Another aspect to consider is the relationship between vampires and the wizarding world in the fanfiction. If vampires are seen as outcasts, Harry might have to fight not only Voldemort but also the prejudice of the wizarding community. However, this could also make him more determined to defeat Voldemort, to prove that he's still a force for good despite his vampiric nature.
In a fanfiction scenario, Harry might have a different kind of magic due to being a vampire. This could either make Voldemort more interested in him, wanting to study or steal his power. Or it could make Voldemort more cautious as he doesn't fully understand this new version of Harry. Harry could also use his vampire charm or mind - control abilities (if he has them) to manipulate Voldemort's followers and turn them against him.
Well, one possibility is that as a vampire, Harry would have enhanced strength and speed. When meeting Voldemort, he could use these new abilities to his advantage. Maybe he'd be able to dodge Voldemort's curses more easily and counter - attack in ways that a normal wizard couldn't. For example, his vampire fangs could be used as a weapon in close - combat if Voldemort got too near.
In such a fanfiction, Harry might be tortured for information about the Order of the Phoenix. Voldemort could try to turn Harry to the dark side, using threats against his friends.
In such a fanfiction, Harry might go to Voldemort to try and reason with him. Maybe he believes there's a chance to end the war without more bloodshed. He could offer Voldemort a way out, like exile instead of death.
Well, it could be that God appears to Harry in a moment of great despair. He might show Harry the true nature of life and death in the wizarding world. Harry could learn about the deeper meaning behind the magic he wields and how it is all part of a greater plan designed by God. God could also guide Harry on how to use his powers more morally and justly, not just for the sake of defeating the Dark Lord but also for the betterment of the entire wizarding community.
Well, perhaps Harry Potter could use his magic against Shendu's dark powers. For example, he might try to counter Shendu's spells with his own powerful incantations like Expelliarmus. It would be an epic battle of magic from two different fictional universes.
One possibility is that Medusa is somehow brought into the Hogwarts grounds. This would cause chaos among the students and teachers. Harry, being the hero he is, would step up. He might research ancient spells and potions to deal with Medusa. He could also enlist the help of his friends like Hermione, who would dig into the library to find any information about Medusa in the wizarding world's history, and Ron, who would be there for moral support and also to help in any practical ways they could come up with.
One possibility is that Harry would learn the real motives behind some of the actions of the Hogwarts teachers. Maybe Dumbledore had some other reasons for keeping certain secrets from him all along. It could also be that the truth about the relationship between different magical creatures and wizards is revealed, like why some were always seen as more dangerous than they really were.
Well, it could be that the Cullens and Harry Potter team up against a common enemy. For example, a dark wizard who has some sort of connection to vampires. Harry could learn about the Cullens' way of life and they could learn about the wizarding world. There might be a cultural exchange of sorts, with Harry showing them things like butterbeer and the Cullens introducing him to their vampire traditions, if they have any.
Well, it could be really interesting. Maybe Anubis takes Harry on a journey through the Egyptian underworld in the fanfiction. Harry, being used to the wizarding world of Hogwarts, would be exposed to a whole new set of rules and magic in this strange underworld. He could meet other Egyptian deities and gain knowledge that would be useful in his own magical battles back in the UK.
There could be a situation where Nagini is in a weakened state for some reason. Harry, being the hero he is, might face an internal struggle. On one hand, he knows Nagini is Voldemort's pet and has been involved in many evil deeds. But on the other hand, he might see her as a victim of Voldemort's dark magic. So he could either try to kill her or try to free her from Voldemort's control.
In this fanfiction, Harry could learn ancient magic directly from the founders. Maybe he'd get special training from Godric Gryffindor in courage - based spells, or study potion - making secrets from Helga Hufflepuff.