He could bring some of his unique spells from Hogwarts. His Patronus charm could be a very useful tool in the often - dark and dangerous Dresden Files world. It could help him fight off some of the nastier creatures there. On the other hand, the wizards in the Dresden Files might view him with suspicion at first, not knowing exactly where his loyalties lie.
His relationships would be different. He wouldn't have the same kind of friendships as he did at Hogwarts. Instead, he'd form more tenuous alliances based on mutual self - interest. His view of magic would expand greatly as he discovers the different types of magic users and creatures in the Dresden Files world. This new exposure would shape his character into someone more complex and adaptable.
One interesting crossover could be the use of magic systems. In the Dresden Files, magic is more gritty and has a cost, while in Harry Potter it's more structured. A fanfiction might explore what happens when a wizard from Harry Potter's world tries to use Dresden Files magic, or vice versa.
Severus Snape and Murphy from the Dresden Files. Snape has his cold, brooding exterior and complex past, while Murphy is a tough, no - nonsense police detective dealing with the supernatural. Their interactions could be very tense, with Snape looking down on Murphy's 'mundane' ways of dealing with magic at first, but later realizing she has her own strengths.
One interesting 'Harry Potter Dresden Files' fan fiction could be one that combines the magic systems of both. For example, a story where Harry Potter and his friends encounter a problem that can only be solved by using Dresden's more gritty and street - wise approach to magic. Maybe they have to deal with a dark wizard who is using a blend of muggle - influenced dark magic that is more in line with the Dresden Files universe.
One idea could be that Harry Potter accidentally travels to the world of the Dresden Files. He could meet Harry Dresden and they team up to fight a dark magic threat that is affecting both their worlds. Maybe a powerful dark wizard from the Potterverse has found a way to use the magic from the Dresden Files world to enhance their power.
Naruto would probably befriend Harry Potter and his friends easily. He has a very friendly and outgoing personality. He could teach them about chakra and how it's different from magic. And in return, the Hogwarts students could show him all the cool spells and magical creatures. It would be a really interesting cultural exchange of sorts between the ninja world and the wizarding world.
In the Pokemon world, Harry Potter would be quite an anomaly. His magic could potentially disrupt the balance of the Pokemon universe. For example, he could use the Imperius Curse on a powerful Pokemon to make it do his bidding, which would be a huge advantage in battles. However, he would also face challenges as the Pokemon world has its own set of rules and powers. He might struggle to understand the concept of Pokemon evolution at first, thinking it's some sort of dark magic.
Well, he might use his magic to interact with Digimons in unique ways. For example, he could use spells to heal injured Digimons or to communicate with them more directly. His wizarding skills would surely give him an edge in this strange new world.
Well, in the original Harry Potter, magic is often about waving a wand and saying a spell. But in the Dresden Files, it's more about willpower and knowledge of the supernatural. In fanfiction, they might blend these. For example, a character might use a Harry Potter spell but with the added requirement of Dresden Files - style willpower.
He might use his magic to communicate with Pokemon in unique ways. For example, he could use a spell to understand their language. He would probably be amazed by the variety of Pokemon and their different abilities. And he may try to find some similarities between the magical creatures in his world and Pokemon.