Maybe the sludge villain has a sidekick or an accomplice who is enraged by his death. This person decides to take revenge on the heroes, especially the ones directly involved in the sludge villain's demise. They start targeting the hero's friends and family, creating a more personal and dangerous threat for the heroes.
For Izuku Midoriya, if he was involved in the sludge villain's death, it could be a major turning point in his confidence. He might struggle with the fact that he took a life, even if it was a villain's. This could lead to him questioning his role as a hero and his own moral code.
In the search results provided, there were some novel recommendations about villains and cheating protagonists. Among them," The Great Villain: Let the Female Lead Save Me in the Finale " and " Greetings to the Cult Master " were two novels about the protagonist transmigrating into a great villain. These novels described how the protagonist would show his ability and charm after becoming the villain. In addition," The Strongest Villain System " and " Unlimited Deduction " were system novels about the protagonist cheating, telling the story of the protagonist displaying his powerful abilities in the system. Other than that, there were also some similar novels recommended, such as " The Villain's CEO Is Cheating " and " The Villain's Ex-Wife Is Deceiving Her Identity." In summary, if you are interested in novels with villains and cheating protagonists, you can try to read these recommended works.
There were a few novels about magic princesses fighting against villains that could be recommended. Among them were " The Princess Was Forced to Raise a Villain "," The Eldest Princess Smells Good After Being Forced to Raise a Villain Wolf Cub ", and " Dressed as a Villain Princess, She Was Forced to Raise a Sick Nation Master ". These novels covered elements such as ancient romance, transmigration, and counterattack. The story plots were all different.
If 'Sludge and Rippley' are characters from a fictional universe, their origin story might be related to the overall theme of that universe. For example, if it's a post - apocalyptic world, they could have emerged from the irradiated sludge left behind. It could also be that they are the result of a mad scientist's experiment gone wrong, where he was trying to create something entirely different but ended up with Sludge and Rippley.
In the given search results, there were a few novels that could be recommended. Among them,"Descent of the Demon Seed" was a story about the villain, the Great Demon King, who became a loyal dog and a pitiful little puppy. In addition,"How the Righteous and Villains Save Each Other (Part 1)" and "How the Righteous and Villains Save Each Other (Part 2)" were dramas about superheroes. In addition,"Saving the Poor Villain" was a criminal investigation novel that told the story of Jiang Shangxue becoming the villain's stepmother. These novels were all completed and could satisfy the readers 'needs for decent vs villain stories.
Well, if we assume they are from a magical world, then magic spells or enchanted items could be key elements in their origin story. Maybe there was a powerful wizard who accidentally summoned them while trying to do something else. Or it could be that they are part of a prophecy, and their origin is tied to the fulfillment of that prophecy. There could also be a connection to a special place, like a hidden grotto where they first came to be.
One common theme is the struggle between good and evil. The hero represents all that is good, like justice and kindness, while the villain stands for greed, power - hunger or malice. Another theme can be redemption. Sometimes the villain has a chance to turn good, or the hero might face a moral dilemma that tests his own 'hero - ness'. Also, the theme of sacrifice often comes up, where the hero might have to give up something precious to defeat the villain.
In 'hero academia sludge fanfiction', you might consider a story where the sludge is actually a misunderstood entity. It was once a normal substance but got corrupted by some evil force. A hero could try to purify the sludge instead of just fighting it. They might have to go on a quest to find the source of the corruption and in the process, learn more about the true nature of the sludge.