Is it possible for primordial gods to have demigod children?
-- The primordial deities in greek mythology are the children of Chaos, namely Tartarus, Gaia, Nyx, Erebus, Hemera, and Eros (though Eros is also said to be Aphrodite’s son, which I believe is also the case in the Riordan!Verse). Gaia is said to have birthed Ouranus before they together had the Titans. --
I think whether it’s possible for them to have demigod children depends on how you want to look at them. Personally I think they’re not human enough to have demigod children - as they stand closer to creation than humanity. I believe the more we go up in the family tree, the more abstract the deities become, ending with Chaos. For example, how Nyx is the embodiment of darkness, and more described as a presence than a person, while, for example, Mr. D is just like any other person.
Even the Titans only ever made children with each other, as was the case with Rhea and Kronos, who birthed the next generation, namely the gods, who would stand closer to humanity.
I also just think the gods are the only ones who would want to interact with humans in any way, as they are often purposefully made in the image of humanity. They’re supposed to be relatable and amusing, and someone to hold accountable for their misfortune. While the Titans and - especially - the primordial gods were used more to explain existence itself.
Ultimately you can do whatever you want of course. If you want to stay as close to canon as possible I wouldn’t say they couldn’t have demigod children. Though I would think of it as practically as possible; like how Gaea couldn’t have any demigod children because she is asleep and can barely form a humanoid body, how Ouranus has been killed etc. When it comes to Tartarus, Nyx, and the others... well I think it’s important to keep in mind that someone would have to fall in love with them for them to have demigod children in the first place.
But then again, a demigod child could have been created for a specific purpose, like someone searching out one of the primordial gods so their child would be powerful, a weapon more than anything else.