(May be a little late, but I found this on some old folders, it´s about Penny´s curse)
From the diaries of Dr. Harvey Coulson:
"Acording to my studies, from what I could find by asking the locals and some old leyends, I managed to stich up this story, including even the tiniest details… which is most likely what really happened…"
A long time ago, most likely on the 18th century, a witch fell in love with a fisherman, day by day, she hid between the barrels filled with fish and watched him go to the sea, she didn´t knew his name, only his face and his voice, the voice she fell in love with, that gorgeous voice that couldn´t be human yet… it was coming from one. She did that for years, until one day, the man didn´t show up, the witch worried, searched trough all the village, only to find him entering a house, his face exited, almost in tears. The witch hid between the bushes , not brave enough to talk with the man, when he was finally in, she came closer to the window, being as careful as she could, watching him aproach a woman lying on a bed, with a child on her arms, as the words "It´s a beautiful girl" came out of her mouth. It couldn´t be, the man she loved for all those years was married, he had a family, she watched as the rest of his children, two young boys, came rushing to the room.
The witch enraged with her heart broken, went and atacked the man, collecting part of his blood, while doing so. She ran, trying to keep herself alive as the man and the whole village followed her, then, as the last thing she did, before being killed, she cursed them, every female descendant of the man was going to have the same beautiful, yet haunting voice that could drive anyone insane, that could control people, each one of them was cursed to be a fish-like abomination that crave for human flesh, each one of them, starting from that little girl she saw, as she grew older, her hair fell out, her skin began to grow scales, she grew gills, her eyes were wider, she grew claws and sharp teeth, and the last thing she asked was to be killed. From that day, each female descendant of that family has been killed since the moment they are born, since none of them is born human, no more.