Well, Harry Potter characters like Harry himself might be initially distrustful of Loki due to his reputation for trickery. However, Loki could use his charm to win them over eventually. In the case of the Supernatural characters, Dean and Sam Winchester would likely be on high alert around Loki. They might try to keep him in check while also being curious about his powers. Harry Potter characters could offer their magical knowledge to the Winchesters, and the Winchesters could share their combat and survival skills with the Hogwarts students.
In a fanfiction, the interaction could start with a magical accident that brings the characters together. Loki, being the wildcard, would immediately start testing the boundaries of this new situation. The Harry Potter characters would be in awe of the Supernatural world's different kind of magic and the way the Winchesters handle it. The Winchesters, on the other hand, would be a bit skeptical of the Hogwarts magic at first. Loki could play both sides, sometimes helping the Harry Potter characters understand the Supernatural world and other times causing small troubles between the two groups. Eventually, they would have to learn to work together, with Loki using his wits, the Harry Potter characters their spells, and the Winchesters their hunting expertise to face whatever challenges come their way.
Harry Potter would likely be very cautious around Loki. Given Loki's reputation for trickery, Harry would be on his guard. When it comes to the giant snake, if Loki was controlling it, Harry might try to reason with Loki first, knowing that a direct confrontation with the snake could be dangerous. He would use his knowledge of magic and the values of the wizarding world to try and persuade Loki to stop whatever he was planning. Loki, on the other hand, would probably be amused by Harry's earnestness and might play with him a bit before revealing his true intentions regarding the snake.
He would probably interact with Hermione in an interesting way. Hermione, being a stickler for the rules, might be both impressed and a bit frustrated with Harry's Loki - like ways of bending the law. He could use his charm to convince her that his unorthodox methods are necessary to achieve justice.
Well, Gabriel could be a key figure in helping Harry Potter understand some of the deeper mysteries of magic. Since Gabriel has a different kind of power in the Supernatural world, he could show Harry that there are other ways to use magic that are not taught at Hogwarts. For instance, he could teach Harry how to use magic to manipulate time on a small scale, which could be useful in Harry's fight against the Dark Arts. And Harry, in turn, could introduce Gabriel to the rich magical culture and history of the wizarding world, like the story of the four founders of Hogwarts or the origin of the Hallows.
Harry Potter would likely be in awe of Hercules' strength at first. He might be a bit cautious too, as Hercules is from a different world of gods and myths. But they would probably quickly become friends as they both have a strong sense of justice. Hermione would be very interested in Hercules' stories about the Greek gods and would constantly ask him questions, trying to learn as much as she could.
Loki is used to being in a world of power plays and politics in Asgard. Fem Harry Potter, coming from the more straightforward (although not without its own intrigues) wizarding world, would bring a fresh perspective. Their personalities would clash at times, but also complement each other. Harry's loyalty to her friends and her belief in the power of love could rub off on Loki, while Loki's adaptability and his knowledge of different magics could enhance Harry's abilities.
Harry would probably be cautious at first. He's used to the magic in his world, and an Imperial Arm would be something new. He might study it carefully, like he does with new spells. Hermione would be all about researching it, looking for any information she could find. Ron might be a bit more skeptical, but still curious. They would all approach it with the mindset of trying to understand how it fits into their world of magic.
Moana would likely be curious about the magic in Harry Potter's world. She might ask Harry to show her some spells, like the levitation charm. Harry, on the other hand, would be impressed by Moana's courage and her ability to sail across the ocean. He could learn from her about determination. Hermione might study the culture of Moana's island, and Moana could learn about Hermione's love for books and knowledge.
The characters would have very different worldviews. For example, the wizards in Harry Potter are used to a world where magic solves many problems. But the Firefly crew has to rely on their wits, technology and sometimes brute force. So there could be initial misunderstandings. Harry might try to use magic to fix a broken part on the Firefly ship, but Mal might not trust this strange 'power' at first.
Dumbledore would be a wise figure for Eragon to meet. Dumbledore could offer insights into different types of magic and how to use them for good. Eragon would respect Dumbledore's knowledge and power. In return, Eragon could share with Dumbledore the ways of his own magic, which is more nature - based. Voldemort, if he were still around in this crossover, would see Eragon as a threat because of his unique magic and his dragon. Eragon would not tolerate Voldemort's evil ways and would be ready to fight him alongside Harry and his friends.
In a crossover, characters would interact in interesting ways. For instance, the magic in Harry Potter is more about spells and potions, while Rapunzel's magic is in her hair. When they meet, characters like Hagrid from Harry Potter might be really interested in Rapunzel's hair as it is a very unique form of magic. Rapunzel could learn about the different magical creatures in Harry Potter's world from Hagrid. Meanwhile, the villains would also interact. Mother Gothel could potentially team up with some of the dark wizards from Harry Potter. However, the heroes like Harry, Hermione, Rapunzel and Flynn would have to put aside their differences in magic and upbringing to fight against this combined evil. They would learn from each other's strengths, for example, Rapunzel's kindness and ability to see the good in people could influence Harry, and Harry's determination in the face of great evil could inspire Rapunzel.