A really cool plot could be that Naruto and Kyuubi have to enter the minds of the villagers who once feared Kyuubi. They use their friendship as a tool to show the villagers that Kyuubi is not a mindless monster but a being with feelings and a capacity for good. They work together to change the perception of Kyuubi within the village, which helps to strengthen the bond between the village and Naruto even more.
In a fanfiction, Naruto and Hinata as friends could go on a journey to find a rare flower that has the power to heal serious injuries. They encounter various obstacles like dangerous terrains and wild animals. Hinata might use her tracking skills with the Byakugan to find the right path, and Naruto would protect them from any immediate threats. As they travel, they talk about their dreams and fears, deepening their bond of friendship.
One interesting plotline could be Naruto gaining new and powerful abilities after the merge. For example, he might be able to access a new form of chakra that combines his own with the Kyuubi's. This could make him nearly unbeatable in battles against strong foes.
One interesting plotline could be Naruto gaining new and unique powers from the merge. For example, he might be able to access a special form of chakra that combines his own with the Kyuubi's, allowing him to perform super - strong jutsu. Another could be how his relationships with his friends and allies change. Maybe some are initially afraid of his new power, but he has to prove that he's still the same Naruto at heart.
Some fanfictions focus on the idea of a different kind of seal being used on the Kyuubi. Maybe a more humane or symbiotic seal that allows Naruto to fully utilize the Kyuubi's power without the negative side effects. This can lead to a whole new Naruto, one who is more in control and perhaps even more powerful than in the original story.
One interesting plotline could be Naruto gaining new and unique powers from the fusion. For example, he might be able to access a new form of chakra that combines his own with the Kyuubi's. This could make him even more powerful in battles against tough opponents like Pain or Madara.
One plotline could be the Kyuubi teaching Naruto some ancient and powerful ninja techniques that were lost over time. Since the Kyuubi has been around for a very long time, it has a wealth of knowledge. Another could be Naruto and the Kyuubi having to team up to face a new, powerful enemy that neither of them could defeat alone.
Another interesting plotline is that the Kyuubi eye gives Naruto the ability to communicate with the spirits of past Jinchuriki. They teach him ancient techniques and give him insights into the true nature of the tailed beasts. This new knowledge makes him an even more formidable force, but also makes him a target for those who fear the power of the Jinchuriki.
Well, perhaps a plotline where Naruto, reborn as the Kyuubi, has to deal with the reactions of his friends and former enemies. His friends might be initially scared or distrustful, while his enemies might see him as an even greater threat. This could lead to a lot of conflict and character development as Naruto tries to prove that he's still the same person deep down.
One possible plotline could be the Kyuubi teaching Naruto unique and powerful jutsu that he can't learn from his normal training. Another could be the Kyuubi helping Naruto understand his own heritage and the secrets of the Uzumaki clan in a more in - depth way. Maybe also the Kyuubi guiding Naruto to control his chakra better in a way that no one else could teach him.
One possible plotline could be Naruto suddenly gaining the Sharingan through some mysterious jutsu accident. With the Sharingan, he could quickly learn new techniques and have enhanced perception. Combined with the Kyuubi's power, he might become an almost unbeatable force. For example, he could use the Sharingan to better control the Kyuubi's chakra flow, making his attacks more precise and powerful.