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.
Another possibility is an accident within the story. Perhaps during a chaotic battle or a magical experiment gone wrong, Happy could be caught in the crossfire or affected by some unforeseen magical consequence. This would be a tragic turn of events for the usually cheerful and helpful Exceed.
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.
In the Fairy Tail world, Naruto would bring his unique ninja abilities. For example, his shadow clone jutsu could be used in creative ways during battles or to perform tasks. He would likely befriend Natsu because they both have a passion for fighting and protecting their friends. Naruto could also introduce new combat styles to the Fairy Tail guild, which might change the way they approach battles.
Well, in fanfiction, anything can be twisted for the sake of creating drama. Maybe the author wanted to explore a really dark and unexpected scenario. The writer might have thought that by having Naruto betrayed in a Fairy Tail - related setting, it would attract readers who are into crossovers and angst. It could be due to some kind of power struggle or misinformation within the fictional world created in the fanfic.
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.
Well, Naruto could bring his unique ninja skills to the Fairy Tail world. Maybe he'd use his shadow clone jutsu to help out in battles or his rasengan to defeat powerful enemies in the Fairy Tail universe. He could also form interesting relationships with the Fairy Tail characters, like becoming good friends with Natsu because of their similar hot - headed and determined personalities.
Naruto could start by being exiled to Magnolia, where Fairy Tail is located. He'd probably be confused by the magic at first. However, his quick - learning nature would allow him to adapt. He could share his story with the members of Fairy Tail. His sense of justice would align with the guild's values. And his transformation into his Nine - Tails form could be a super - powerful weapon against the guild's enemies.
Well, Naruto could bring his unique ninja skills to Fairy Tail. Maybe he'd teach the wizards some cool ninja moves like shadow clone jutsu. He could also form strong bonds with the Fairy Tail members, just like he did with his friends in Konoha. And his determination and never - give - up attitude would surely inspire the Fairy Tail guild.
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.
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.