Jiraiya, if he were still alive in the fanfiction. He was Naruto's mentor and knew a great deal about the Nine - Tails. He might be able to use some of his toad - related jutsu or his knowledge of Naruto's chakra system to regain control over the Nine - Tails within Naruto. He had a deep bond with Naruto, which could also play a role in getting through to him.
The Hokage, depending on who it is at the time. They are usually very powerful shinobi. For example, if it's Kakashi, he could use his Sharingan and his vast array of jutsu to try and stop Naruto. He has experience dealing with powerful opponents and might be able to come up with a strategy to calm Naruto down or at least restrain him.
The consequences for Konoha's economy would also be significant. Rebuilding all the damaged infrastructure would cost a great deal of money. The trade within the village might be disrupted as well, since many of the shops and markets could be destroyed. Also, the ninja academy might have to be closed temporarily if it's damaged, which would affect the future generation of shinobi in Konoha.
Naruto's friends could also be of great help. Sasuke, despite their complex relationship, might have some knowledge or abilities that could contribute. Sakura, with her medical skills and her growth as a ninja, could support Naruto in his training. And even his other friends like Shikamaru, who is known for his intelligence, could come up with strategies for Naruto to better approach the task of controlling the Nine - Tails. The entire Konoha village in a way could also be seen as a helper, as it provides the environment and resources for Naruto's growth.
In some fanfictions, Naruto achieves complete control of the Nine - Tails through intense mental training. He might enter a special mental space where he has to face the Nine - Tails directly and prove his worthiness. By showing unwavering determination and a deep understanding of the power, he slowly gains the upper hand.
Another possibility is that the main antagonist is a group of power - hungry individuals who want to take Naruto's control of the Nine - Tails for themselves. They could be from within Konoha or from other villages. They might try to manipulate Naruto, or if that fails, they'll try to steal the Nine - Tails' power by force. They would likely be very skilled and have some devious plans up their sleeves.
In this fanfiction, Naruto probably has to first learn about the nature of the Nine - Tails' power. He may start by exploring his own family history related to the Nine - Tails. Then, he could encounter some challenges like the Nine - Tails' resistance to being controlled. But Naruto, with his determination, might find a way to communicate with it. For example, he could enter his mind - scape and have a direct conversation with the Nine - Tails. This could be a major turning point in his journey to control it.
Maybe through new jutsu or abilities. The fanfiction could give Naruto some unique power that allows him to communicate or negotiate with the Nine - Tails on a different level. He could use this power to show the Nine - Tails a different perspective, like the potential for harmony between them instead of constant struggle.
Iruka - sensei could be one of those who help Naruto. He has always been like a father figure to Naruto and would offer emotional support. Rock Lee could also be a great helper. Lee, who has trained his body to be extremely powerful, could teach Naruto some physical combat techniques that don't rely on eyesight. And of course, the Nine - Tails inside Naruto might also play a role. It could potentially share some of its power or knowledge to help Naruto deal with his new situation.
Yes, in some fanfictions, Naruto is often depicted as having a very special connection to the Nine - Tails that goes beyond the normal relationship in the original story. For example, he might be able to fully control the Nine - Tails' power in ways not shown in the canon, or they could have a mental bond that allows for unique forms of communication and cooperation.
One possible plot development could be that Naruto uses his new - found control of the Nine - Tails to defeat a powerful enemy that was previously unbeatable. He might be able to combine his own ninja skills with the Nine - Tails' power in a more efficient way, like creating new and unique jutsu.
Well, the Nine - Tails itself can be considered a popular 'character' in this type of fanfiction. It has its own personality and power, and many stories revolve around Naruto's interaction with it. Another character that might be popular is Gaara. Since he also has a tailed beast within him, there could be interesting interactions between him and Naruto regarding their respective tailed beasts, especially when it comes to the Nine - Tails.