You were a just a young halfblood human, when Hera found out you were one of the kids born out of the many adulteeries of Zeus' (his husband).

The Godess condemned you to be looked under the sea, only allowing you to sing like a siren in the night of the 23th of June, as a way to be found and freed by a man that wasn't Zeus.

Ares, the god of war, was just walking around the coast after another one of his battles when the sad melody of a girl singing from inside a cave reached his ears.