The plot could involve Tsukune being turned into a vampire against his will. He would then have to come to terms with his new identity. He might seek a way to reverse the transformation, leading him on a journey to find a cure. Along the way, he could meet other vampires who either help or hinder his quest, and he would also have to deal with the fact that his relationships with his non - vampire friends are now in jeopardy.
Perhaps in the fanfiction, Tsukune becomes a vampire and discovers a whole new world within the vampire society. He could learn about the different vampire clans and their politics. He may even fall in love with a vampire, which would further complicate his situation as he still has feelings for his human friends. His transformation could also be a part of a grander scheme by a powerful vampire who has plans for Tsukune.
One possibility could be that Tsukune's death is a sacrifice to save his friends. In the Rosario Vampire world, he has made many friends and perhaps in the fanfiction, a powerful enemy threatens them all. Tsukune, being the selfless character he is, might give his life to ensure their safety. For example, if a dark and ancient vampire or a powerful monster attacks the school, Tsukune could use his unique powers (a combination of human and vampire abilities) in a final, all - out attack that costs him his life.
Perhaps Tsukune is turned into a vampire as part of a ritual gone wrong. In the fanfiction, he could be the key to some prophecy that the vampires are trying to fulfill. As he turns, he starts to have visions related to the prophecy. He then has to decide whether to embrace his new vampire self or fight against it to protect his non - vampire friends.
The plot could involve Naruto somehow getting cursed by Slenderman. This curse starts to affect his ninja abilities, like his chakra control. As he tries to figure out what's wrong, he discovers the connection to Slenderman. He then has to journey into the dark and mysterious places where Slenderman lurks to break the curse. Along the way, he might meet some of Slenderman's minions and have to fight them using his unique jutsu.
Well, in a Naruto becomes a hollow fanfiction, perhaps the chakra system in Naruto gets corrupted and turns him into a hollow. His appearance would change to something more menacing. He might start to crave spiritual energy instead of normal food. His relationships with other characters would be on edge. For example, his bond with his teacher Kakashi would be tested as Kakashi tries to figure out how to reverse the transformation or at least help Naruto co - exist with his new hollow self.
In a Naruto - becomes - a - teacher fanfiction, Naruto could focus on teaching his students about the value of friendship and teamwork. He might organize team - building exercises that are actually dangerous ninja missions. His students would learn to rely on each other, just as he did with his own team. He could also share stories about his adventures with the Akatsuki, making sure his students understand the threats that still exist in the ninja world.
Well, it could involve Issei discovering some ancient dragon magic. Maybe he stumbles upon a dragon's lair and is blessed with dragon powers. He might start to have dragon - like instincts, like a strong urge to hoard treasures or protect a certain territory.
In a Naruto becomes a hermit fanfiction, he could be on a journey to find a deeper meaning to his existence. He might abandon his fame and status. Living as a hermit, he'd have to fend for himself, which would make him stronger in a different way. He could start to understand the true essence of chakra in a more spiritual sense, away from the battles and politics of the shinobi villages.
The plot could also involve Naruto being transported to the world of Sparda. There, he has to learn the ways of that world to survive. He might meet characters similar to those in his own world, but with different abilities. And he could form new alliances, like teaming up with demons who oppose the main evil forces in the Sparda universe.
One possibility could be that Naruto discovers a new side of Himawari. Maybe she shows an unexpected talent for ninjutsu that Naruto is really impressed by. This could lead to Naruto becoming her biggest supporter and fan, constantly cheering her on during her training sessions.
Well, it could be that Naruto discovers the tales of Gilgamesh's power and heroics. Maybe he starts to idolize Gilgamesh's confidence and his unwavering belief in his own supremacy. Naruto might then try to incorporate some of Gilgamesh's leadership style into his own way of leading his comrades in the Hidden Leaf Village.