The characters would likely have a mix of confusion and fascination. For instance, Harry Potter might be intrigued by the unique powers of the devils in High School DxD like Issei's Boosted Gear. On the other hand, the devils in DxD could be in awe of the complex magic system in the Harry Potter world. They would have to communicate and find common ground to work together, which could lead to some interesting cultural exchanges.
In a fanfiction, the characters could interact through a shared goal. Let's say there is a threat that endangers both worlds. Hermione from Harry Potter would use her vast knowledge of magic to come up with strategies. She would collaborate with the intelligent characters in DxD like Akeno. They would share ideas and combine their different forms of power. Harry and his friends would also learn about loyalty and friendship in a different way from the relationships in DxD, which could strengthen their own bonds.
Some characters might be initially hostile. Consider Draco Malfoy from Harry Potter encountering the devils in DxD. He might be judgmental and see them as 'dark creatures' similar to how he views werewolves and half - bloods in his own world. However, through various events, he could come to understand that they are not all bad. Meanwhile, Rias from DxD might find the Hogwarts students a bit naive in terms of combat compared to her own experience, but also recognize their value in terms of magic knowledge.
Well, Ben could use his alien forms to help out the characters in High School DxD in battles. For example, if there's a fight against a powerful devil, Ben could transform into Four Arms and use his super strength. The characters in DxD would be amazed by his abilities.
The Power Rangers, being used to a more action - oriented and team - based dynamic, would likely bring their sense of discipline and cooperation to the interactions. They might be initially confused by the more chaotic and hormonal nature of the High School DxD characters. The High School DxD characters, on the other hand, would be intrigued by the Rangers' powers and technology. Issei, for example, might be eager to learn about the Rangers' combat skills and see if he could incorporate them into his own fighting style.
Ash would probably be curious about the devils and angels in High School DxD. He might try to befriend them with his friendly and innocent nature. The devils and angels, on the other hand, would be intrigued by Ash's Pokemon.
Yes, there are likely some crossover fanfics out there. Writers often like to combine different popular universes to create unique stories. In such a crossover, you might see characters from Harry Potter interacting with those from High School DxD in all sorts of interesting ways, like Hogwarts students using magic in the world of High School DxD or the devils in High School DxD being introduced to the wizarding world.
He might also interact with Rias. Rias is a powerful devil and a leader. Sans could approach her with his laid - back attitude. She might be initially suspicious of him but later come to respect his abilities. They could have some strategic discussions about dealing with common enemies in the High School DxD world. And Sans could probably crack some jokes that would either amuse or baffle Rias.
Pit from Kid Icarus is very innocent and pure - hearted. He would be quite shocked by the more lust - driven characters in High School DxD like Issei at first. But over time, his positive attitude might influence Issei to be a bit more noble in his pursuits.
One possible plot could be a crossover where the magic from Harry Potter world somehow seeps into the High School DxD universe. For example, the Hogwarts students end up in the DxD world and have to adapt to the different rules regarding devils, angels and fallen angels. They could use their magic to help or hinder the various factions in DxD depending on their motives.
One possible plotline could be that a character from Harry Potter accidentally ends up in the world of High School DxD. For example, Ron could be transported there and have to figure out how to get back while dealing with the devils and angels in that world.
There are many potential characters. The teachers at Forks High School for sure. Harry could have interesting conversations with them. Also, if there are any other supernatural beings in the Forks universe in this fanfiction, like werewolves, he could interact with them. And of course, the students who are into different clubs and activities at the school. He might bond with the science - loving students or those on the school newspaper team, sharing his own experiences from Hogwarts in a veiled way.
Naruto characters could be in awe of the devils and angels in the High School DxD world. When it comes to Great Red, Naruto himself might see it as a new and powerful force to either befriend or fight. He could try to use his Rasengan or other jutsu against it if it poses a threat.