"This is a good question. Unfortunately, only that Creator knows what kind of race He created.
The Firstborn Sons had been active in the Material World since the beginning of the Mythical Epoch. Once the fragile mortal races had adapted to this world, they each departed. Some returned to the Land of Origin, some answered the summons of the Ancient Gods and took on other duties, while others went to the Outer Planes to transform spaces unsuitable for fragile flesh to survive in.
By the middle of the First Epoch, even the people of that time regarded the 'Firstborn Sons' merely as beings from mythical legends. They had forgotten how their ancestors had taken root with the help of the Creator's children.
But even the most glorious age would eventually come to an end. From the end of the First Epoch to the beginning of the Second Epoch, the thirteen Ancient Ones departed one after another, accompanied by some Old Gods and Angels. The Firstborn Sons possessed status and rank no less than most Angels. Some left, some died, and some went mad."
The beautiful face in the water wore an expression of wistfulness. Shade asked again:
"Why did they go mad? Was it simply because the Ancient Gods left, and they could not accept that fact?"
The woman's head smiled:
"Perhaps. Perhaps not. No one can get answers from a madman. I only know that those Mad Firstborn Sons are all within the Sea of Origin. They—no, not they. It. They are waiting for 'Father' to return, until The End of the World. You dreamed of the Sea of Origin. What you saw was them."
"There is more than one?"
"Of course there is more than one. As for the exact number, that has no meaning. The Sea of