She was once a seapony, but sold her voice to Grogar as mentioned in the Creation of the Sirens to gain the ability to walk on land for ever, not realizing at the time how much she would miss it and what curse Grogar had put upon her.
She was also a former member of the Band of Misfits (wow did my style change .)
After Grogars banishment her voice did not return, and she was unable to find it, for he had used it in the creation of the sirens. She became distant to the world and vanished into the swamps and bogs of the at the eastern coast of the continent, between the sharp rocky mountains and the coast (which are now known as hayseed swamps). As the years went on she never showed any sign of aging, this was when she realized what Grogar what put upon her. She could walk the land for EVER! She would not die, she had to endure this torment for all eternity or until someone would end it for her, for she could not bring herself to do it. She was overwhelmed by grief and went insane. Her coat and mane had gone from her red and pastel colour to paleand dirty pink, if it was due to her Curse, the enviorment or maybe some sign of her aging showing through one does not know.
She not able to speak, began to lure wanderers into her bog with her looks attack them and drown them in hope, in ther struggle they would manage to put her out of her missery but all failed. In time she forgot her reason to kill and attacked without reason, killing everypony that dared to enter her realm, some say even eating her victims.
Until one day an old bearded unicorn mage and an old Batpony Lord, after decades of listening to rumour and whispers, finally found her…
P.S. She has no cutie-mark because her talent was her singing and grogar took it from her with her voice. which was another blow to her psyche