Achaius, Father of Sharks.
He’s a type of Daeva who has managed to survive the many long millenia by being a resident of the deepest oceans and rarely appearing to others. From him (and Orka, Mother of Whales) came the weresharks and the merkin, and he is regarded as a deity among the former.

He traps others in the huge exterior mouth, where his interior form can tear them up into smaller pieces and eat them at his leisure…. or have a conversation with them, depending on context. He must continue to swim or he’ll run out of breath, but he’s so large that few can keep up with him long enough to chat unless they’re in his mouth, so it’s a matter of convenience.

He also has two sets of sex organs- the larger set on his exterior form, and a smaller duplicate set on his mouth form.

Others may refer to him as leviathan or megalodon if they’re unaware of his true being.