One idea could be a wizard discovers Beyblades in the Muggle world and decides to bring them to Hogwarts. He then challenges his classmates to Beyblade battles instead of duels. The different houses could form their own Beyblade teams and compete in a tournament, with the winning house getting extra house points and a special magical Beyblade as a prize.
A new student arrives at Hogwarts who is a master at Beyblading. He comes from a family that has a long history of both magic and Beyblading. He challenges the most popular students at Hogwarts to a Beyblade battle. If he wins, he wants to change some of the old - fashioned rules at the school. Harry and his friends are caught in the middle, not sure whether to support the new kid or the status quo.
Maybe there's a hidden chamber in Hogwarts that contains ancient Beyblades with magical powers. Harry and his friends accidentally stumble upon it. They soon find out that these Beyblades can be used to fight against dark forces that are starting to seep into the school. They have to learn how to control the Beyblades and use their magic to enhance their performance in battles.
One idea could be that during a Quidditch match, a player gets seriously injured. Instead of using magic to heal right away, an ambulance from the Muggle world is called in by a confused bystander. The ambulance crew has to deal with the magical aspects they've never seen before while trying to transport the patient to a Muggle hospital. This could lead to a lot of comical and also tense situations as they try to figure out how to handle the situation.
One possibility could be that Supergirl somehow ends up in the wizarding world of Harry Potter. Maybe she's chasing a powerful magical artifact that has fallen into the wrong hands in Hogwarts. She could use her superpowers to help Harry and his friends during a particularly tough battle against Voldemort, like using her heat vision to fend off Dementors or her super strength to break through some dark magic barriers.
One idea could be Harry using parkour skills to escape from the Death Eaters in the Forbidden Forest. He jumps from tree to tree, slides under fallen logs, and uses his magical abilities in combination with his newfound parkour skills to outmaneuver them.
One idea could be that Voldemort discovers the power of the Stargate and tries to use it to gain more power. He could send his Death Eaters through the Stargate to conquer other worlds and bring back resources or powerful artifacts to help him in his quest to take over the wizarding world. The Order of the Phoenix would then have to follow through the Stargate to stop him.
One idea could be that the Justice League somehow ends up in the wizarding world. Maybe a magical portal opens during a battle in their universe and sucks them into Hogwarts. Superman's powers could be affected by the magic there, and Batman would be intrigued by the complex magic system and start studying it. Harry Potter and his friends could team up with the Justice League to fight a new dark force that threatens both the magical and non - magical worlds.
In this fanfic, the plot could center around Harry's identity crisis. He's adopted by wolves, so he has this wild, untamed side, but he also has his wizarding roots. He might struggle to fit in when he finally enters the wizarding world. The wolves could have taught him a different moral code, and he has to reconcile that with the rules and values of Hogwarts. This internal conflict could drive the story forward, with him making new friends who either accept or reject his wolf - like qualities.
Well, a plot could involve a magical artifact in the Diablo universe that has the power to influence the balance of magic in the Harry Potter world. Malthael, being associated with such powerful and otherworldly forces, is sent to retrieve it. Harry Potter and his friends discover this and think Malthael is up to no good. So they engage in a sort of cat - and - mouse chase. Along the way, they start to learn about each other's worlds. For example, Malthael could teach them about the different forms of death in his world, while Harry could show Malthael the power of love and friendship in his universe, which might change Malthael's perspective on things.
Perhaps in the crossover, the Prototype virus could somehow infect the magical creatures in the Harry Potter universe. This would lead to a crisis where normal spells and magic can't stop the infected creatures. Harry and his friends would have to seek help from Mercer, who understands the virus. Together, they could try to find a way to either cure the infected or contain the spread. Mercer might use his own knowledge of the virus and his powers to fight the infected creatures, while Harry uses his magic skills to protect Mercer from magical attacks.
Well, perhaps there's a magical portal that connects the Ghostbusters' New York City to Hogwarts. And some mischievous Hogwarts ghosts accidentally pass through it and start causing chaos in NYC. The Ghostbusters, not knowing anything about magic at first, have to team up with Harry Potter and his friends who come to NYC through the portal to figure out how to send the ghosts back. They learn from each other's worlds in the process.
A story could be centered around a tournament in the combined world of Harry Potter and Kantai Collection. Wizards and shipgirls compete in various challenges. For example, the shipgirls might have to navigate through a magically - created maze, while the wizards have to use their magic to repair damaged ships. Harry and his friends would be in teams with some of the shipgirls, and they have to learn to work together to win the tournament.