Rebirth of the Villain was an online romance novel that told the story of a woman who was treated unfairly by fate and used her wisdom and ability to change her life path after being accidentally reborn to become the Villain. In this story, the heroine was originally an ordinary girl who was treated unfairly by fate and suffered many setbacks and blows. In the end, she used her wisdom and strength to successfully counterattack and reach the peak of her life. The plot of the Reborn Villain was complicated, and the characters were well-liked by readers.
First, try to understand the plot and the role you are supposed to play. Then, you could try to change your 'villain' image. For example, instead of causing trouble for the main characters, you can offer your help in a subtle way. This might change the original storyline and your fate in this new world.
Brainiac could be the villain in a Superman's son kidnapped fanfiction. Brainiac is known for his thirst for knowledge and power. He might kidnap the son to study his Kryptonian physiology and powers. Zod, another Kryptonian, could also be a culprit. He may have different ideas about how to raise a Kryptonian on Earth and decides to take Superman's son to implement his own vision. Additionally, a new, original villain created specifically for the fanfiction could be the kidnapper, perhaps a mad scientist who wants to create a hybrid using Superman's son's DNA.
A new character could be introduced as the main villain. This could be a powerful wizard or sorcerer who has a vendetta against the protagonist's family or race. They might be jealous of the powers that the 'Son of the Stars' possesses and want to take them for themselves. They could start by causing chaos in the protagonist's home town, slowly building up their power and influence.
It could center around the son of a villain who discovers a miraculous of his own. This miraculous might be different from the ones Ladybug and Chat Noir have. He then has to learn how to use it while also dealing with the fact that his family is against the heroes. His journey could be about finding his own identity, whether he wants to follow in his family's footsteps or become a hero in his own right. He may also face challenges from other villains who don't trust him because of his family ties.
You could expose him to positive influences. For example, introduce him to kind - hearted characters in the novel's world. Encourage him to participate in good deeds. If he is reborn as a villain, it doesn't mean he has to stay that way forever. By surrounding him with positive energy, he may start to change for the better.
It could be a rogue ninja who has a vendetta against Naruto and decides to target his son. Maybe this villain was once defeated by Naruto and now wants to take revenge by harming his family.
A rogue ninja who has made a pact with dark forces. He wants to use Goku's son to open a portal to the Saiyan planet and then invade it. He would be constantly trying to manipulate the situation to get Goku's son to do his bidding. He has a team of minions who are also skilled in both ninjutsu and some dark form of ki - like powers.
Ladybug and Chat Noir would likely be main characters as well. Since it's a Miraculous Ladybug fanfiction, they are important figures in that universe. They would interact with the son of the villain, either as enemies at first or as potential allies. And then there could be the villain parent. This character would have a big influence on the son's life and actions, constantly pulling him towards the path of villainy.