I think it would be really interesting to focus on Kakashi in this fanfiction. He's a very intelligent and experienced character. In the Kingdom Hearts universe, he could use his Sharingan to analyze the Heartless and other strange phenomena. His laid - back yet serious attitude would create some really cool moments when interacting with characters from Kingdom Hearts, and his strategic mind could be crucial in battles against the new threats in this crossover universe.
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.
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.
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 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.
Ruby and Sora would be a really interesting pairing. Ruby is young and full of energy, always eager to help and fight for what's right. Sora is the same, with his big heart and determination. They could learn a lot from each other, like Ruby could show Sora some of her cool scythe techniques and Sora could teach Ruby more about using the Keyblade effectively.
Aqua and Ignis could also be an interesting pair. Aqua's strong magical abilities and discipline as a Keyblade Master could be compared and combined with Ignis' strategic mind and combat skills. They might work together to solve complex problems that require both magic and strategy.
Another interesting pairing could be Sakura and Kairi. Sakura is a strong - willed kunoichi who has grown from being a bit of a fangirl to a capable fighter. Kairi is also a strong - hearted girl. They could bond over their experiences of being in the background sometimes but still being important to their respective groups. They might even learn some new self - defense moves from each other.
I think the interaction between Sora and Crono would be really interesting. Sora is this optimistic Keyblade wielder, always looking for his friends and fighting for the light. Crono, on the other hand, is a time - traveling hero. They could share their experiences about different worlds and how to fight against evil. Sora could learn about time travel from Crono, and Crono could learn about the power of the heart from Sora.
Riku and Alleyne would make a great pair. Riku has his complex past and his strong will. Alleyne is a skilled fighter. They could have some really intense battles side by side and also have deep conversations about their respective worlds and their goals. Riku might be able to teach Alleyne some new ways of using her sword, and she could show him different combat strategies from the Queens Blade world.
Ainz Ooal Gown would be very interesting. His complex personality, with his mix of pride as an Overlord and his insecurities hidden beneath, would create a lot of depth. In the Naruto world, his reactions to the different values and cultures would be fascinating. For example, how would he deal with the concept of chakra compared to his own magic? And how would he interact with the ninjas who have such different combat styles and moral codes from his undead minions?
Sora and Spider - Man would be a really cool pairing. Sora has his acrobatic skills with the Keyblade, and Spider - Man is all about agility and using his webs in combat. They could have a great time swapping stories about their different worlds and learning new moves from each other. For instance, Sora could teach Spider - Man some basic Keyblade forms, and Spider - Man could show Sora how to use his environment better for combat, like swinging from buildings.