Obviously, Hadrian is one of the main characters. He is the version of Harry Potter with a different name. Then, we might still see characters like Hermione and Ron. They would interact with Hadrian in different ways compared to how they interacted with Harry. Their relationships could be more complex or different in nature.
One interesting plotline could be how Hadrian deals with the expectations of the wizarding world differently from Harry. Maybe he uses his knowledge of the future in a more proactive way to change things for the better in Hogwarts, like reforming the House system.
Hadrian is the central figure in most of these fanfictions. He is usually depicted as a more complex or altered version of Harry. Voldemort can also be a significant character, as the main antagonist in the Harry Potter universe. In some fanfictions, new characters are introduced who play important roles in Hadrian's life, such as a mysterious mentor or a rival wizard. Snape might also be there, his relationship with Hadrian being a key aspect in some stories.
One great 'Harry Potter Hadrian' fanfiction is 'The Boy Who Lived Again'. It has an interesting take on Hadrian's character, showing his growth and development in a unique way. Another one could be 'Hadrian Potter and the Secrets of Hogwarts' which delves deep into the secrets of the school from Hadrian's perspective.
Well, Harry could be really confused at first. Ouran is a very different world from Hogwarts. He might be shocked by the opulence of Ouran Academy and the strange club system there. Maybe he'd try to find a way to fit in while still being true to his wizard self.
Another plotline might involve characters from the Harry Potter series using Hadrian's Wall as a place of refuge or a strategic location during a battle against dark forces. The wall could have protective enchantments placed on it long ago, and the characters have to figure out how to use them to their advantage. For example, it could be a place where they gather to plan their defense against Voldemort or other threats. The wall's historical and magical significance could be explored in depth, like how it was built by Muggles but has now become a part of the wizarding world's defenses.
Well, it depends on how the fanfic defines 'powerful'. If being a demigod in that fanfic means having extraordinary magical abilities along with some demigod - like traits such as enhanced physical strength or a special connection to certain forces, then Hadrian Potter could be considered a powerful demigod. However, different readers might have different interpretations of what makes a character truly 'powerful' in this context.
Hermione Granger could also be a prominent character. She would use her vast knowledge to research about the history and magic associated with the wall. For instance, she might be the one to find ancient texts that mention the wall's significance in the wizarding world. And then she would share this knowledge with Harry and Ron to start an adventure related to it.
He might meet international aurors. These are highly skilled wizards from different countries who are experts in dark wizard catching. They could teach Harry some new combat spells.