
Off the top of my head, pretty much all the male greek gods had at least one other man they had the hots for, including Zeus. But considering that when we're first introduced to mystery man, he's on a ship with very mermaid-esc looking people in the background and Isis made a deal with him in relation to flooding Egypt (? hope I remembered right), I wouldn't rule out Poseidon being a candidate either

I don't know much about history in comparison to mythology BUT the Egyptians and Greeks did have a shared God named Serapis (though idk too much about him, just that he exists, I know a little bit more about mythology in comparison to ancient history, but I'm not one of those mythology nerds).
Also, this manhwa isn't really sticking to original mythologies anyway, so it may not be sticking to history as well. And we know that genderbending gods isn't out of the question for Ennead, so although unlikely, goddesses are actually potential candidates for Mr. Mystery God as well.
You made a VERY interesting point though, I like it.

Considering the Bootleg Jesus was introduced as a god who was supposed to be an opposing opponent to Seth, I thought it was supposed to be a god of war from another culture. He also has rather arabic vibes and they call him 'hairy' so I don't think Greece/Rome fits. Mesopotamia on the other hand is a precursor for the Arabic culture and is a direct neighbor to Egypt if I remember correctly. That's why I've assumed the god would be someone like a Sumerian god of War or from the Mesopotamian culture like Ninurta or Nergal.
But mu knowledge of ancient cultures is very vague and I don't feel like spiraling down the research hole so I'll just wait for the comic to reveal who it actually is = u =
That foreign god looks so much like the translated Jesus of the West, and for the love of author-san pls pls don't be Jesus, but I legit gasp when I realized that he could also be Zeus, but then that means he went for a man and idk if he's into that or naah..??