Hermione would be a great character to focus on. She is intelligent and curious. In a fanfiction involving the Heartless from Kingdom Hearts, she would be the one who would immediately start researching about them. She would try to find any connections between the magic in the Harry Potter world and the existence of the Heartless. Her thirst for knowledge would lead her to make some interesting discoveries and she could potentially come up with unique ways to combat the Heartless using magic spells and potions.
Sora from Kingdom Hearts in the context of the Harry Potter world would be really interesting. Imagine Sora arriving in Hogwarts. He has his Keyblade and his experience with fighting the Heartless. He would be like a fish out of water in the wizarding world. The wizards would be both fascinated and a bit wary of him. He could teach the Harry Potter characters some of his combat moves against the Heartless and in return, learn about magic from them. His positive and determined attitude would contrast with the often more solemn and serious atmosphere in Hogwarts.
I think Harry himself would be the most interesting. He has already faced so many dark forces in his own world. When the Heartless show up, he would be the one who would feel a sense of responsibility to protect his friends and Hogwarts. He has the courage and the ability to adapt. He could form an interesting bond with characters from Kingdom Hearts. His experiences with the Dementors could give him some insight into dealing with the Heartless, as both seem to feed on something negative (souls/ hearts). And he would be the one to lead the fight against any new threat that the Heartless bring to the wizarding world.
I think pairing Harry Potter with Sora would be really interesting. Harry has his own set of magical abilities and a strong sense of justice, while Sora has the power of the Keyblade and a lot of heart. They could learn a great deal from each other. Harry could show Sora some of the more complex spells in the wizarding world, and Sora could introduce Harry to the concept of different worlds and the power of the heart.
Sora would be a great choice. He's already a central character in the Kingdom Hearts series. In a Keyblade Wars fanfiction, seeing how he adapts to the chaos of the war, his moral compass in the face of such a large - scale conflict, and how his relationships with other Keyblade wielders change would be really interesting.
Sora would be really interesting. His naivete and pure heart could be a great contrast to the dark and gritty world of Blade. He would probably approach the vampire - fighting situation with his usual optimism and might even try to find a way to redeem some of the vampires, thinking they are like the lost souls he has saved in the Kingdom Hearts worlds.
Naruto would be very interesting. His boisterous personality and his strong sense of justice would make for great interactions in the Kingdom Hearts universe. He could be constantly amazed by the different worlds and the magic in the Kingdom Hearts setting, and his growth as a character could be explored further as he faces new challenges outside of his own world.
Sora would be really interesting. He has such an innocent and determined nature in 'Kingdom Hearts'. In the 'Once Upon a Time' setting, he could be the one to bring a sense of hope and adventure. His reactions to the different fairy - tale characters and settings would be fun to explore.
One possible plot could be that the Heartless somehow find their way into the wizarding world of Harry Potter. Harry and his friends initially mistake them for some new dark magic creatures. As they investigate, they discover that the Heartless are connected to a strange new threat that is draining the magic essence from the wizarding world, similar to how they seek hearts in Kingdom Hearts. Harry then has to use his knowledge of magic and work with some characters who might have knowledge of the Heartless from the Kingdom Hearts universe to stop this new evil.
I think Lincoln would be the most interesting. He's used to handling a big family and all kinds of chaos at home. In the Kingdom Hearts universe, he could use his adaptability and problem - solving skills. He'd be curious about the new worlds and the magic there, and his journey of discovery would be really engaging to read about as he teams up with Kingdom Hearts characters.
Definitely Harry himself. His ability to adapt to new situations and his powerful magic would be really interesting in the Kingdom Hearts setting. Also, Sora. The clash or cooperation between Harry's magic and Sora's Keyblade skills would be cool to see. And Hermione, she could bring her intelligence and knowledge to analyze the new world they are in.
Doctor Strange would be an interesting character to focus on in a Harry Potter MCU fanfiction. He already has knowledge of magic in the MCU, but it's a different kind of magic compared to that in Harry Potter. He could compare and contrast the two magics, and perhaps even learn new spells from the Harry Potter universe. His presence could also bridge the gap between the two universes in terms of magic.
Sora and Harry Potter would be a really interesting pair. Sora is this optimistic and brave Keyblade wielder, and Harry is the Boy Who Lived. They could learn a lot from each other. Sora could show Harry about the different worlds he has visited, and Harry could introduce Sora to the magical world of Hogwarts. They could also share their experiences of facing great evil and finding the strength within themselves to keep going.