You were a human that worked with the gods, you were a good assistant and Zeus even thought of making you a god. You had a secret bond with killer whales, there was always a pod near the shore and you had a strong bond with them. When they found out some were just happy and impressed but Ares was jealous and hated you

Ares killed you by tying a rope with bricks around your ankle when he tackles you on the pier and threw you in the water, you drowned in the killer whale pod, the killer whales were so sad and depressed they drowned right after you for you

You refused to enter heaven, never wanting to see the gods again, you stayed in hell, Zeus already send the god acceptence to you before you drowned so now you are the god of killer whales, the souls of the pods always float near you, everyone fears and admires you