Well, perhaps Naruto enters the Fairy Tail universe during a time of great crisis. His determination and never - give - up attitude inspire the Fairy Tail members. He could form a special team with Natsu and others. They'd go on quests together, and Naruto's ability to sense danger and his strategic mind would be a great asset. Also, his Nine - Tails chakra could be a new form of power that the magic world has never seen before, leading to all kinds of interesting plot developments.
A possible storyline could be that Naruto is mistaken for a powerful lost mage in the Fairy Tail world. As he tries to clear up the misunderstanding, he gets involved in the guild's internal politics. He might have to prove himself to the guild master. Along the way, he befriends the guild's members, and his badass nature starts to rub off on them. His experience with fighting powerful foes in his own world would give him an edge in battles against Fairy Tail's enemies, and his story could become intertwined with the guild's future.
In some fanfictions, there might be a tournament - style event at the Fairy Tail Academy. All the students get to show off their unique skills and magic. The underdog characters, those considered not so strong initially, might surprise everyone with their hidden talents and strategies. This kind of storyline creates a lot of tension and excitement as you cheer for your favorite characters.
One possible storyline is Naruto joining Fairy Tail and using his immortality to protect the guild from powerful enemies. He could take on dangerous missions without the fear of death. Another could be that he tries to find a way to reverse his immortality because he misses the normal cycle of life and death. Or perhaps he becomes a mentor to the younger Fairy Tail members, teaching them his ninja wisdom along with his unique immortality - related skills.
One storyline might involve a young Fairy Tail novice who discovers they have an innate ability similar to Wood Release. This ability sets them apart from their peers and they face both envy and admiration. They have to journey to find out the origin of this power, which leads them to uncover secrets about a long - forgotten connection between their world and Naruto's. Along the way, they face many challenges and grow stronger, all while trying to master their unique Wood - like magic.
One possible storyline could be that Natsu is wrongly accused of a crime within the Fairy Tail guild. Maybe some false evidence is planted against him, leading the guild members to turn their backs on him. Another could be that a powerful enemy manipulates the guild into believing Natsu is a threat, so they betray him. It might also be that there's a misunderstanding about Natsu's powers or intentions, causing the betrayal.
One possible storyline could be Natsu founding Fairy Tail after a great battle where he realizes the need for a guild that stands for true friendship and strength. He then gathers like - minded mages and builds the guild from the ground up.
One popular storyline could be a character from Naruto ending up in the Fairy Tail world and getting involved in a harem situation. For example, Naruto himself might find that he has a group of Fairy Tail female characters who are attracted to his unique abilities and strong will. Another could be a crossover where characters from both universes have to work together in a mission and a harem dynamic develops among them during the adventure.
In some fanfictions, Natsu could be framed by a dark guild as a traitor to Fairy Tail. The dark guild spreads false rumors and evidence, causing Fairy Tail to turn against him. Natsu then has to prove his innocence while also taking on the dark guild that started it all. This would lead to a lot of internal conflict within Fairy Tail and also intense battles between Natsu and the dark guild members.
One interesting storyline could be where Naruto characters end up in the Fairy Tail world and vice versa, and they form a harem. For example, Naruto might meet Lucy from Fairy Tail and they start an adventure together, gradually attracting other characters into their group that develops into a harem. This could involve them facing common enemies from both universes.
One interesting storyline could be Naruto using the Sharingan to copy the magic of Fairy Tail wizards. He could then combine his ninja skills with the copied magic, creating unique fighting styles. For example, he might copy Erza's requip magic and use it to quickly change his ninja tools during battle.
One popular storyline could be a crossover adventure where Naruto and the Fairy Tail characters, especially with Mavis involved, team up to fight a common, powerful enemy. Maybe an ancient evil that threatens both their worlds.