Another aspect could be the settings. A fanfiction could merge Hogwarts with the streets of Chicago from the Dresden Files. Picture Hogwarts students exploring the dangerous alleys of Chicago filled with all kinds of supernatural beings that Dresden has to deal with on a regular basis. It would be a whole new adventure for both universes' characters.
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.
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.
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.
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.
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.
First, you need to be really familiar with both universes. Read all the Harry Potter books and watch the movies, and also read the Dresden Files series. Then, think about a concept that would bring the two together in an interesting way. It could be a simple idea like a character exchange or a more complex one like a merged magic system. After that, start with an outline of your story, including the main characters, the plot, and the setting.
There could also be a scenario where Harry Potter has to face the Joker in a psychological battle. Since Harry has faced his own share of dark forces, the Joker's mind - games could be a new and different kind of challenge for him. Harry would have to use his courage and the skills he learned at Hogwarts to outwit the Joker.
A really interesting crossover is when the magic of Harry Potter is used to enhance the gadgets in Kingsman. For example, in some fanfics, they create wands that can also function as Kingsman umbrellas, with the ability to both shoot spells and act as a shield or a parachute. It's a cool blend of the two worlds' technologies.
Another interesting crossover is when the Deathly Hallows are somehow connected to the tailed beasts in Naruto. It's a unique take that combines the powerful artifacts from Harry Potter with the equally powerful beasts from Naruto. This often leads to a story full of high - stakes battles and unexpected alliances.
One interesting crossover could be the use of magic in the Warframe universe. For example, a Harry Potter character might bring spells like 'Accio' to retrieve items in the middle of a Warframe mission. Or perhaps a Warframe with magical abilities inspired by Hogwarts magic.
One interesting crossover could be a Creepypasta character infiltrating Hogwarts. For example, Jeff the Killer could be lurking in the Forbidden Forest, adding a terrifying element to the otherwise magical place. It would be a really spooky scenario as students unknowingly get closer to this dangerous figure during their adventures in the forest.