Well, Gaara's sand - based powers could be really unique in the Fairy Tail universe. His ability to control sand could be seen as a new type of magic. Maybe he could use it in combination with Fairy Tail's team - based combat. For example, he could create sand barriers to protect his teammates during battles, just like he did in his own world to protect his village.
In a Fairy Tail fanfiction, Gaara could experience a change in his view of family. Fairy Tail is like a big family. Gaara, who had a troubled relationship with his own family in his world, could find a new kind of family here. He could start to trust and care for his guildmates as if they were his own family. This would be a huge step in his character development as he learns about love, loyalty, and the importance of having people who truly care about you in your life. It would also make him more confident in himself and his place in the world, as he now has a support system that he never had before.
His powers would also develop in new ways. He could learn to combine his sand powers with Fairy Tail magic. For example, he might learn how to use fire magic to heat up his sand and make it more powerful in attacks. Emotionally, seeing the love and loyalty in Fairy Tail could make him less cold and distant. He may start to value friendship more and his past traumas might start to heal as he is surrounded by such a positive and accepting group.
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.
Another concept could be that characters from Fairy Tail visit the Naruto world. Natsu, for example, might be intrigued by Gaara's control over sand, which is somewhat similar to his own fire - based magic in terms of its unique nature. And they could all participate in the Chunin Exams together, which would be a chaotic and exciting event.
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.
One interesting story could be where Gaara, with his sand powers, joins Fairy Tail and has to learn to work with the guild's mages. He might initially struggle to fit in due to his reserved nature, but then forms strong bonds with some of the characters like Natsu, who helps him open up. Another could be a story where Gaara's past traumas are explored in the context of the Fairy Tail world, and the guild members help him heal. There could also be a fanfiction where Gaara uses his unique abilities to help Fairy Tail in a big battle against a powerful dark guild.