In this 'naruto the quirky villain fanfiction', the villain could be a master of illusions but in a very unorthodox way. Instead of creating fearsome or menacing illusions, they create really absurd ones like a world filled with giant rubber ducks. The villain could also be a talking animal that has somehow gained ninja powers and uses them in the most unpredictable ways. They might befriend some of the minor characters in Naruto and use them for their own comical and mischievous plans.
I think Orochimaru could also fit the bill. His experiments on himself and others are really out there. He's constantly looking for ways to gain more power and immortality in some really strange and unethical ways. His snake - like features and his ability to shed his skin like a snake add to his quirkiness. He's not your typical, straightforward villain and has a lot of idiosyncrasies that could be played up in a fanfiction.
One idea could be that the female villain initially tries to use Naruto to further her evil plans but ends up falling in love with him. For example, she might pretend to befriend him to get closer to some powerful jutsu he has access to. But as she spends time with Naruto, she sees his unwavering determination and kindness, which starts to change her perspective. Another plot could be that Naruto has to team up with the female villain against a greater threat. During their time together, they have to overcome their differences and learn to trust each other.
One idea could be to explore the backstory of Orochimaru in more depth. Maybe show his early days in the Hidden Leaf Village and what led him to become so obsessed with immortality and dark jutsu.
One idea could be that Tony Stark is brainwashed by a powerful enemy. This enemy uses some advanced technology to manipulate his mind, turning him into a villain who starts attacking his former allies. He might use his Iron Man suits in new and devious ways against the Avengers.
One idea could be exploring the backstories of the villains in more depth. For example, how did Shigaraki develop his nihilistic view? Another could be a 'what if' scenario, like what if the villains were given a chance at redemption early on. Maybe a story where they form an uneasy alliance with some of the heroes for a common greater threat.
One idea could be that the villain somehow gets amnesia and Batman has to decide whether to use this to his advantage or try to rehabilitate the villain. Another could be a scenario where the villain and Batman are forced to team up against a greater threat that endangers Gotham. Maybe a new, extremely powerful villain emerges and Batman realizes he needs the knowledge and skills of his regular foes to stop it.
A plot idea could be that Naruto discovers a new, ancient form of chakra that has been lost for centuries. He then has to train to master this chakra while also dealing with the political implications within the Hidden Leaf Village. Some elders might be against him exploring this new power for fear of the unknown, but Naruto, being Naruto, is determined to master it for the good of the village.
One idea could be that the events of 9/11 somehow influence the Hidden Leaf Village. For example, they might tighten security and Naruto could be part of a new team in charge of protecting the village from potential outside threats inspired by the real - world event. Another plot could involve characters from Naruto trying to understand the concept of such a large - scale tragedy and how they can prevent similar things in their own world.
A villain oc who is a half - human, half - beast hybrid. They were outcast from society because of their appearance and now seek revenge on all the villages. They have unique physical abilities due to their hybrid nature, like super strength and enhanced senses. Or perhaps a villain oc who is a former student of a great ninja but turned against their teachings. They create their own new and dangerous form of ninjutsu that goes against the traditional ways.
One idea could be that the villain has a change of heart after realizing Batman's true purpose in protecting Gotham. Maybe the villain has a personal experience that makes him see Batman in a new light. For example, his family is saved by Batman's actions indirectly, so he decides to return the favor when Batman is in a really tough situation.