Here is an adopted I got from  GinMizuki of Marie the mer rabbit who was once a land rabbit :)

Marie was once lived on the surface and part of a group calling themselves the 'hunters' who goes about to hunt merfurs yet it is extremely rare they would come across one. Marie past was mysterious until she met with a certain merhorse and after a night of intimate, she soon decided to leave her old life on land and become one with the sea by being a merfur.

She soon settle in the City of Poseidon where she became in love with both the merhorse and his brother and music of the deep. She became a muscian and plays the violin and would travel to clubs and stage to perform her new found love of undersea music. She hasn't forgotten how to fight though now she would rather play music than fighting (if needed). a lovely merrabbit who sole goal is not only protect those from her old group, but to bring joy to others under the sea and to know about her past