Cursed (billdip)

Dipper is not exactly a common siren living in the ocean. Her family is curse every other four generations a child is curse. Dipper and her sister are cursed with amazing voices people would die for and fantastic looks. But when the king and prince of the sea come to her village looking for a bride for the prince everyone is excited but her. Some girls her age have already found mates. Mabel was dating mermando. But when she is chosen to be the bride what will happen when she is kidnapped and sold to a land kingdom. Will she return home?

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I am making this up but go with it.
Dipper is a female siren. Mabel is a mermaid.
The difference is sirens are carnivores. Mermaids are omnivores (plants and meat). Sirens have two feet longer of a tail than mermaids because sirens tend to strangle their pray while singing, their tail is more snake like while mermaids have a more fish like tail.