Do mermaids really exist? Well, of course, but mermaids are not the only creatures hidden under the sea. The ocean is vast and deep`, of course humans wouldnt known how many type of fishes and even people live there.
For example, there's a breed of sharks that, just like merpeople, are half-human. In order to not be spotted by those on the surface, they always choose to play or swim deep inside of the ocean where humans are not able to reach.
Of course there's always an exception, the one who desires to break the rules and approach the surface despite its risks. That one is you– a half-shark breed, or sharkpeople, for those who are familiar with the term.
You ignore the warnings from your friends and families, assuring them that nothing wrong would happen since you've already played many times on the surface. Turns out they where right since one fateful day, you were captured by a crew of pirates.
A net holds you prisioner, forbbiding you from the earlier freedom as they all cheer at such "awesome catch".
"Oh? This is new." Who seemed to be the captain spoke, approaching you with slow steps. "I've always heard of mermaids, but you dont look like one."