Still would love to find some new lines. It doesn't really have to involve this mermaid muse right here.
I have two ideas I would love to do apart from the mermaid theme.
The first one would be a famous cellist who is blind though. She basically lives for her music and her concerts. He has his own band and plays mostly rock songs. One night she can hear him sing at a small cafe/venue etc. and she's absolutely in love with his voice. They get to talk but she's ushered away by one of her management people. A few days later, he's sitting in one of her concerts even though he's not a fan of classic music at all. We could go from here...
The second idea would be kidnapping. The king's daughter had been kidnapped at the age of 4 months. The king never recovered from the loss. His wife died during the birth of his only daughter. He married another woman and has now 3 daughters. But they are all spoilt little brats and when the King of France travels to pick a wife for his son, he's more than disappointed. Ironically, the king's daughter lives nearby in a very poor but very loving family. They prepare cakes and sweet desserts for the French King and his entourage. That's when the attention from the young French prince shifts to the little bakery girl.