Who would be the most interesting characters to pair up in a 'Ben 10 Fairy Tail crossover fanfiction'?

Lucario and Gajeel could also be an exciting pair. Gajeel is a tough and aggressive fighter, and Lucario is no slouch either. They could have some intense battles together against common enemies. Lucario's aura - sensing could help Gajeel anticipate his opponents' moves better, and Gajeel's metal - based attacks could provide a different kind of offensive power that Lucario hasn't encountered before. Their personalities, both being a bit headstrong in their own ways, could lead to some interesting character development as they learn to work together.

Another interesting pairing could be Ben and Captain America. Cap's leadership and moral compass could influence Ben, while Ben's diverse powers could be a great asset to Cap in battle. They could be in a situation where they have to fight against a mind - controlled army, and Ben's aliens like Big Chill could freeze the enemies in place while Cap gives strategic commands.

Ash and Four Arms would be a great pair. Four Arms is all about brute strength, and Ash has his knowledge of Pokemon and his own battle skills. They could work together in battles against powerful foes. Maybe Ash could learn some new fighting techniques from Four Arms, and Four Arms could learn about the subtleties of Pokemon battles. It would be a clash of two different but equally cool fighting styles.

Ben and Natsu would be an interesting pairing. Natsu is all about fire and brute strength, while Ben has the ability to transform into various aliens with different powers. They could have a friendly rivalry, like who can defeat an enemy faster. Ben could show off his alien forms to Natsu, and Natsu could teach Ben some fire - based magic tricks in return.

Ron Weasley and Four Arms from Ben 10. Ron is known for his loyalty and his skills in wizard chess. Four Arms is a strong and powerful alien. Their personalities are quite different. Ron might be a bit intimidated by Four Arms at first, but as they get to know each other, they could form an unlikely but strong team. Four Arms could help Ron in physical battles, and Ron could use his wizarding skills to protect Four Arms from magic - based attacks.

I think Harry and Natsu would be a really interesting pair. Harry is calm and calculated, often relying on his wits and the magic he has learned at Hogwarts. Natsu, on the other hand, is impulsive and powerful, using his dragon - slayer magic with great force. They would contrast each other well and could learn a lot from one another. Natsu could teach Harry about fighting with more raw power, while Harry could show Natsu the importance of strategy in a battle.

Goku and Natsu would be an interesting pair. Goku is always looking for a strong opponent to fight and improve his skills. Natsu, on the other hand, is a hot - headed but powerful wizard. Their fighting styles are quite different. Goku relies on his martial arts and ki abilities, while Natsu uses his fire dragon slayer magic. They could learn a lot from each other. For example, Goku could teach Natsu about physical conditioning, and Natsu could show Goku some unique magical techniques.

Sonic and Pikachu would be a really interesting pair. Sonic's high - speed and adventurous nature combined with Pikachu's electric powers and cute but brave personality could lead to some really fun and action - packed scenes. They could race each other and then work together to face challenges.

Naruto and Tsukune would be an interesting pair. Naruto's energetic and determined nature combined with Tsukune's kind heart and his own growth as a character in the Rosario world could lead to some great interactions. They could learn from each other's ways of dealing with challenges and protecting their friends.

Lex Luthor and Michael from Roswell would make for an exciting duo. Lex is always looking for power and knowledge, and Michael is a bit of a rebel alien. Lex might see Michael as a way to gain access to the alien technology from Roswell. Michael, on the other hand, might be suspicious of Lex but also intrigued by his resources. Their interactions would be full of tension and power plays.