A possible crossover could be in a battle - royale type of situation. Imagine Naruto and his ninja friends being thrown into the Hellsing universe and having to fight alongside or against Alucard and the other characters there. Another could be a story where Alucard somehow ends up in the Naruto universe and has to deal with the politics and power structures there, much like how he deals with the vampire hierarchy in his own world.
One crossover idea could be that Naruto's chakra system is somehow connected to Alucard's vampiric powers. Maybe there's a villain who wants to combine the two powers for some evil purpose. So Naruto and Alucard have to team up to stop this from happening. They would have to learn about each other's powers and work together, which would be really interesting as they come from such different backgrounds. Also, a crossover could involve Naruto teaching Alucard some of his ninja techniques in exchange for learning about Alucard's immortality and how it could be used to protect his village.
Maybe in the fanfiction, Fem Alucard is a rogue vampire in her own world and is on the run. She accidentally enters the Naruto universe. Naruto discovers her and initially mistakes her for a new kind of enemy. However, as he observes her, he realizes she is not all bad. Fem Alucard, in turn, is intrigued by Naruto's determination. They end up forming an alliance when a powerful foe from the Naruto world decides to use Fem Alucard's powers for their own evil purposes.
Well, one possibility could be that Naruto uses his ninja skills in the Monster Hunter world. For example, his shadow clone jutsu could be used to distract the huge monsters while he looks for their weak points. He might also learn some of the Monster Hunter's unique weapon techniques and combine them with his own combat style.
Perhaps the female Alucard is a threat to the Naruto world at first. She might be seen as an evil force because of her vampiric nature. But as the story progresses, she could learn about the values of the Naruto characters, like friendship and loyalty. And in turn, the Naruto characters could come to understand that she's not entirely bad and they could all work together against a greater evil that threatens both their worlds.
A possible crossover could be the ninja techniques being incorporated into the Airwolf combat scenarios. For instance, Naruto's Shadow Clone Jutsu could be used to confuse the enemies while Airwolf is in a dogfight.
Well, one similarity could be their extraordinary powers. Naruto has his chakra-based abilities like the Rasengan, while Alucard has his vampiric powers. They both can take on numerous foes at once. Naruto often battles groups of ninjas, and Alucard can face hordes of enemies with ease. Also, they both have a sense of loyalty. Naruto is loyal to his village, and Alucard is, in a way, loyal to his master or his own sense of justice.
The plot could involve Naruto having Alucard's powers and abilities, like his vampiric strength and regeneration. Maybe he uses these new powers to protect Konoha from a new kind of threat that normal ninja skills can't handle.
In this fanfiction, perhaps Naruto is the reincarnation of Alucard due to some ancient prophecy. His journey would then be about discovering his connection to Alucard. He could start having strange dreams about Alucard's past life and battles. As he uncovers more, he realizes he has to use Alucard's powers to save the ninja world from a new, powerful threat that only his combined Naruto and Alucard abilities can defeat.
The 'Naruto neglected Alucard' fanfiction could have a plot where Alucard is brought into the Naruto world by some mysterious force. However, the shinobi community is so focused on their own affairs like ninja wars, clan politics, and training that they simply overlook him. Alucard, feeling slighted, decides to use his vampiric powers and centuries - old knowledge to carve out his own place. He might first target the outcasts or those on the fringes of society, and as his influence grows, he starts to draw the attention of the more powerful Naruto characters, leading to a complex web of relationships and power struggles.
Well, it could be about Naruto having some of Alucard's powers. Maybe he has enhanced strength and speed like Alucard. And he could use these powers to protect Konoha in a new and unique way.
One possible plot could be that Naruto, during one of his travels, stumbles upon the world where Alucard exists. Alucard, being intrigued by Naruto's unique chakra, decides to test him. Naruto, on the other hand, sees Alucard as a powerful and somewhat mysterious figure. They could end up teaming up against a common enemy that threatens both their worlds, combining Naruto's ninja skills and Alucard's vampiric powers.