A Mermaid's Story

This is a world where mermaids exist. This is a story on how they were formed. In this one, you'll follow the life of a girl's journey into a mermaid and her path for revenge for the pirates on the ship Winter Mark who tried to kill her for being a woman cursing them for being aboard. Will she succeed or will her path be changed forever?
(This is in an alternate world, some things are like our world but not all.)