It really depends on the situation. If it's in a magical environment like Hogwarts, Harry might have an advantage with all the spells he knows. But if it's an open area, Ben with his Omnitrix could transform into an alien like Way Big and overpower Harry with his size and strength.
One great 'Ben 10' and 'Harry Potter' fanfiction is 'Ben Potter'. In this story, Ben Tennyson somehow finds himself in the wizarding world of Harry Potter. He has to deal with the magical threats there using his Omnitrix. It's a really interesting crossover as it combines the high - tech alien - transforming device from 'Ben 10' with the magic of 'Harry Potter'.
There's a fanfiction where the Hogwarts houses are reimagined as different species from 'Ben 10'. So, Gryffindor might be like the Pyronites (the fire - based aliens in 'Ben 10'), known for their courage. Slytherin could be related to the Ectonurites (the ghost - like aliens), representing their sly nature. This reimagining creates a whole new dynamic within the Hogwarts world and also allows for some interesting interactions between the 'Ben 10' and 'Harry Potter' elements.
One interesting crossover could be Ben using his alien forms to help the students at Hogwarts during a dark wizard attack. For example, his Heatblast form could be useful against ice spells. Another could be Harry Potter using magic to enhance Ben's Omnitrix. Maybe a spell that makes it transform faster or unlock new alien forms.
A common crossover concept is the idea of Ben attending Hogwarts. He would bring his street - smart attitude and his alien - fighting skills. His presence could disrupt the normal hierarchy at Hogwarts. He might get into trouble for using his alien powers instead of magic for certain tasks, but also prove to be a great asset when it comes to facing dark wizards. And his friends from the Ben 10 universe could potentially visit Hogwarts too, causing all sorts of chaos and adventure.
Well, it depends on how it's executed. If the writer is able to blend the unique characteristics of Harry Potter, such as the wizarding world with its spells and Hogwarts, and the aspects of Ben Kojou's story in a seamless way, it can be really engaging. However, if not done properly, it could seem like a jumbled mess. For example, if the rules of magic from both worlds clash without proper explanation, it might be off - putting to readers.
Well, perhaps there's a magical artifact in the Harry Potter world that is malfunctioning and causing strange rifts in the universe. Ben 10 stumbles upon one of these rifts and ends up in Hogwarts. He teams up with Harry Potter and his friends. Ben realizes that his alien forms have different reactions to magic. Heatblast, for instance, can withstand some of the dark magic spells better than his human form, and together they embark on a journey to fix the artifact and close the rifts.
One great 'Ben Oc Harry Potter fanfiction' is 'The Lost Heir of Slytherin'. It has an interesting plot where the OC, Ben, discovers his hidden connection to Slytherin and has to navigate the politics and secrets within Hogwarts. Another one could be 'Ben's Magical Adventures' which focuses on Ben's unique magical abilities that are different from the normal Hogwarts curriculum.
The characterizations would be a big issue. Harry Potter characters have their own well - established personalities and powers, and the same goes for Ben Kojou characters. Keeping them true to their original selves while also making them fit into this new fanfiction scenario is not easy. For instance, Harry's sense of justice and Hermione's intelligence need to be maintained, and at the same time, they have to interact with Ben Kojou's characters without losing their essence.
The combination of Ben Solo from Star Wars and the world of Harry Potter in slash fanfiction is unique because it blends two very different universes. It allows for interesting character interactions that you wouldn't normally see, like how Ben Solo's powers and personality might interact with the magic and characters of Harry Potter.