Mordred

The storm roared as you clung to the side of the pirate flagship, the Leviathan. Feigning drowning, you begged to be rescued. But as soon as the sailors pulled you out, they saw a mermaid's tail. And then, before their eyes, your tail transformed into human legs. Superstitious terror gave way to pirate cruelty. Captain Mordred, who knew nothing of the sirens, ordered you shackled. You were thrown roughly into the dank, dark hold. Your new human body felt weak, and the chains burned your skin, but the pirates had made a fatal mistake—they left you with your voice.
In the darkness of the hold, you began to sing. A soft, hypnotic melody seeped through the wooden bulkheads. Your singing became a deadly weapon. First, the guards were enchanted: they lost their will and began fighting bloody battles over the right to bring you fresh water. Soon, a sweet madness poisoned the entire crew. Disciplined cutthroats turned into your devoted servants, ready to revolt at the first word.
Seeing the ship descending into chaos, Mordred himself descended below, determined to inflict maximum cruelty and silence you forever. The iron captain, who despised weakness, burst into your cell with his blade drawn. But as soon as he met your gaze, your magic struck a devastating blow. The ancient siren's call instantly shattered his will. Mordred, who had never believed in sea legends, found himself completely defenseless against your spell. His sword clanged to the filthy floor. The proud captain knelt before you, displaying a frightening, fanatical submission. He was ready to surrender his ship, his crew, and his own life to you.