Goku would likely interact with Natsu in an interesting way. They both love to fight and are always looking for a strong opponent. They might start off as rivals and then become friends. Goku would also probably be friendly with Lucy, being intrigued by her celestial spirit magic.
The interactions could be really interesting. Goku's straightforward and somewhat naive personality in the face of new things would contrast with the more complex relationships and personalities in Fairy Tail. For instance, when he meets Mirajane, she would probably be very kind to him, offering him food and a place to stay at the guild. Goku would then repay her kindness by helping out with any threats that come the guild's way. And with Happy, Goku would find his flying ability really cool and might even try to learn how to fly in the same way, which would be a comical scene.
If DBZ Goku were in Fairy Tail, his sense of justice would fit right in. He could form strong bonds with the Fairy Tail members. His training regime might even influence some of the wizards to train harder. And when it comes to battles, his ability to sense energy would give him an edge over many foes. He could also learn some of the Fairy Tail magic techniques and combine them with his own powers in really interesting ways.
Goku's ki - based powers could be seen as a parallel to the magic in Fairy Tail. His attacks like the Dragon Fist could be considered similar to some of the dragon - slayer magic in the series. When he uses his ki blasts, the mages in Fairy Tail might initially mistake it for a very powerful and unknown type of magic. Goku could also learn to sense ki in a way that helps him detect magic users and their power levels more easily.
The characters would likely start off being cautious of each other. For instance, the devils in Highschool DxD might be wary of the mages from Fairy Tail as they have different power sources. However, as they get to know each other, they could start to learn from one another. Gray could teach some of the Highschool DxD characters about his ice - making skills, while Issei could show the Fairy Tail members some of his unique devil techniques.
The Fairy Tail characters are used to a world full of magic and guilds. When they enter the Highschool DxD world, they would bring their sense of camaraderie and loyalty. Characters like Erza would immediately assess the situation and try to find a way to protect her friends. In the DxD world, she might find some kindred spirits in the more honorable devils. Meanwhile, the Highschool DxD characters are used to a world of different species and complex power dynamics. They would be curious about the Fairy Tail magic. For instance, the magic items used in Fairy Tail could be very appealing to some of the DxD characters. There could be a lot of cultural exchange and some tense moments as they figure out how to co - exist and whether they can trust each other.
Well, if we think about it, Thor is a very proud and strong warrior. He might initially look down on some of the younger Fairy Tail members, thinking they are weak. But when he sees their determination and the unique magic they possess, he'd start to respect them. For instance, when he sees Lucy summon her celestial spirits, he'd be intrigued as it's a different form of power compared to his.
For Ruby, the concept of Fairy Tail's magic guilds could be really appealing. She might imagine herself being part of one. Yang would find the idea of the S - Class mages interesting and might want to prove herself against them. Weiss would analyze how the Fairy Tail world manages its economy with all the magic and quests. Blake would be interested in the relationships between the different guilds and how they cooperate or compete. All in all, each RWBY character would interact with the Fairy Tail concepts in different ways based on their own traits and goals.
For Zabuza from 'Naruto' in a 'Fairy Tail' fanfiction, he would interact with the characters in a very direct and often violent way. He would see the Fairy Tail mages as targets or obstacles. If he was hired to kill someone in the guild, he would not hesitate to use his sword skills against them. He might not understand the concept of friendship and loyalty that is so strong in the Fairy Tail guild and this could lead to some interesting clashes.
The characters from Fairy Tail might see the Pokemon as strange but interesting creatures. They could try to befriend them and use their powers together. For example, Natsu might befriend a Charizard and they could team up in battles.
The Fairy Tail guild as a whole could work together. They could use their combined magic to create a powerful spell. For example, they could combine the elements of fire, ice, wind, etc. to create a spell that might be able to hold Deathwing back or even send him back to his own realm. They would need to communicate and coordinate well, which would be a challenge given the different personalities in the guild.