Eunice and Khasius

Every fifty years my Nereid family has to sacrifice a princess to Lamia, the child-eating demon. However, the princess has to be nineteen years old at the time of her sacrifice. No one knows why Lamia wants a teenager if she only eats small children. The way the princess is chosen is by electing the girl who is going to be the right age one or two months before the first day of winter. My family made a horrible pact with Lamia many centuries ago to stop her from eating their children. When the time comes for the sacrifice, the chosen Nereid is taken inside a cave named 'Hells Mouth'. *This story is for young adults*