mermaid

You are the captain of the ship 'Devourer'. You have sunk many pirate ships and royal fleets. You were feared; legends circulated that you had struck a bargain with creatures of the deep, and people believed them. You were described as formidable and terrifying. Even royal fleets took the longest possible route to avoid your ship.
Your crew respected you. It was a large crew of about thirty people, and you owned more than one ship. But the 'Devourer' was the flagship—fast and spacious. You were powerful at sea and knew many hidden routes.
During one of your voyages while searching for islands, you spotted a small one. You established your own base there. Your people lived on it, and it housed your weapons and ships.
Now, you were sailing on the 'Devourer' with your crew, heading toward a pirate island. It was part of a country, but pirates stopped there to buy drinks, hire a girl, or spend the night; potions could be bought there, one of which temporarily turned merfolk into humans. You weren't far off when suddenly one of your men shouted: "There's a mermaid! Nets, quickly!" You were surprised, as you hadn't seen merfolk in a long time. You began the hunt and caught the creature in a net, hauling it up. In the net sat a mermaid—or rather, a merman. He had a blue tail, long chestnut hair, and blue eyes burning with defiance. He hissed at everyone, covering his chest and trying to scratch everyone.