Who could be responsible for Naruto getting sealed away in a Fairy Tail fanfiction?

There's also the possibility that it was an accident. Some kind of jutsu gone wrong during the sealing process. The person performing the sealing might have been inexperienced or there could have been some unforeseen interference that led to Naruto being sealed away instead of the Nine - Tails being properly sealed within him.

In such a fanfiction, the Fairy Tail guild might be thrown into chaos. They could initially be confused about this strange event from another world. Some members might see Naruto's sealing as a threat to their world's balance, while others might be more curious and try to find a way to break the seal.

One possible reason could be that his godlike powers were seen as a threat. The village elders or some powerful forces might have feared that Naruto, with his immense strength, could lose control and cause destruction. So, they decided to seal him away to protect the village and the world at large.

A corrupt leader from a political - based crossover world might be the main antagonist. He views Naruto as a threat to his power, especially with the mystery of his seal. So, he tries to either keep Naruto sealed away permanently or use the situation to gain more control over his own people by creating fear around Naruto's presence in their world.

Another option is that a new character introduced in the crossover could be the main character. For instance, in a Naruto - Fullmetal Alchemist crossover, an alchemist from the FMA world could stumble upon Naruto's sealed state and make it their mission to free him, while also getting involved in the politics and power struggles of the Naruto world.

It could be Orochimaru. He might have learned about the Avatar's unique power and wants to use it for his own dark experiments. So he tries to break Naruto's seal to get to the Avatar. He would be a great villain as he's always after powerful things and doesn't care about the consequences.

The main antagonist could be a new character created specifically for the fanfiction. This character might be from a long - lost clan that has a grudge against the Uzumaki clan, of which Naruto is a part. Since Naruto is the last of the Uzumaki in the village, sealing him away would be their first step in getting revenge on the clan, and they would do everything in their power to keep him sealed.

Another possibility is that it's a rogue Shadowhunter. There are always those in the community who don't agree with the way things are going. If Clary's actions or ideas are seen as too radical, this rogue Shadowhunter might try to stop her by injuring her. This could also lead to a story about Clary trying to understand the motives of this attacker and potentially reform them.

The story could also focus on the efforts to unseal Naruto. His friends and the characters from the crossover world could embark on a dangerous journey to find the key or the magic to break the seal. In a Naruto - Harry Potter crossover, Hermione might use her vast knowledge of magic to research a way to free Naruto from the seal.

One possibility is that the story could focus on how the village copes without Naruto. Maybe there would be a different kind of unrest or a search for a new way to deal with the Nine - Tails' power. Without Naruto, characters like Iruka might have a different role, perhaps becoming more involved in trying to find a solution to the power void.