With the Rinnegan, Naruto could also gain the power of the Human Path. This might allow him to read the minds of his opponents or extract information from them in a very unique way. He could also use the Naraka Path to torture his enemies psychologically, which is a very dark but powerful ability that the Rinnegan offers.
With the Rinnegan, Naruto might gain the power of the Human Path. This would allow him to read minds or rip out souls, which is a very dark and powerful ability that would be quite different from his usual positive - natured powers.
With the Rinnegan, he could have abilities like the Six Paths techniques. He might be able to use the Preta Path to absorb chakra attacks. And with the Hyoton, he could create ice - based jutsu that are much more powerful than normal ice jutsu, like freezing an entire area instantly.
He could have the ability to use all six paths techniques right from the start. This means he could manipulate gravity like the Deva Path, absorb chakra like the Preta Path, and even revive the dead like the Outer Path.
Naruto would likely gain the ability to use all six paths techniques. The Rinnegan allows the user to manipulate gravity, as seen when Madara used it. Naruto could use this to enhance his combat skills, for example, pulling enemies towards him or pushing them away forcefully. He could also use the Preta Path to absorb chakra, which would be a great addition to his already large chakra reserves.
A new ability could be the use of genjutsu, which Naruto has not been proficient in before. However, the challenge would be that using the Sharingan drains his chakra more than usual. As Naruto is used to his own chakra - intensive techniques, this could put a strain on his energy reserves during long battles.
His character would have a darker edge. The vampire nature could bring out a more primal and possessive side. And the Rinnegan would give him new levels of power and knowledge. He might start to question his old values as he realizes the potential of his new powers. He could become more solitary, training alone to master his combined abilities rather than relying on his friends like he used to.
In a fanfiction where Naruto has the Rinnegan, it might change his relationships too. His friends could be both in awe and a bit scared of his new power. The villages might see him as an even greater threat or a more reliable protector. Also, his training would have to be different. He'd need to learn how to control and master the Rinnegan's abilities, which are very different from the chakra nature he was used to.
With Kakashi, Naruto having the Rinnegan could change their teacher - student dynamic. Kakashi would be both amazed and a bit worried. He would need to guide Naruto in a new way, as the Rinnegan brings a whole new set of powers and potential dangers. Naruto might start to teach Kakashi some things he discovers about the Rinnegan, reversing their roles to some extent.
Naruto's Rinnegan abilities in a Fairy Tail fanfiction would likely disrupt the status quo. The Rinnegan - granted power to control the Tailed Beasts would be an interesting aspect. In Fairy Tail, there are no Tailed Beasts, but perhaps Naruto could use that power in a different way, like controlling powerful magical creatures. His Sharingan - like abilities within the Rinnegan, such as predicting movements, would also give him an edge in battles against Fairy Tail wizards. And his Rinnegan could potentially unlock new forms of magic for him, as it has the ability to unlock hidden potentials in Naruto's own world.
Maybe he would gain the ability to control the life force of others in a new way. With the red Rinnegan, Naruto could potentially heal or harm on a much greater scale. He could revive the recently deceased by restoring their life force, or he could drain the life force of his enemies to weaken them. This would be a huge shift from his normal abilities and add a new moral dimension to his character as he decides when and how to use such a power.