One possible plot is that there is a breach between the Naruto universe and the Hellsing universe. This causes chaos as demons from Hellsing start to invade Konoha. Naruto, being the hero, tries to figure out how to stop them. Alucard arrives, not entirely as an ally at first. But as they both realize the common threat, they join forces. Naruto learns about the different nature of the enemies from Alucard and adapts his ninja skills accordingly.
Sakura could also be a main character. She's a strong ninja in her own right. In a fanfiction like this, she could be involved in treating the injured when the Hellsing - related chaos starts. Maybe she also tries to understand the unique physiology of Alucard. And Integra from Hellsing. As the head of the Hellsing organization, she could be the one trying to establish some sort of order between the two worlds.
The plot could be that Naruto is somehow transported to the Hellsing universe. He starts off as an outsider but quickly proves his worth. His rasengan could be adapted to be effective against vampires, perhaps by infusing it with holy water or some other vampire - weakening element. Naruto's presence could also introduce a new dynamic to the relationships within the Hellsing organization, and he might even form an unexpected bond with Seras Victoria as they both have a strong sense of loyalty and a desire to protect the innocent.
Perhaps the fanfiction could focus on Naruto's adjustment to the new environment in Konoha. He'd have to get used to the different training facilities, local customs among the ninja clans, and the overall layout of the village. For example, he might struggle at first to find his way around the various training grounds and meet - up spots for ninja teams. But as he explores, he discovers hidden gems in the village and forms closer bonds with the villagers.
It could also be a sparring session gone wrong. Naruto might be training with the Konoha 12, but his new and powerful techniques are too intense. This causes the others to feel threatened and they end up in a full - on fight. Naruto would then have to control his power and show his friends that he doesn't mean to harm them.
Well, it could be about Naruto being wrongly accused and turning against Konoha. Maybe some false evidence is planted against him, making the villagers see him as a threat. So he decides to oppose Konoha to clear his name.
In a 'naruto conquers konoha fanfiction', perhaps Naruto could be pushed to the edge by the corrupt system in Konoha. He might decide to take over to bring real change. He could use his powerful jutsu and the loyalty of his friends to overthrow the old regime and install a more just rule.
In a dark 'naruto executed by konoha fanfiction', it could be that Konoha, fearing Naruto's power, decides to execute him. Maybe they believe false rumors spread about him. It's a very tragic and dark take on the Naruto universe.
One possible plot could be that Naruto and his team are sent to the Hellsing universe on a mission. They encounter Alucard and his group. Naruto, with his ninja skills and strong will, might initially be seen as a threat by the Hellsing crew. But as they learn about his world and his fight for peace, they start to work together. Maybe Naruto tries to understand Alucard's vampiric nature and in turn, Alucard is intrigued by Naruto's chakra and jutsu. Together, they could face a new threat that is endangering both their universes.
One possible plot could be that Konoha Village has to reclaim Naruto after he has been lost in a mysterious dimension. The villagers might realize his importance more than ever and send out a team of elite ninjas, including Sasuke and Sakura perhaps. They would face numerous challenges in this other dimension, like strange new jutsus and powerful enemies. Along the way, they would also discover new things about Naruto's powers that even he wasn't aware of.
Well, perhaps Naruto could be framed for a crime in Konoha and then be forced to leave as an assassin. He might start working for an enemy village at first, but then gradually realizes that there's a deeper conspiracy behind his framing. So he decides to clear his name and also protect Konoha in the end.