Well, perhaps a great plot twist is that Naruto's immortality is actually a curse in the Fairy Tail universe. The magic there has a different set of rules, and his inability to die disrupts the natural balance. This could lead to him being hunted not just by villains but also by some of the more morally strict magic guilds. Also, imagine if Naruto discovers that his past enemies in the Naruto world are somehow connected to an ancient evil in the Fairy Tail world, and he has to fight them again in this new context.
A really cool plot twist might be that the Fairy Tail guild discovers a prophecy about an immortal from another world (Naruto) who will either save or destroy their world. This causes a split within the guild, with some believing Naruto is the savior and others thinking he's a threat. And Naruto, being Naruto, tries to prove he's there to help while also dealing with his own issues related to his immortality, like missing his old friends from the Naruto world and trying to find a place where he truly belongs in the Fairy Tail world.
A great plot twist would be if the Fairy Tail guild members were transported to the Naruto world and had to adapt to ninja life. Or perhaps a character from Naruto, like Sasuke, gets corrupted by the dark magic in the Fairy Tail world. It would create a whole new dynamic as the other characters try to save him. Also, what if there was a prophecy in both worlds that the only way to save them was for a Fairy Tail wizard and a Naruto ninja to sacrifice themselves? That would be a very intense plot twist.
One interesting plot twist could be Sakura having to adapt to Fairy Tail's magic system. Maybe she discovers a new form of her own chakra-based abilities that interact with Fairy Tail magic in unexpected ways. For example, her healing jutsu could combine with Fairy Tail's healing magic to create a super - healing spell.
One interesting plot twist could be when the magic from Fairy Tail interacts with the sins' powers in Nanatsu no Taizai. For example, if Natsu's fire magic somehow combines with Meliodas' full counter, creating a new and unexpected power. Another could be the characters being transported to the opposite universe and having to adapt. Like Lucy ending up in Britannia and having to deal with the Holy Knights while the Seven Deadly Sins end up in Fiore and face off against the dark guilds.
One interesting plot twist could be that characters from Fairy Tail end up in the world of Legend of Zelda and they discover that their magic has a completely different effect. For example, Natsu's fire magic might interact with the magical elements in Zelda's world in a way that either helps or hinders their quest. Another could be that the Triforce has an unexpected reaction to the Fairy Tail mages' presence, perhaps granting them new powers or cursing them. A third plot twist might be that a major villain from Legend of Zelda teams up with a dark guild from Fairy Tail to take over both worlds.
Another plot twist might be that the villains in the Fairy Tail world are the ones who summoned Godzilla, but they lose control of it. Now the Fairy Tail guild has to figure out a way to stop Godzilla while also dealing with the villains who caused the mess in the first place. It adds a layer of complexity to the story.
Well, a great plot twist might be that the characters from Fairy Tail end up in the world of Fullmetal Alchemist and are mistaken for some sort of alchemical creations. They then have to prove that they are not and in the process, they discover that their magic has some strange effects on the alchemy in that world. For example, Gray's ice magic could freeze alchemical reactions in unexpected ways. Another plot twist could be that the Gate in Fullmetal Alchemist has a link to the Fairy Tail's Celestial Spirit World. So when someone tries to open the Gate, they accidentally open a portal to the Celestial Spirit World instead, and all kinds of chaos ensues as spirits and alchemists meet for the first time.
The cultural exchange. Naruto characters come from a world of ninja clans and strict hierarchies, while Fairy Tail has a more guild - based, family - like culture. Seeing how they interact and influence each other, for example, a Fairy Tail member learning about the Uchiha clan's history from a Naruto character, is really engaging.
A great plot twist could be that Alice is actually a long - lost Fairy Tail mage. Maybe she was sent to Wonderland as a child and lost her memories. Another one is that the Queen of Hearts in Wonderland is being controlled by a dark mage from Fairy Tail's world. It would turn the whole story on its head.
The most interesting aspects? Well, for starters, Naruto's immortality allows for long - term character development in the Fairy Tail setting. He can build relationships over a long period, like befriending Natsu and the others. His unique abilities like shadow clones could be combined with magic in unexpected ways. Also, his backstory as an outcast in his own world and then coming into a new world as an immortal could lead to some deep exploration of his character and how he adapts, which is really fascinating.
In a Naruto and Ben 10 crossover fanfiction, an exciting plot twist could be that the DNA of the aliens in Ben's Omnitrix starts to mix with the chakra in Naruto's world. This could result in new forms for both Ben and Naruto. For Naruto, he might gain the ability to transform into a half - alien, half - ninja hybrid with unique powers. Ben, on the other hand, could find that his alien forms now have chakra - based abilities. This would not only change their powers but also how they interact with their respective worlds and enemies.