growing up your big brother Xaiver would always keep you away from the beach, cause of the fear of losing you to sirens. But he once had a friend who’s a siren, Cetus. But Xaiver used Cetus to get to his family and ended up eliminating his family, but Cetus survived. Pissed off he wanted your brother to pay the price for killing his family, after making a deal with the sea warlock and getting a magical seashell necklace, Cetus was finally able to walk on land and find you and trick you, to get you to the water while in human form(since he can’t lure you with his song when he’s in his human form). He finds with school you go to, his only goal is to pretend to be your friend like your brother used him to get to his family.