Kakashi would also work well. His vast experience and his Sharingan would be useful in guiding the six - tails jinchuriki. He could teach the jinchuriki how to better control their chakra and how to use the power of the six - tails in a more strategic way. Plus, their interactions could lead to some interesting story arcs, like Kakashi having to step in when the six - tails' power goes out of control.
Sakura could be a great choice. She has strong medical ninjutsu skills and a no - nonsense attitude. She could help the six - tails jinchuriki when they get injured during battles against the power of the six - tails or external enemies. Also, her growth as a character could be further explored as she tries to understand and support the jinchuriki.
Rock Lee could be an interesting pairing. Lee's dedication to training and his unique fighting style could inspire the six - tails jinchuriki. They could train together, with Lee helping the jinchuriki to build physical strength and discipline, which in turn would help in controlling the six - tails. And their friendship could develop as they face challenges together, like competing in a high - stakes ninja tournament.
One idea could be the six - tails jinchuriki's struggle to control the power. For example, they constantly have to battle the inner urge of the six - tails to go on a rampage. Another plot could involve the jinchuriki being hunted by an evil organization that wants to extract the six - tails' power for their own malicious use. They would then have to fight and outwit this organization while also dealing with the social ostracism that often comes with being a jinchuriki.
Often, other Naruto characters like Naruto Uzumaki or Kakashi Hatake might be included in the two - tails jinchuriki fanfiction. Their interactions with the two - tails jinchuriki can create new and exciting plotlines, whether it's them helping the jinchuriki control their power or going on adventures together.
Yugito Nii is a very popular character as she is the actual 2 - Tails Jinchuriki in the Naruto series. In fanfiction, she often takes center stage, whether it's in stories about her training or her battles against powerful foes.
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.
One interesting story could be about the two - tails jinchuriki's journey to control the beast's power. Maybe they face a powerful enemy and have to learn to use the two - tails' abilities in a new way to defeat them.
Sasuke could be a main character in a Naruto 11 Tails Fanfiction. He has always been Naruto's rival and equal in many ways. His skills and knowledge of the ninja world could be crucial in dealing with the 11 - tails. Maybe he would have a different perspective on how to handle the situation compared to Naruto.
It could be a new ninja who has a special ability to sense the Zero Tails. This ninja might be an outcast in their village because of this strange ability, but it turns out to be the key to dealing with the Zero Tails.
The relationship could be a complex one. At the start, the Jinchuriki may not even be aware of the Five Tails Gobi's presence, but as they start to notice strange things happening within themselves, they begin to explore the connection. The tailed beast could be initially hostile, seeing the Jinchuriki as a weak host. However, as the Jinchuriki faces various challenges and grows stronger, the Five Tails Gobi starts to see potential in them. This could lead to a transformation in their relationship, from one of enmity to one of begrudging respect, and eventually to a deep and symbiotic bond where they rely on each other for survival and the protection of the ninja world.
It could be Orochimaru. He's always been after power and Naruto having the power of two Bijuus would be very tempting for him. He might try to extract the Bijuus from Naruto to use for his own evil purposes.
Sakura could be a potential member. She's strong - willed and has her own set of skills. Hinata is also a possibility as she is kind and has always had feelings for Naruto. Ino could be in the harem too with her mind - related abilities. And Tenten, with her weapon skills, might also be an interesting addition.