>>334813
>tfw I have read Selkie story where young man kills seal (major taboo in his community) to use it's hide to dive treasure from sunken ships. Doing that ends up alping him into Selkie and realizing that same thing most likely happened to his grandmother who told him how to dive with seal hide. (S)he ends up marrying former bro, has his child and saves him from storm after their child discovers seal pelt that bro hid away to prevent the alp-Selkie from escaping to sea
It was rather vanilla/heartwarming other than the genderbending part.