Moon and the Sea

In the worst storm Maui has ever seen, an old friend of his is cast from the world of the gods and made to live as as demigod. Moana, who becomes Hina's newest friend, helps her adjust to living a life on the earth, and Maui's presence does not help her misunderstanding of how feelings for old friends can grow.
*A/U* Hina is sometimes depicted as Maui's older sister, but in this she is not, and you'll find out why ;)
But on the way, they find out the eel-god is preparing for a war against the healthy lands of the islands, and the trio which was once a pair must work to stop him.