Jiraiya could be one. Although he is known more for his fire and earth - based jutsu, he has vast knowledge and could guide Naruto in using water affinity in unique ways. Another could be Kisame. He is a master of water jutsu. His skills with water manipulation are top - notch, and he could teach Naruto some really powerful and advanced water techniques.
One potential mentor could be the Mizukage. As the leader of the Hidden Mist Village, they are likely to be very skilled in water jutsu. They could teach Naruto about the different forms and applications of water - based chakra. Also, there are some older ninja in the Hidden Leaf Village who might have been overlooked before but could have knowledge about water jutsu that they could pass on to Naruto.
A great fanfiction idea could revolve around the Nidaime's water affinity being passed down through generations. It could show how his descendants in the Hidden Leaf Village also had an inclination towards water - based techniques. The story could detail their struggles and triumphs in learning and mastering these jutsu, inspired by the Nidaime's legacy.
A fanfiction on this topic could explore how Naruto's godlike water affinity affects his relationships. For instance, Sasuke might be initially jealous of Naruto's new power but later realize they can work together. Sakura could use her medical ninjutsu knowledge to help Naruto better understand how his water affinity can be used for healing. And the village elders might be worried about Naruto's growing power and try to keep him in check. However, Naruto, with his kind heart, uses his power for the good of the village and to protect those he loves.
In Naruto, typically those with an affinity for water are often from certain clans or have a natural inclination towards it. In fanfiction, Naruto could be given a high water affinity to explore new plotlines. Maybe it's a result of some special training with a water - using mentor, or perhaps it's a hidden aspect of his Uzumaki heritage that was previously unknown.
Well, it could make him a more versatile ninja. He could use water jutsu to create powerful defenses like water walls, and also use water attacks that are difficult to dodge. For example, he could create water dragons that can pursue enemies. This new ability might also change his relationships with other characters. His teammates might rely on him more for water - based strategies in battles.
Naruto could use his godlike water affinity to communicate with water - based creatures. He might be able to understand the language of fish or water spirits. This could give him an edge in battles as he could call upon these creatures for help. For example, he could ask schools of fish to distract his enemies while he prepares a powerful water jutsu.
In some fanfictions, Naruto might be given high water affinity to add a new dimension to his powers. Maybe the author wanted to show his versatility. Since Naruto already has strong chakra control for his wind - style jutsu, extending it to water could make him an even more formidable ninja.
Naruto's high water affinity in fanfiction can be depicted in his battles. He might use water - style jutsu to outmaneuver his opponents in unexpected ways. His water attacks could have special properties, like being able to freeze on contact or carry a healing effect. And in some stories, his water affinity is so strong that he can manipulate the moisture in the air to create water for his jutsu, even in arid environments.
One cool jutsu could be the Water Spiral. Naruto would spin water around his body at a high speed, creating a protective and offensive spiral. Another could be the Water Mirror Clone. He creates clones made of water that can reflect attacks back at the enemy. And there's the possibility of the Water Tsunami, where he summons a huge wave of water to overwhelm his foes.
One way could be through unique jutsu creation. Since Naruto has such a high water affinity, he could develop jutsu that combine water with his existing wind - based Rasengan. For example, a Water - Rasengan that not only has the destructive power of the Rasengan but also the fluidity and adaptability of water. This would make him a more versatile fighter in battles against opponents who are strong against wind - based attacks.
Perhaps a plot point could be centered around the Nidaime training a young ninja with potential in water - based jutsu. He could pass on his knowledge and experiences related to his water affinity. This relationship between the mentor (Nidaime) and the mentee could be filled with lessons, challenges, and growth for both characters. For example, the young ninja might struggle with a particular aspect of water control, and the Nidaime has to find a unique way to help them overcome it.