One common theme is the idea of a secluded and beautiful place (the waterfall) being a site for deepening the relationship between Naruto and Hinata. It gives them a private space away from the chaos of the village.
One possible plot could be that Naruto and Hinata go to the waterfall for a secret training session. Hinata has been struggling with a new jutsu, and Naruto offers to help her. At the waterfall, they face various challenges together, like wild animals and difficult terrains. This not only helps Hinata with her jutsu but also deepens their bond.
It might be a symbolic moment. The waterfall could represent the flow of emotions that are about to change between them. Naruto seeing Hinata there could signify that he is now ready to see what's been in front of him all along - Hinata's love for him. It's a way for the fanfiction to build up the relationship in a more romantic and meaningful way.
Well, in some fanfictions, when Naruto sees Hinata in the waterfall setting, it could be a moment of sudden realization. He might finally notice her in a new light, perhaps seeing her beauty and the depth of her feelings for him more clearly. It could be a turning point where he starts to develop deeper romantic feelings for her.
There's also a fanfiction titled 'Waterfall Confessions'. In this story, the waterfall serves as a backdrop for Hinata to finally gather the courage to confess her feelings to Naruto. It's a heart - warming read with a lot of emotional depth.