Naruto could use his Four Tails form to fight a new and powerful enemy that the normal ninja of the Hidden Leaf can't handle. For example, an enemy with the ability to nullify regular chakra attacks.
One idea could be a story where Naruto has more control over his Four Tails form earlier than in the original series. He could use it to protect the Hidden Leaf in a new and unexpected way, perhaps by combining it with some new jutsu he's created on his own.
Kabuto could also be a good antagonist. After he gained all those powers and knowledge, he might target Naruto's six - tails form. He could use his medical ninjutsu to try and manipulate Naruto's transformation or even try to extract the power of the six - tails for his own use. Since he has the ability to mimic other ninja's techniques, he could be a formidable foe against Naruto in six - tails form.
The main character is Naruto for sure. But other characters like Jiraiya might play a significant role. Jiraiya could be the one to guide Naruto in controlling the four - tails' power. Also, characters from the Akatsuki might be main antagonists. They would be interested in Naruto's new power and try to capture or use him for their own purposes, like Pain or Itachi.
Well, a cool plot for Naruto six - tails form fanfiction might be about time travel. Naruto accidentally travels back in time while in six - tails form. He then has to figure out how to hide his form from his younger self and the people in the past. At the same time, he could use his knowledge from the future and the power of the six - tails to prevent some great disasters from happening in the past, which would change the future in unexpected ways.
One idea could be exploring the Four Tails' backstory more in - depth. Maybe it has a connection to an ancient ninja clan that was long forgotten. Another is a story where the host of the Four Tails has to team up with an unexpected ally to control its power.
No. Fanfiction should be about positive exploration of characters and their stories. Abusing a character like Tails is unethical and not in the spirit of fanfiction.
Well, in this fanfiction, it might be that Naruto's transformation into the four - tails form reveals some hidden secrets about the Nine - Tails' origin. This could lead to a whole new adventure as he tries to uncover more about it. Also, perhaps the four - tails form has a different set of abilities compared to what we've seen before, which makes for exciting battles and challenges for Naruto to overcome.
Well, there are several places. Firstly, Naruto - related forums often have sections for fanfiction. Members share their own works or recommend good ones. Another option is Reddit. There are Naruto subreddits where fans might post or discuss Four Tails fanfictions. You have to dig a bit, but it can be rewarding.
Character development can be shown through Naruto learning to control the Nine - Tails' power more precisely. For instance, at first, he might struggle and the power might be wild. But as the story progresses, he can gain more finesse, which shows his growth. Another way is his relationship with the Nine - Tails itself. If he starts off seeing it as just a power source and then comes to understand it as a sentient being with its own feelings, that's great development.