One way it could work is if there was a prophecy in both worlds that foretold of a hero from each realm coming together. Harry Potter, being the hero of the wizarding world, and Aquaman, the hero of Atlantis, are brought together by this prophecy. They start off not trusting each other, as they are so different. But as they face challenges together, like sea monsters attacking the coast near Hogwarts or dark wizards trying to steal treasures from Atlantis, they learn to respect and rely on each other, and their combined efforts save both worlds.
Aquaman's ability to control the sea could be used to create massive water - based defenses around Hogwarts. In return, Harry could use magic to give Aquaman the ability to breathe air indefinitely when he's on land for extended periods. Their powers could also combine in a more offensive way. For instance, Harry could use a levitation spell on Aquaman while he's in the water, allowing Aquaman to attack enemies from above the water surface with his enhanced speed and strength.
Well, in a 'Harry Potter son of Aquaman' fanfiction, the story could start with Harry being an outcast at Hogwarts because of his strange connection to the ocean. As he grows older, he realizes he can control water in ways other wizards can't. This leads to him being both feared and admired. He could then go on a quest to find out more about his father Aquaman and in the process, use his combined magical and Aquaman - like powers to defeat a dark force that threatens both the wizarding world and the underwater kingdom.
They would probably start off being a bit cautious of each other. Harry would be intrigued by Arthur's unique powers and his connection to the ocean. Arthur, on the other hand, would be curious about Harry's magic. They might exchange stories about their respective worlds at first, like Arthur telling Harry about Atlantis and Harry sharing tales of Hogwarts.
One way it could work is if the Asgardians had some connection to the wizarding world long ago. Mjolnir could be a powerful magical artifact in both worlds. Harry could be the chosen one to wield it in the wizarding context, similar to how Thor wields it in his world. He would then have to learn to control the hammer's power along with his own magic.
The main antagonist could be a dark wizard who has mastered water - based magic and has made a pact with a powerful sea monster. This dark wizard wants to rule both the wizarding world and the underwater world. He sees Harry Potter as a threat to his plans in the wizarding world and Aquaman as a hindrance in the underwater realm.
Harry would likely have a different sense of self - worth. Knowing he is the son of a powerful underwater hero like Aquaman, he would carry himself with more pride. He might also be more in tune with his emotions, as the ocean is often associated with depth of feeling. And his magical abilities could be enhanced in ways related to water, like creating more powerful water - based spells. He could also be more of a loner, as his unique heritage might make it hard for others to fully understand him.
A possible scenario is that Queen Elizabeth has a magical artifact that has been passed down through generations in the royal family. This artifact draws the attention of Harry Potter and his friends. They come to her palace to investigate, and she becomes involved in their adventures. She could offer them resources and protection in the Muggle world, while they introduce her to the wonders of the wizarding world.
Well, it could be really interesting. The Sharingan, with its abilities like seeing chakra and predicting movements, would be a wild addition to the Harry Potter universe. Maybe an OC with a Sharingan could use it to see through invisibility cloaks, as they're kind of like a form of concealment similar to genjutsu in Naruto. They could also potentially predict the spells that other wizards are about to cast, giving them an edge in duels.
Well, it could work by integrating the magic system of Harry Potter with the power of Susanoo. For instance, the wizards in the Harry Potter world could learn to harness Susanoo's power through their magic training. They might use spells to activate it, like 'Accio Susanoo' to summon it.
Well, it could start with the Hulk being magically summoned to Hogwarts. He'd be confused by all the magic around him. The Hogwarts professors would be both fascinated and worried about this strange, incredibly strong being. They'd try to communicate with him, but the Hulk might just roar in response. Harry and his friends could be the ones to eventually make a connection with the Hulk, maybe by showing him kindness instead of fear.