In the context of this fanfiction, it could be that a powerful enemy in Konoha manages to frame Naruto for a heinous crime. As a result, he is banished. When he arrives in the Fairy Tail world, he might initially struggle to adapt as it's a completely different culture with magic instead of chakra. However, his determination and strong will, which are his trademarks in the Naruto series, would help him overcome the challenges and eventually find his place among the Fairy Tail guild members.
Perhaps in this fanfiction, Naruto's power is seen as a threat in Konoha. His connection to the Nine - Tails or his unorthodox ninja ways might not be tolerated. And Fairy Tail is a place that welcomes misfits. So, he gets banished from Konoha and finds his way to Fairy Tail. There, he could learn new magic skills and form new relationships, which would be a great twist on his original Naruto story.
He would bring his unique ninja skills. For example, his shadow clone jutsu could be adapted into some kind of magic - like ability in the Fairy Tail world. His strong sense of loyalty and friendship would also influence the Fairy Tail members. He might inspire them to be more united and fight more fiercely for each other.
In this fanfiction scenario, Naruto could save Fairy Tail from Acnologia using his powerful jutsu. For example, his Rasengan or Sage Mode abilities might be enough to fend off Acnologia. Maybe he could also use his shadow clone jutsu to distract the dragon while Fairy Tail members prepare a counter - attack.
Well, perhaps in this fanfiction, Naruto is banished due to a false accusation in his world. He lands in the Fairy Tail world and is seen as an outsider. However, his determination and strong will attract the attention of some of the Fairy Tail members. Erza, for example, might see his potential and take him under her wing, training him in the ways of the Fairy Tail magic while he also teaches her some ninja tricks.
In fanfiction, Naruto could become the founder of Fairy Tail by having his unique ninja skills and values influence the creation of the guild. Maybe he travels to the Fairy Tail world and decides to gather like - minded mages. His leadership skills, learned from being a ninja, would help him in setting up the guild's rules and training methods.
Perhaps it's a matter of a powerful enemy from Fairy Tail's lore recognizing Naruto as a significant threat and using a very underhanded or extremely powerful attack on him. Since Naruto might not be fully aware of all the rules and powers in the Fairy Tail world, he could be caught off - guard. And in fanfiction, the writer might want to create a very dramatic and unexpected death for the sake of a unique story, so they come up with a scenario where Naruto dies in the Fairy Tail world.
In this fanfiction scenario, Naruto could leave Konoha due to some sort of misunderstanding. Maybe the people of Konoha in the Fairy Tail world suspect him of being too dangerous with his unique abilities. So, he leaves to prove himself elsewhere, perhaps by joining a different guild or team in the Fairy Tail world that is more accepting of his different nature.
One possible reason could be fear. Naruto's 'godlike' powers might be too much for the village to handle. They could be afraid that he might accidentally cause destruction. Another reason might be envy among some of the villagers or ninja. They may not like that Naruto has become so powerful all of a sudden and want him out of the way.
One possible reason could be false accusations of a serious crime. For example, if he was wrongly blamed for a major attack on the village. Another reason might be political intrigue. Some powerful figures in the village might see Naruto as a threat to their power and find a way to banish him to maintain their control.
The main antagonist could be a powerful demon that has been sealed in the Fairy Tail world for a long time. Naruto's arrival disrupts the seal somehow, and the demon sees Naruto as a key to fully breaking free. The Fairy Tail members and Naruto must put aside their differences and combine their powers to fight this demon.
It could be that the fanfic writer is trying to combine the two universes in a rather dark way. In Fairy Tail, there are all sorts of magic and temptations. If a character from Naruto's world gets involved with someone from Fairy Tail, they might be easily cheated on. For example, if a Fairy Tail character has a magic ability to manipulate emotions, they could use it to deceive Naruto's character.