Another approach would be to set it in a post - apocalyptic version of the Harry Potter world where the Terminators have already taken over most of the Muggle world. The wizards are the last hope. They would need to combine their knowledge of magic with any remaining Muggle technology they can find. Harry and his friends could train a group of young wizards to be like a wizard - Terminator hybrid fighting force. There would be a lot of scope for character development and exciting battles as they try to reclaim their world from the Terminators.
One way could be to start with Harry finding a book about Smaug in the Hogwarts library. He becomes so intrigued that he starts to have dreams about the dragon. Then, as the story progresses, he might use his magic to create a portal to the world where Smaug exists and tries to communicate with him.
To write such fanfiction, you could start by creating a crossover point. Maybe a portal opens between the Kryptonian world and the wizarding world. Then, characters from both sides start to interact. A Kryptonian could be amazed by magic and try to learn it, while wizards could be in awe of the Kryptonian's raw power. You'd have to balance the two different power systems and cultures so that the story makes sense.
Yes, it is a rather novel concept. It could mean that someone has created a fan - made story where the world of Harry Potter intersects with the Terminator universe. For example, perhaps the Dementors could be seen as a bit like the Terminators in some ways, with their cold and relentless pursuit of their prey.
One way could be to give Harry a more mysterious and aloof side like Tobi. Maybe he starts using illusions or misdirection in battles at Hogwarts, similar to how Tobi uses his Sharingan abilities. He could also adopt Tobi's habit of speaking in riddles, making his classmates and teachers wonder what he's really thinking.
You could write it by making Harry a chosen one in the Greek god world too. Maybe he has to stop an evil force that threatens both the wizarding world and the world of the Greek gods. He could get help from the Greek heroes like Hercules and use his magic to assist them in battles.
In theory, it is possible in fanfiction. One way could be through time - travel magic. Harry could discover a powerful time - turning spell that allows him to go back in time to the moment before his parents' deaths. He would then use his skills and knowledge from his own time to fight off Voldemort and save them. For example, he might use advanced defensive spells he learned at Hogwarts to counter Voldemort's attacks.
In a Naruto becomes a Terminator fanfiction, it could start with some sort of time - travel or interdimensional rift. Maybe a jutsu gone wrong sends Naruto to a world where the Terminator technology exists. Then, Naruto, with his ninja skills and strong will, might adapt to the new environment. He could use his chakra in unique ways combined with the advanced weaponry of the Terminator world.
Well, it's a really wild concept. In theory, it could be possible. Maybe Harry Potter, with his magic skills from his own world, could find himself in the Highschool DxD universe and for some reason decides to take Rias under his wing. He could teach her some unique magic tricks that are different from the devil magic in her world. But it would be really challenging to blend the two very different universes' magic systems and storylines in a believable way.
It should start with a deep understanding of what makes each franchise special. For Harry Potter, it's the magic system, the houses at Hogwarts, and the battle against Voldemort. For One Piece, it's the Grand Line, the Devil Fruits, and the search for the One Piece. In the fanfiction, these elements should be carefully incorporated. Maybe have a story where some of the Hogwarts students are kidnapped and end up in the One Piece world, and the Straw Hat Pirates help them get back home while also learning about magic along the way. This way, both franchises are respected and it creates an exciting new story.
One way could be to make it a comical misunderstanding. For example, Harry is forced by a magical prank gone wrong to 'suck' on a lemon drop that Snape always has, and it's all just a big, silly situation that makes for a humorous moment between their otherwise tense relationship.