Another way is through a common enemy. Suppose there is a villain who has the ability to manipulate both magic and technology. This would force Fem Harry Potter and Superman to combine their forces. In the process of fighting this enemy, the two universes become more intertwined as they share resources, knowledge, and strategies to defeat the common foe.
The characters themselves can also be the means of merging. Superman, with his curiosity about different forms of power, might be drawn to the wizarding world. Fem Harry Potter, on the other hand, could be intrigued by Superman's super - powers. Their mutual interest in each other's abilities can start the process of bringing the two universes together. They might start working together to solve problems that affect both worlds, which gradually blurs the lines between the two universes.
In many fanfictions, magic is the key to merging the two universes. Fem Harry Potter's world of magic can act as a bridge. For example, a powerful spell might accidentally open a portal between the wizarding world and Metropolis, allowing the two to interact.
Some fanfictions merge the universes by having a shared event. Like in 'The Great Crossover Event', there is an event that draws characters from both the Harry Potter universe and the Yu - Gi - Oh universe together. Fem Harry Potter uses her magical skills, and she has to learn about the dueling system in Yu - Gi - Oh to participate. It's all about how these two different types of magic and combat styles interact with each other.
Writers often start by establishing how a fem Percy Jackson could end up in the Harry Potter universe. Maybe through a magical portal or some kind of cross - dimensional spell. Then they find ways to make her demigod powers interact with magic. For example, her ability to control water might have an unexpected effect on a magical water - based spell in Hogwarts.
In many fanfictions, they merge the universes through magical portals. For example, a spell in the 'Harry Potter' world might accidentally open a portal to the 'Btvs' universe where Angel exists. This allows characters from both to interact.
In these fanfictions, they often blend the two universes by having the fem Harry Potter use her magic in the Legend of Zelda world. For example, her spells can be used in combat or to solve puzzles, just like Link uses his items. The magical creatures from Harry Potter might also appear in Hyrule, like hippogriffs or house - elves, which adds a unique twist to the Zelda setting.
In many RWBY Space Marine fanfictions, they merge the two universes by having a portal or some sort of interdimensional rift. This allows the Space Marines to end up in the RWBY world. For example, in 'The Astartes of Remnant', a warp - like portal sucks in a group of Space Marines and drops them right into the middle of Vale.
One way they can merge is through character crossovers. For example, a character from Game of Thrones like Jon Snow could be transported into the Warhammer universe. He might find himself in the middle of a battle between different factions in Warhammer, using his skills learned in Westeros to survive. His sense of honor and leadership could also have an impact on the Warhammer characters he encounters.
In fanfiction, the magic in Harry Potter is more about spells and potions. Wizards learn specific incantations to produce magical effects. In Lord of the Rings, magic is more mysterious and often associated with the power of certain beings like Gandalf. So in a fem Harry Potter and Lord of the Rings crossover, the fem Harry might be confused by the more nebulous magic in Middle - earth at first.
In many fanfictions, the two universes merge through magical portals. For example, in some stories, a powerful spell in the Winx Club world accidentally creates a portal to the Pokemon world, allowing the characters to cross over.
In fanfiction, the two universes blend in multiple ways. The characters from Harry Potter can be put into Creepypasta - like situations. For instance, Harry might find himself in a situation where he has to face a entity that is not from the wizarding world but from a Creepypasta realm and has to use his magic in a new and untested way to survive. Also, the magic in Harry Potter can be warped to fit the spooky nature of Creepypasta. Spells could have unexpected and disturbing side - effects that are more in line with Creepypasta. The creatures in Harry Potter can also be made more menacing by borrowing elements from Creepypasta. For example, a Hippogriff could be made to look more like a nightmarish beast with Creepypasta - inspired features.
In some fanfictions, the merge happens when a powerful artifact from either universe is activated. This could be a Kamen Rider's belt or a powerful relic from Highschool DxD. When this happens, it creates a rift that pulls elements from one universe into the other. The characters then have to deal with the new and unexpected situations. For instance, the devils in DxD might be intrigued by the Kamen Rider technology and try to harness it for their own purposes.