A connection could be made through a shared interest in immortality. In the Harry Potter universe, there are things like the Philosopher's Stone that can grant immortality, and Orochimaru is constantly seeking ways to cheat death in his own world. A fanfiction could explore how Orochimaru hears about the Philosopher's Stone and tries to get his hands on it, which would bring him into conflict with the Harry Potter characters.
Well, one possible plot could be that Orochimaru somehow finds his way into the Harry Potter universe. He might be interested in the unique magic there, like the Elder Wand or the Philosopher's Stone. He could try to use his ninja skills and devious ways to steal these powerful magical items, and Harry and his friends would have to stop him using their own magic.
There could be a conflict between Harry and the existing wizarding order. The Ministry of Magic might view Harry as a threat because of his connection to Orochimaru. They would be worried that he might bring dark magic into the wizarding world. Harry would then have to fight against the prejudice and suspicion of the wizarding community, while also trying to figure out his own identity and loyalties.
One possible way could be in a crossover fanfiction where the magic systems of the Harry Potter universe and the ninja world of Orochimaru are combined. For example, Orochimaru might be interested in the magic of the Harry Potter world and try to study it. Maybe he could see the magic there as a new source of power or knowledge. Another aspect could be a character - perhaps a wizard - being sent to the Naruto world and having an encounter with Orochimaru, and through that, a connection between the two universes is established.
There's no evidence in the official Naruto or Harry Potter works that Orochimaru is a Harry Potter fanfic. But fanfiction is all about creativity and bending the rules. If someone were to write such a fanfic, Orochimaru could be written as a character who has somehow discovered the Harry Potter books or movies in his world. He could be envious of the power of the wizards, or he could see opportunities to learn new forms of magic. It would be a very unique take on both franchises, but again, this is all in the world of fan - created content.
One interesting idea in 'Harry Potter' fanfiction is the concept of alternate universes. For example, a fanfic might explore what would happen if Harry was sorted into Slytherin instead of Gryffindor. This could lead to a completely different set of relationships and storylines. Another idea could be time - travel fanfics where characters go back in time to change certain events in the wizarding world's history. It adds a whole new layer of complexity and intrigue to the original story.
One creative idea is time - travel fanfictions. For example, a character might go back in time to prevent certain tragedies from happening in the 'Harry Potter' story. Another idea is crossovers, like 'Harry Potter' and 'Lord of the Rings' crossovers, where characters from both universes interact.
One idea could be a story about what happens to the characters after the events of the original series. For example, exploring how Harry and Ginny raise their children and the new challenges they face in a post - Voldemort wizarding world. Another idea is to create a fanfiction set in an alternate universe where the sorting hat makes different decisions for the main characters. So, Hermione could be in Slytherin instead of Gryffindor, which would completely change her relationships and the storylines. Also, a story focusing on the backstories of the minor characters like Neville's parents or Luna's family would be really interesting.
How about a fanfiction where Orochimaru is transported to a different dimension where ninjutsu doesn't exist? He has to adapt and use his wits and knowledge in a completely new way. This would be a great way to explore his character without any adult themes. Or a story where Orochimaru tries to atone for his past sins by helping to rebuild a village that he once destroyed, showing a different side of his complex character.
Well, perhaps the OC son of Orochimaru could be in a situation where he is forced to choose between following his father's evil ways or siding with the ninja world to stop Orochimaru once and for all. He could have a unique ability, say, the power to communicate with all kinds of snakes and use this to his advantage in battles or in diplomatic situations. He might also meet some old enemies of Orochimaru who initially distrust him but then come to see his potential for good.
Some unique ideas could be that baby Harry has a special bond with magical creatures from a very young age. For instance, he might be able to communicate with Hedwig even as a baby, through some kind of magical telepathy. This could set up a whole different dynamic in the story.