A possible plot is that an ancient vampire artifact has been found in the ninja world. Naruto, being curious and always in the middle of things, gets involved. This artifact has the power to either grant immortality or destroy all vampires. The vampires want it to ensure their survival, and the ninjas fear it will disrupt the balance. Naruto must figure out what to do with the artifact while also dealing with a vampire who has befriended him and is trying to sway his decision.
A plot could revolve around Naruto using his Rinnegan powers to fight against an evil vampire clan that is threatening the Hidden Leaf Village. He might discover that the Rinnegan has some special abilities that are particularly effective against vampires, like being able to see their true forms even when they are hidden or being able to nullify their hypnotic powers.
One unique plot idea could be Agent Naruto being sent on a mission to a modern - day world to stop a group of villains who are using ninja techniques for evil in a world not used to such powers. Another might be Agent Naruto having to team up with his own enemies from the Naruto universe, but in a different, more complex political setting within the fanfiction's world.
Perhaps there's a fanfiction where Naruto and Katara get transported to a different dimension. In this new world, they have to rely on each other completely to survive and find a way back home. They might face strange creatures and new forms of ninjutsu that they have to adapt to. This would really test their bond and show how well they can work together outside of their normal environments.
Another interesting plot is the soul - swap. Imagine Naruto and Sasuke swapping souls. They have to deal with living in each other's bodies and understanding each other's perspectives in a very literal way. It leads to some hilarious and also very heart - warming moments as they learn more about each other.
A great plot idea could be a moment in time when the veil between the living and the dead is thinnest. Ghosts start to appear and interact with the living characters in the Vampire Diaries world. Some of these ghosts could be old enemies or friends, and their presence stirs up a lot of emotions. Another could be a moment in time when a powerful spellcaster tries to rewrite the history of Mystic Falls, and the main characters have to stop them before everything they know is changed forever. And then there's the idea of a moment in time when a character discovers they have a hidden power that has been dormant all this time, and they have to quickly learn to control it to face an imminent threat.
A cool plot could be that a powerful vampire targets Naruto because of his unique chakra. Shinso gets involved as he senses something is wrong with Naruto. They discover that the vampire wants to use Naruto's chakra to break a curse on their clan. Shinso and Naruto must decide whether to help the vampire or fight against it.
Well, there could be a plot where Naruto is a half - vampire. His mother was a human and his father was a vampire. Hinata is drawn to his unique nature. They end up on a journey to discover more about Naruto's vampire heritage. On this journey, they encounter different vampire clans. Some are friendly and some are hostile. Naruto has to use his vampire powers, like enhanced strength and the ability to see in the dark, to protect Hinata. And through all these adventures, their love for each other blossoms.
One idea could be a vampire OC who was turned before the apocalypse and has been hiding their true nature. But in the chaos of the walking dead world, they find it harder to keep their secret. They could use their vampire abilities like enhanced strength and speed to fight off the walkers, while also trying to avoid being discovered by the human survivors.
One idea could be a story where a character with both Shikotsumyaku and Sharingan abilities has to face a new, powerful enemy that can nullify their individual powers. So they must find a way to combine their abilities in an unexpected way to defeat the foe.
One idea could be that Naruto is sent on a mission to infiltrate a hidden village that is suspected of creating a new and dangerous jutsu, much like the Impossible Missions in the movies. He has to disguise himself as a common traveler and gather intel without being detected by the village's powerful ninjas.