One of the main themes could be redemption. As the villain embraces the light, it often implies a journey towards redemption from their villainous ways. Another theme might be self - discovery. The villain is likely to learn more about themselves and their true nature through this process of embracing the good. Also, the contrast between good and evil is a key theme. It shows how the boundaries can be blurred when a villain starts to move towards the light.
The villain themselves would be the most interesting. Their journey from being a villain to embracing the light is full of potential for character development. They have to overcome their past, deal with their inner demons, and adapt to a new way of life. Also, any characters who oppose the villain's change could be interesting. They might be resistant to the idea of a villain becoming good and their reasons for that resistance can add depth to the story.
One of the main themes is destiny. It seems that the two main characters are fated to be together despite all the odds. Also, the theme of sacrifice is present. The girl sacrifices her normal life as a shaman and faces many hardships in the palace for the sake of her love for the king. And there's also the theme of loyalty, as the king remains loyal to the girl throughout the story.
Well, love might be a theme too. It could be a love that defies the expectations of the 'villain' label. Maybe the protagonist falls in love with someone in the villain's family and this love challenges the pre - conceived notions about the family. Also, power struggles within the family could be a theme. With the villain's family, there are likely to be fights for power, inheritance, or control.
Power struggle is likely a theme. As a villain, the character probably has to deal with other powerful entities, whether they are heroes or other villains, in a constant battle for power and influence. Also, identity might be a theme. The character has to grapple with being seen as a villain and how that affects their self - perception and relationships with others.
A common theme is the redefinition of what is considered 'evil'. In these light novels, the main characters' actions may seem evil at first glance, but as the story progresses, we understand their motives better. In 'That Time I Got Reincarnated as a Slime', Rimuru's actions towards other races might seem domineering, but he is also trying to create a stable world for his people. Another theme is the struggle against the status quo. The villain - main - characters often oppose the existing order, whether it is a political system or a social hierarchy in the fictional world, which adds an element of rebellion to the story.
One of the main themes could be the concept of being a villain. It might explore how the protagonist embraces this role differently from the typical heroic narrative. Another theme could be self - discovery. As the character lives as a villain, they may learn more about themselves and their capabilities.
One such light novel could be 'The Villain's Ascension'. Here, the MC starts off as a villain and undergoes complex character development throughout the story.
There's 'Dark Path Chronicles' where the MC is definitely the villain. The story explores their descent into evil and the chaos they cause.
I'm not entirely sure as I haven't read it fully. But generally, it might involve the relationship between the villainess and the villain. Maybe their schemes, their interactions with other characters in the story, and how they navigate the world of the novel which is often full of its own rules and social hierarchies.
In 'The Villainess Reverses the Hourglass', the main character is Aria. She was a villainess but gets a chance to change things. In 'I'm the Villainess, So I'm Taming the Final Boss', the female lead is the villainess who has to deal with the final boss. Often, the main characters in these novels are villainesses who are trying to rewrite their fates, either by changing their personalities or their actions in the story.