The plot could start with Naruto and Itachi being lost in a strange dimension which turns out to be the world of Fairy Tail. At first, the Fairy Tail members are cautious around them. But as they see Naruto's loyalty and Itachi's strength used for good, they are welcomed. They could participate in the Grand Magic Games. Naruto would be excited to show off his skills and Itachi would be more reserved but still very effective. Their presence would change the power dynamics in the guild and lead to new adventures against powerful foes.
Well, a great plot twist could be that Akatsuki is actually being controlled by a greater evil force that neither Naruto nor Itachi knew about. When they join, they start to notice strange behavior among the members that doesn't seem to align with the original goals of Akatsuki. Naruto, with his unwavering belief in friendship and Itachi's strategic mind, might then team up to expose this greater threat and save the ninja world. It would also be interesting if their joining Akatsuki causes a rift among the members, some seeing them as potential allies and others as enemies.
One idea could be that Sting and Rogue initially come to Fairy Tail as spies for Sabertooth, but as they interact with the Fairy Tail members, they start to question their loyalty to their old guild. They could be paired up with different Fairy Tail mages on missions. For example, Sting with Natsu and Rogue with Gray. Through these experiences, they see the true meaning of friendship in Fairy Tail which is different from the competitive environment in Sabertooth.
Well, one possible plot could be that Tiamat arrives in the Fairy Tail world unexpectedly. At first, the Fairy Tail members might be on guard as Tiamat is a powerful and somewhat menacing figure. But then, Tiamat could turn out to have a noble reason for being there, like seeking help to stop an even greater evil that threatens both its own realm and the world of Fairy Tail. This could lead to an alliance between Tiamat and the Fairy Tail guild, with the members using their unique magic abilities in combination with Tiamat's power to face the new threat.
Perhaps Naruto is on a quest to find a way back to his own world. He realizes that staying in Fairy Tail is only delaying his journey. He has a sense of loyalty to his own friends back home like Sasuke and Sakura. So he leaves Fairy Tail, even though he has made some friends there, in order to pursue his ultimate goal of returning to Konoha.
Well, it could be that in this fanfic, Naruto is somehow transported to the Fairy Tail universe. And due to his different power set and origin, the Fairy Tail members misunderstand him and think he's a threat. Maybe they see his shadow clone jutsu as some sort of dark magic and turn against him.
One possible plot could be that Naruto is somehow transported to a world where Saiyan powers and Fairy Tail magic exist. He might start off as an outcast, not understanding these new powers at first. But as he trains and learns, he combines his ninja skills with Saiyan strength and Fairy Tail magic to become a powerful force and fight against an evil that threatens all three aspects of this new combined world.
Well, it could be about Naruto arriving in the Fairy Tail world and being shocked by the magic there. He might start to learn magic and use his ninja skills in combination with it. Maybe he teams up with Natsu and they go on adventures together, fighting powerful enemies with a mix of ninjutsu and magic.
Maybe the plot involves Naruto having a special connection to a fox - themed magic in Fairy Tail. He teams up with some of the Fairy Tail characters, like Natsu. Together, they go on adventures where Naruto's unique ninja - fox abilities from his own world combine with Fairy Tail's magic to defeat powerful enemies. For example, Naruto could use his shadow clone jutsu in combination with a fox - fire spell from Fairy Tail.
It could also be a situation where Naruto has his own motives that conflict with Fairy Tail's goals. Perhaps he discovers a power within Fairy Tail that he thinks is too dangerous and decides to take it upon himself to stop it, even if it means turning against them. He might think he's doing the right thing in the long run, but Fairy Tail sees it as a betrayal.
The plot could involve Naruto and Tayuya being mistaken for powerful mages in the Fairy Tail world. Since Naruto has such strong combat abilities and Tayuya has her unique skills. They get dragged into a guild - centered conflict. For example, there could be a rival guild trying to steal a powerful magic item that Naruto and Tayuya are somehow guarding or are associated with. They then have to use their combined skills, Naruto's ninjutsu and Tayuya's jutsu, along with the help of Fairy Tail mages like Natsu or Lucy to fend off the attackers.