Often, the wizard characters are curious about the Muggle girlfriend's world. They might ask her a lot of questions about Muggle technology like cars or mobile phones. And the Muggle girlfriend, in turn, is fascinated by magic, constantly asking for demonstrations.
The wizard characters might initially be very cautious. For example, Hermione would likely be the one to do a lot of research on Muggle UN representatives and how to best communicate with them. She would probably try to find common ground in terms of goals like world peace and protection of all beings, magical or not.
They might interact as allies. For instance, Itachi's combat skills and strategic mind could help Harry in battles against Voldemort's forces. Harry, in turn, could introduce Itachi to the magic of the wizarding world, like spells that could enhance Itachi's abilities further.
They interact in a mentor - mentee way in many stories. Oliver teaches Fem Harry about the finer points of Quidditch, like strategies and how to handle different broomsticks. As time goes on, they start to share more personal stories and feelings, which deepens their relationship. For example, Fem Harry might tell Oliver about her struggles with being different at Hogwarts, and he offers her support and advice from his own experiences as a Quidditch captain.
Often, Naruko and Harry might start as curious about each other's worlds. Naruko could be fascinated by magic wands and spells, while Harry might be intrigued by her chakra and ninja tools. They would exchange knowledge, like Naruko teaching Harry some basic ninja stealth moves, and Harry showing Naruko how to use a simple levitation charm.
Often, they interact with a lot of suspicion at first. Harry is used to a world of magic with rules and ethics, while Klaus is from a more cut - throat supernatural world. So, their first meetings usually involve sizing each other up. For instance, Klaus might see Harry as a potential pawn in his power games, while Harry would be cautious of Klaus's violent reputation.
They could interact in a way where Carlisle imparts his knowledge of self - control and morality to Harry. Given Carlisle's long existence as a vampire, he has a different view on life and death compared to Harry. This exchange of ideas could lead to some interesting character development for Harry. For instance, Carlisle might share stories of his past mistakes and how he overcame them, which could inspire Harry in his own battles against evil.
In some fanfictions, Harry Potter might be defiant towards Lucifer. He would use his Gryffindor courage to stand up to Lucifer's intimidation tactics. For example, when Lucifer tries to manipulate him, Harry would firmly say no and use his magic to create a protective shield.
Well, they might start off as enemies. The Stormtroopers, with their strict military discipline, could see the wizards as a threat due to their unpredictable magic. The wizards, on the other hand, might view the Stormtroopers as just another group of muggles with strange weapons.
Shifters might interact with existing characters in various ways. For example, they could be friends with Harry and help him in his battles against Voldemort. A shifter could turn into a snake to spy on the Death Eaters, providing valuable information to Harry and his friends.
They might start as antagonists. For example, if a mercenary is hired by a dark wizard to capture Harry Potter, they would directly oppose the main character. But sometimes, they can also be reluctant allies. Maybe they are offered a large sum by Dumbledore to protect Hogwarts and end up working with Harry and his friends.