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.
Well, a common plotline is Gajeel's redemption arc. He has to prove that he's changed from his bad - boy ways in Phantom Lord. Some fanfictions focus on how he overcomes the prejudice from certain Fairy Tail members. There are also those that delve into his backstory more deeply, like his relationship with Metalicana, his dragon father. And of course, his role in big guild - wide events like the Grand Magic Games, where he showcases his strength and loyalty to Fairy Tail.
His character develops through forming bonds. With Levy, he learns to be more open and less gruff. He also becomes more of a team player within Fairy Tail. He starts to care about the guild's reputation and the well - being of its members.
Perhaps a fanfiction where Gajeel is cursed with a blue mark that slowly drains his energy. Levy, being the studious mage she is, devotes all her time to finding a cure. Along the way, they have to face many enemies who are after Gajeel's power. Their love and friendship are put to the test as they struggle to break the curse.
A lemon fanfic about Gajeel and Levy in Fairy Tail often explores their relationship in a more romantic or spicy way. It might include their growing feelings for each other, with some added elements of passion. However, it's important to note that such fanfics are not part of the official canon.
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.
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.
Often, their relationship is one of legacy. Metalicana's power and influence are seen in Gajeel. Fanfictions might show how Gajeel uses Metalicana's techniques in battles. And when Gajeel faces tough situations, he remembers Metalicana's words of wisdom. It's like Metalicana is always with him in spirit, guiding him through his adventures in Fairy Tail.