A more interesting take could be that Harry Potter and his friends accidentally travel to Asgard. There, they meet Loki and initially think he's a threat. But as they get to know him, they realize he can be an ally in their fight against Voldemort. Loki, seeing an opportunity to prove himself, decides to help them, using his unique skills in magic and trickery to outwit Voldemort's forces.
Another possibility is that the Ministry of Magic somehow discovers Loki's existence and tries to recruit him for his magical abilities. However, Loki has his own agenda and decides to use this opportunity to gain power within the wizarding world. He could form an alliance with some of the darker wizards who are looking to overthrow the Ministry, creating a whole new power struggle in the Harry Potter universe.
One idea could be that Loki, being the mischievous character he is, finds his way into the wizarding world of Harry Potter. He could start causing chaos in Hogwarts, perhaps by disguising himself as a student or a professor and playing pranks that are far more elaborate than those of the Weasley twins. For example, he might turn the entire Great Hall into an ice rink during breakfast time.
It could be a great concept. The power of a hurricane can be paralleled with the powerful magic in Harry Potter and Loki's own abilities. Maybe in the fanfiction, the hurricane is a result of a spell gone wrong that Loki has something to do with. And then Harry Potter has to figure out how to stop it while also dealing with Loki's tricks.
One idea could be a crossover where Fenrir from the Harry Potter universe somehow gets transported to the realm of Loki. Loki, being the trickster, might see Fenrir as a tool for his own schemes. Harry Potter, perhaps in a quest to stop some dark magic related to Fenrir, ends up following him and has to deal with Loki's antics as well.
One idea could be that Loki, being the mischievous character he is, finds his way into the world of Harry Potter and Supernatural. He could start causing chaos in Hogwarts by disguising himself as various characters. In the Supernatural world, he might team up with the Winchester brothers for a short time, but then double - cross them for his own amusement.
One idea could be that Tinkerbell finds her way into the wizarding world of Harry Potter. Maybe she gets accidentally transported there by some magical mishap. She could use her fairy magic in Hogwarts, like helping to repair broken objects in a more sparkly and unique way compared to the Reparo charm.
One idea could be that the Avengers are somehow transported to the wizarding world. They might be initially confused by the magic but then start to work with the Hogwarts students and teachers to fight a common enemy, like a dark wizard who has also harnessed some sort of Muggle - like technology to become even more powerful. For example, Voldemort could team up with Hydra remnants to create a super - weapon that threatens both the magical and non - magical worlds.
A fun concept could be a Transylvanian wizard coming to Hogwarts as an exchange student. This wizard has a pet dragon that is different from the ones in the UK. He brings with him knowledge of Transylvanian magic, like how to use the power of the full moon in a different way than British wizards do, which intrigues Harry and his friends.
One idea could be that the characters from Riverdale somehow find themselves in the wizarding world of Harry Potter. Maybe Jughead could be a Muggle - born wizard who discovers his powers while at Hogwarts. He might write about his strange new experiences in his journal, just like he does in Riverdale.
One idea could be that the Hulk somehow gets transported to the wizarding world. Maybe a magical experiment gone wrong by a Hogwarts student creates a portal. The Hulk's brute strength would be a shock to the wizards and witches. He could end up causing chaos in Hogwarts, knocking down walls and scaring students. Wizards would try to use spells on him, but his strength might make him resistant at first.
Another possibility is a scenario where Voldemort decides to expand his reach into the non - magical world and Batman becomes aware of this threat. He would then enter Hogwarts undercover to learn about magic and form an alliance with the Order of the Phoenix. The contrast between Batman's brooding, non - magical detective nature and the magical world would make for an interesting story.
One idea could be that Lucifer somehow ends up in the wizarding world. Maybe he's intrigued by the magic there and decides to play some tricks on the Hogwarts students. He could start by disguising himself as a new dark arts teacher, causing chaos in the classrooms.