A good plot might be that Naruto and Sasuke meet while on a mission to a far - off land. They encounter a strange new enemy that they have to defeat together. This would force them to rely on each other and strengthen their bond. They could also learn new jutsu from the local ninjas there and teach each other what they've learned.
One idea could be that Naruto and Sasuke meet in a peaceful alternate universe where there are no ninja wars. They could start a small business together, like a ramen shop. Another plot could involve them meeting during a festival in their village and rediscovering their friendship through fun activities like trying different festival foods and playing games.
In some fanfictions, they meet in a situation where Sasuke has lost his memory. Naruto then takes it upon himself to help Sasuke regain his memories and in the process, they go on various adventures together, facing different challenges that test their bond all over again.
One idea could be that they are in the alley hiding from some common enemy. In the heat of the moment, with the tension high, they share a kiss as a sign of their deep bond that has developed over time. It could be a moment of realization for both of them about their feelings.
In this fanfic, their meeting could also be in the context of a new threat to the ninja world. Naruto and Sauke would then have to put aside any differences or past grudges they might still have. They would combine their unique skills, Naruto with his Rasengan and Sauke with his Chidori, to face this new enemy. And along the way, they would strengthen their bond even more and show the world the power of their friendship.
One plot idea could be that they are ninjas in a world where their clans are feuding. To avoid causing more conflict, they keep their friendship a secret. Another could be that they are part of a secret organization within the ninja world that has strict rules about personal relationships, so they have to hide it. Maybe they are also trying to protect each other from enemies who would use their relationship against them.
One idea could be that Naruto and Sasuke find a mysterious baby in the forest. They then have to figure out where the baby came from and how to take care of it together. This could lead to some comical moments as they struggle with diaper changing and feeding.
One idea could be that the fused Naruto and Sasuke form has a new set of unique jutsus that combine their individual abilities, like a Rasengan with Sasuke's Chidori lightning. Another could be that their fused form has to face an enemy that neither of them could defeat alone, such as a powerful Otsutsuki clan member. Also, the fusion might struggle with the different personalities of Naruto and Sasuke, leading to some internal conflict and character development.
A fanfic could be set in an alternate universe where Naruto and Sasuke are normal kids in a modern world. They meet at school and become friends over their shared love for martial arts. They have to face bullies together, which strengthens their bond. This would be a fun take on their relationship, away from the ninja world.
The relationship can be developed through shared experiences. For example, if they go on a journey together and face difficulties like getting lost in a forest or running out of supplies. They would have to depend on each other to survive. Naruto could use his optimism to keep Sasuke's spirits up, and Sasuke could use his skills to protect Naruto.
A different plot could be that Sasuke meets Sakura at a medical convention in another village. Sakura is there to present some of her latest medical ninja research. Sasuke is initially there for other reasons but seeing Sakura makes him realize how much he has missed her and their connection.
A possible plot is that Sasuke is in a different dimension and Naruto has to figure out a way to travel there to save him. He might have to gather some special items or learn new jutsus to make it possible. Or perhaps Sasuke has lost his memories and Naruto has to help him regain them while protecting him from those who want to use his amnesia for their own gain. In some fanfics, Sasuke could be in a coma and Naruto uses his own chakra to try and wake him up, which could lead to some really emotional and intense scenes.