A different plot could be that a curse has been placed on both Naruto and Seras. They start having visions of each other's past traumas. As they try to figure out how to break the curse, they discover that it was placed by an old enemy of both the ninja clans and the Hellsing organization. To break it, they need to find a magical artifact hidden in a dangerous dimension that is guarded by powerful demons and rogue ninjas.
A possible plot could involve Schrodinger being sent on a mission with Seras by the Hellsing Organization. During the mission, they face a powerful enemy that forces them to rely on each other's unique abilities. As they work together, a deeper understanding and an unexpected bond form between them. This could explore how their different natures, Schrodinger's quantum - like existence and Seras' vampiric nature, interact and complement each other in the face of danger.
One interesting idea could be their unique relationship dynamic. Seras is a vampire and Pip is a human, so exploring how they bridge the gap between their two worlds can be really engaging.
One idea could be a crossover where Naruto is somehow transported to the Hellsing universe and meets Seras. Maybe Naruto's unique powers, like his shadow clones, could be used in battles against the vampires in the Hellsing world. Seras, with her vampire abilities, might initially be seen as an enemy to Naruto but they could end up teaming up.
One plot idea could be Naruto being transported to the Hellsing universe and having to deal with the vampires there using his ninja skills. He might form an alliance with the Hellsing Organization and help them fight against a new, powerful vampire threat.
One idea could be a crossover where Naruto's world is invaded by supernatural forces from the Hellsing universe and Integra has to team up with Naruto to fight them. Naruto's ninja skills combined with Integra's leadership and the power of the Hellsing organization would make for an exciting story.
One interesting plot idea could be a story where Seras and Integra have to team up against a new and powerful vampire threat. They start to understand each other on a deeper level during their battles and form a stronger bond.
Naruto's ability to use chakra could enhance Seras' vampire powers. For example, he could use his chakra control to help Seras better regulate her own energy, which might make her faster and stronger. Seras, on the other hand, could use her vampiric senses to help Naruto in combat. Her enhanced hearing and sight could detect hidden enemies that Naruto might miss with his normal senses.
Another idea is a story where some of the Naruto villains team up with the antagonists from Hellsing. Orochimaru might be interested in the vampire technology or the powers of the vampires in Hellsing. He could try to use it to further his own goals, and this could lead to a complex and action - packed plot with both Naruto and Hellsing characters caught in the middle.
Perhaps a story where Pip gets injured and Seras has to take care of him. During this time, they have long conversations about their pasts, their hopes, and dreams, which brings them closer. Seras discovers new aspects of Pip's personality that she hadn't noticed before.
Maybe there's a rift in the multiverse that connects the two worlds. Integra discovers Danny's powers and tries to recruit him to help in the fight against the vampires. Danny, being a hero in his own world, is hesitant at first but realizes the importance of cooperation when he sees the scale of the vampire threat in the Hellsing universe. He could use his intangibility and flight to outmaneuver the vampires while Alucard and Seras provide the heavy - hitting attacks.