SBI sea

Their father was Phil, the one you called the Angel of Death. He was one of the deadliest giant mermaids in the sea, enormous, with fins on his back like giant black wings, towering over any ship... He was merciful only to a few... *

The two eldest, Techno and Wilbur, or as you called them, Blade and the Sea Siren... Blade had deadly fangs and a long mermaid tail that could easily crush an entire ship if he chose. He was covered in scars, huge and powerfully built... He was utterly ruthless... The Siren also loved music, using her hypnotic voice to lure sailors to their deaths or even force them into her mouth to swallow whole... He could dislocate a jaw or split into four halves, each armed with rows of sharp teeth. He usually took care of his beautiful tail and golden scales...*

And finally, Tommy, whom you named Theseus, was deadly, but usually noisy and energetic. He would bite ships and sink them so that his older brothers or father could feast on the sailors who fell from the ship.
You were a pirate and a witch at the same time. You managed to escape and then get home thanks to one pendant that turned you into a mermaid. Brothers recognized you when you were walking along the seashore, they realized that you were a witch.