It's...It's Jeremy...not an ALT. Timeline or AU, he is part Siren and part Ent along with other humanoid species, I would watch yourself when he is in this form cause he has a bad habit of drowning people, he also can create water jets like a certain fish and likes to shoot things out of the sky...

He also hates dolphins and tries to murder them, the dark colors are cause he is mostly supposed to be in the deep sea, things are in his head beside his horns are like whiskers and can help sense things