Well, his role could be that of a mentor. Zoro has a lot of combat experience. He could teach the younger members of Fairy Tail some new fighting techniques. He might also be a bit of an outsider at first, not really understanding all the magic stuff, but then he'd gradually adapt and start to incorporate magic - like sword - based magic perhaps - into his fighting style.
Zoro's serious and determined personality would contrast with some of the more laid - back members of Fairy Tail. But it could also be a good influence. He would keep everyone focused during tough times.
If Kakashi were to join Fairy Tail, it would be an interesting mix. Kakashi is a highly skilled ninja from the Naruto universe, known for his Sharingan and diverse jutsu. In Fairy Tail, he'd likely bring in a whole new set of combat techniques. His calm and collected demeanor would contrast with some of the more boisterous members of Fairy Tail. He might also form interesting relationships. For example, he could bond with Erza over their shared combat experience and sense of justice. And his intelligence could be used to help plan strategies for the guild's battles.
Well, in such a fanfiction, Gajeel would bring a whole new energy. He might be more rebellious as a youngster. His journey to find his place in Fairy Tail could involve getting into small scuffles with other members at first. But as time passes, he realizes that Fairy Tail is a place where he can belong. His growth could be shown through his changing attitude towards the guild's rules and values.
One aspect that could be explored in this fanfiction is Gajeel's growth in magic. As a kid joining Fairy Tail, he would be exposed to different types of magic and training methods. Maybe he starts off with his Iron Dragon Slayer magic being quite basic, and then with the help of the guild's masters and other members, he refines it. He could also learn new skills that complement his existing magic, which would not only make him stronger but also show his development within the guild.
If Naruto joined Fairy Tail, it would be really interesting. He has a lot of chakra which could be something new in the world of Fairy Tail. He might get into some friendly rivalries with the strong mages there. Also, his ability to make friends easily would help him bond with the Fairy Tail guild members quickly. And his dream of becoming Hokage could translate into a new big dream within the Fairy Tail context, like becoming the strongest mage or something.
One interesting Zoro Fairy Tail fanfiction could be one where Zoro from 'One Piece' somehow ends up in the world of 'Fairy Tail' and has to adapt to their magic system. He might start challenging the wizards there to sword fights, which would be really cool to read.
You can try fanfiction websites like Archive of Our Own (AO3). It has a large collection of fanfictions from various fandoms, including crossovers like Zoro from 'One Piece' and 'Fairy Tail'. The search function there is quite good, allowing you to filter by tags such as 'Zoro', 'Fairy Tail', and 'crossover' to find relevant stories.
Naruto's personality is a key factor. His determination is unbreakable. In Fairy Tail, this would mean he'd never back down from a challenge, no matter how tough. His ability to forgive and see the good in people would be a great influence. For example, if there were members who had a dark past or made mistakes, Naruto would be the one to accept them and encourage them to move forward. His sense of humor, though sometimes a bit silly, would lighten the mood during difficult times in the guild. All in all, his personality would have a very positive impact on Fairy Tail.
Ichigo in Fairy Tail? It would be amazing. He could help the guild in battles against powerful dark guilds. His Hollow - like powers might be seen as something very strange and dangerous by some in the guild, but once they understand him, they would accept him. His relationship with the guild master would also be interesting. He might not be used to the rowdy and fun - loving nature of Fairy Tail at first, but over time, he would become an integral part of the guild.