It could be a story full of adventure. Maybe they go on missions together as a married couple, using their combined skills to protect the village. Amaru's unique abilities and Naruto's ninja skills would make for an interesting dynamic.
In such a fanfiction, it might explore how their relationship changes the social fabric of the Hidden Leaf Village. There could be some resistance at first from the more traditional villagers, but Naruto and Amaru prove that their love is strong. It could also delve into how they balance their married life with their ninja duties. Amaru might support Naruto in his Hokage duties, and they could start a family of their own, with their children inheriting their powerful abilities.