One idea could be a vampire character who is drawn to the power of the One Ring. Maybe this vampire, being a creature of the night and often associated with darkness and power -hunger, sees the ring as a means to gain ultimate power in Middle - earth. For characters, you could have a half - vampire, half - elf who struggles with their dual nature while being caught in the events related to the ring.
Perhaps the One Ring could have an unexpected reaction to Naruto's chakra. It could either be attracted to it or repelled. This could create an interesting plot where Naruto has to deal with the power of the Ring while also trying to find a way back to his own world.
To write a good vampire Lord of the Rings crossover fanfiction, you need to focus on character development. If you're introducing a vampire lord, make him a complex character. Give him motives that are more than just 'I want to rule the world'. Maybe he has a tragic past that led him to his current state. Also, make sure the language you use fits the tone of both worlds. The Lord of the Rings has a very specific, almost archaic style of speaking in places, and your vampire characters should also have a voice that is consistent with their nature. And don't forget about the pacing. You don't want to rush the story, especially when it comes to the big moments like battles or revelations about the ring.
Well, often there's the element of the vampires being outsiders in Middle - earth. They usually have their own powers and motives that are different from the normal LOTR characters. For example, they might be interested in the power of the One Ring for their own reasons, like using it to enhance their vampiric abilities or gain more control over other beings.
One idea could be that the Dragonborn from Skyrim somehow ends up in Middle - earth. Maybe they are mistaken for a powerful wizard due to their Thu'um abilities. Another plot could involve the One Ring being found in Skyrim and the different factions vying for its power, just like in Middle - earth. A third interesting plot would be characters from Lord of the Rings traveling to Skyrim and having to deal with the cold, the dragons, and the political unrest there.
One idea could be that the characters from Middle - earth accidentally stumble into Narnia through a magical portal. For example, Aragorn and Legolas could find themselves in the middle of the Narnian forest and team up with the Narnians to fight a common enemy, like an ancient evil that threatens both worlds.
One idea could be that the vampires from Twilight are drawn to the power of the One Ring. They might see it as a source of great power that could enhance their abilities. Another plot could involve a character from Twilight getting transported to Middle - earth and having to adapt to the new world while also dealing with the threat of Sauron. Or perhaps the werewolves from Twilight could form an alliance with the Ents in Middle - earth, as they both have a connection to nature.
One idea could be that Bilbo Baggins discovers a hidden relic during his adventures in 'The Hobbit' that later becomes crucial in the fight against Sauron in 'The Lord of the Rings'.
A crossover with the Star Wars universe would also be cool. The Jedi could be like the wizards in Middle - earth. Maybe Aragorn could learn some lightsaber skills from the Jedi and use them against the orcs. And the Force could have an interesting interaction with the magic in Middle - earth.
One idea is that Dracula is drawn to Middle - earth because of the power of the Rings. He believes that he can use their power to enhance his vampiric abilities. He tries to infiltrate the Fellowship to get closer to the One Ring. Another plot could be that Dracula has a history with some of the dark forces in Middle - earth, like the Nazgûl. They were once his allies or enemies in a different time, and this connection affects how he interacts with the events of the Lord of the Rings.
One idea could be that the Jedi and the Fellowship team up. The Jedi's use of the Force could be combined with the magic in Middle - earth. For example, they could fight against a common enemy like Sauron who has somehow gained control over some Sith artifacts, leading to a dark and powerful force in Middle - earth that both groups must combat.