Harry could be seen as a strange but powerful being. His Gryffindor courage would be respected in Asgard. Hermione might be seen as a great scholar, like the Asgardian mages. Ron could be the loyal friend who has to adapt to the grandeur of Asgard.
The Weasley twins could introduce their pranks to Asgard, causing some chaos but also some laughter. Dumbledore could be seen as an ancient and wise figure similar to Odin in some ways. Harry, with his lightning - shaped scar, might be thought to have some connection to Thor's lightning powers at first glance.
One possible plot is that Voldemort somehow has a connection to an Asgardian villain. Harry, being the hero, travels to Asgard to find a way to defeat Voldemort once and for all. Along the way, he meets the Asgardian gods. They initially doubt him but soon realize his strength. Harry then combines his wizardry with Asgardian magic to face the dual threats of Voldemort and the Asgardian foe.
A Harry Potter and Asgardian fanfiction could be really exciting. It might involve Harry Potter being magically transported to Asgard. There, he could learn about the Asgardian magic and culture. Maybe he would meet Thor and they would go on an adventure together to fight some dark force that threatens both the wizarding world and Asgard.
One interesting plot idea is when the magic systems of Asgard and Hogwarts collide. For example, the use of seiðr (Asgardian magic) in the wizarding world of Harry Potter. Another is characters from Asgard attending Hogwarts. Imagine Loki causing chaos in the halls of Hogwarts or Thor trying to fit in with the wizards.
You can start by looking on fanfiction websites like Archive of Our Own (AO3). There are often tags related to 'Asgardian' and 'Harry Potter' which can help you filter out the relevant stories. Another option is FanFiction.net, though the tagging system might be a bit different. Just search for the key terms and explore the results.
A plot could revolve around a prophecy that involves both the wizarding world and Asgard. Harry is the key figure in the prophecy. He travels to Asgard to find out more. There, he meets Odin who initially distrusts him. But as Harry proves his worth through his magical abilities and courage, Odin decides to help him. Together, they must face a common enemy that is emerging due to a dark magic that is seeping between the two worlds. Harry could also form a friendship with Sif, who teaches him some Asgardian fighting techniques.
Gwendy can fit in as a new friend to the main characters. She could join Harry, Ron and Hermione on their adventures and offer a fresh perspective. Maybe she has a different approach to solving problems, like using her knowledge of Muggle technology in a magical way.
Alucard could fit as a powerful outsider. His vampiric abilities like super strength, speed, and the ability to turn into mist or a bat would be very different from normal wizard magic. He could be a sort of anti - hero, helping Harry when it suits his own goals. For example, if there was a dark wizard using blood magic in a way that threatened Alucard's existence too.
The characters could be trainers. Harry, for example, could start his Pokemon journey in a region similar to Kanto. He might choose a Charmander as his first Pokemon, just like how he was drawn to the Firebolt in the original series. Ron could be more interested in food - related Pokemon like Snorlax. Hermione would be the type to research every single Pokemon and their abilities thoroughly before choosing her team. They could use their magic skills in a different way, like using spells to communicate with Pokemon or to enhance their Pokeballs.
They could be part of a hidden threat in the wizarding world. Maybe they were sealed away long ago and are now being accidentally released. Their presence would cause chaos as they are so different from the usual magical creatures in Harry Potter.
The Hypnosis Mic characters could fit in as new students at Hogwarts. They'd bring their modern - day style and music - based abilities. Their rap battles could be seen as a new form of magical performance in the Triwizard Tournament perhaps.