influence. She has to outwit her opponents and make shrewd decisions to keep her position as empress. Also, she may face the problem of public opinion. Even if she is villainous, she still needs some level of support from the people, or at least their fear and obedience. If she becomes too tyrannical, it could lead to uprisings.
One main theme could be self - discovery. As the character becomes a 'true villainess', she likely discovers new aspects of herself, both good and bad. Another theme might be power dynamics. In the role of a villainess, she has to navigate through different power structures in the story's world.
One main theme could be self - discovery. As the character becomes a 'true villainess', she might be exploring a new side of herself. Another could be power dynamics, like how she wields her new - found villainous status in the social hierarchy. And also, there could be a theme of redemption or change as she may not stay a villainess forever.
Well, of course, the main character is the one who becomes the 'true villainess'. There might also be a male lead, perhaps a hero or a love interest who is in conflict with her new villainous nature. And then there could be secondary characters like her family members, friends from before her transformation, or other villains in the story who she may interact with, compete with, or form alliances with.
Power and corruption could be a central theme. When becoming a 'true villainess', she may be tempted by power and gradually become corrupted by it. Love and hate is also possible. She might have complex feelings towards the people around her, such as hating those who oppose her and having an unexpected form of love or attraction to certain characters. Additionally, redemption could be a theme. Even though she's becoming a villainess, there could be a chance for her to redeem herself in some way.
Survival could be a key theme as well. In a world where being a villainess might make her many enemies, she has to find ways to survive, whether it's through political intrigue or outsmarting those who would bring her down.
Perhaps there is a love interest who has to deal with the protagonist's transformation into a villainess. His reactions and how he tries to handle the situation could make him an interesting character. Also, there could be a rival character who is constantly at odds with the villainess - to - be, and their battles of wits would be engaging.
The protagonist herself is very interesting. Since she has become a 'true villainess', her character development is something to watch. There might be a love interest who has an unexpected reaction to her new persona. And perhaps a rival character who challenges her in different ways.