I think Kakashi and Gray would have some cool interactions. Gray's ice - magic and Kakashi's fire - based attacks (like Fireball Jutsu) could lead to some interesting battles or training sessions. Also, Kakashi and Lucy could be fun. Lucy's celestial spirit magic and Kakashi's summoning jutsu could be compared and contrasted. And of course, Kakashi and Makarov. The old and wise guild master could give Kakashi some unique insights about the Fairy Tail world, and Kakashi could share his ninja wisdom with Makarov.
Another interesting interaction would be between Deadpool and Gray. Gray is cool - headed (pun intended) and has his own unique fighting style with ice - make magic. Deadpool's chaotic fighting style would contrast greatly with Gray's. They could start off as rivals, with Deadpool constantly taunting Gray about his stripping habit, but then as they face a common enemy, they would have to learn to work together. This would lead to some great character development and some hilarious exchanges as Deadpool tries to understand Gray's magic and Gray tries to tolerate Deadpool's antics.
Itachi and Gray could also have great interactions. Gray is a cool - headed ice mage. When he meets Itachi, they could compare their elemental powers (Itachi's fire - based jutsu and Gray's ice magic). They might also bond over their somewhat stoic personalities and the secrets they both carry.
Definitely Haru and Natsu. They are both hot - headed and full of energy. Their interactions would be really explosive. Haru with his Rave power and Natsu with his Fire Dragon Slayer magic would probably start off by competing with each other in terms of strength, but then realize they need to work together. Another interesting interaction could be between Elie from Rave Master and Lucy from Fairy Tail. They are both strong female characters with different kinds of magic, and they could share their experiences and knowledge about magic.
Imagine Luffy (since he has the Quake - Quake Fruit in this fanfiction idea) interacting with Gray from Fairy Tail. Luffy's carefree and bold nature against Gray's cool and sometimes brooding personality. Luffy could show off the power of the fruit, and Gray might try to freeze the seismic waves. It would be a clash of different powers and personalities. Also, Hinata from Naruto and Lucy from Fairy Tail could have a sweet interaction. Hinata could be shy around Lucy at first, but they could bond over their support for their respective teams.
Definitely Kakashi and Percy. They are both protagonists in their own right, and seeing how their different personalities interact would be fascinating. Percy is impulsive and has a strong sense of justice, while Kakashi is more reserved and calculating.
Definitely Gray. Their personalities are quite different. Gray is cool - headed and uses ice magic, while Wolverine is more of a rough - and - tumble fighter. The contrast in their powers and attitudes would lead to some great banter and interesting team - up moments.
Yugi and Natsu would be an interesting pairing. Yugi is calm and strategic, while Natsu is impulsive and powerful. They could balance each other out. Yugi could use his intelligence to plan their adventures, while Natsu could use his fire - based magic to fight off enemies. Another interesting pair could be Erza and Kaiba. Erza is a strong and disciplined warrior, and Kaiba is a proud and powerful Duelist. They could have some epic battles of wills and skills.
Erza and Captain America would be an amazing combination. Erza is a strong and disciplined warrior in Fairy Tail, and Captain America is the symbol of justice and leadership in the Avengers. Erza's various armors and combat skills combined with Captain America's shield and strategic thinking would make them a formidable team. They could lead the combined forces of Fairy Tail and the Avengers in battles against powerful foes, and also inspire the other characters with their unwavering determination.
Spiderman and Erza would make for a strong pairing. Erza is a very powerful and disciplined mage. Spiderman could be in awe of her combat skills and leadership. They could fight side - side against powerful enemies, with Spiderman using his webs and agility and Erza with her various armors and weapons.
Erza and Byakuya would be an interesting pair. Erza's leadership and unwavering determination in Fairy Tail, and Byakuya's noble and stoic nature in Bleach. They might initially have a bit of a standoff due to their pride, but as they face challenges together, they would come to understand each other's values and form a mutual respect.