
How much of this is consistent with the Egyptian myths?

All of the gods really do exist in Egyotian Mythology. The familial ties are also true. Osiris really was murdered by Seth (but only because he was jealous). Osiris truly did become the lord of the underworld and Isis did resurrect him and conceived Horus..the stone boat trial is also present in mythology and so is the whole "Seth went to Horus and tried to seduce him" thing (no rape though..I think)....overall, lots of this is based on true mythology and there are additions that the author made to add romance later on.

There are many interpretations, but one does say that Seth does sexually abuse Horus. But that just one version and interpretation. Though, the conflict of Horus and Seth is almost continuous. There a is also a story of a battle involving 'semen'.
Its a wierd story for sure, but interesting one. Seth and Horus trying to get the semen of the other. It is a way to weaken the other, as semen is seen as poisonous?
Anyway, Isis interfered to ensure only Horus semen got on Seth weakening him, as its poisonous? But in some other interpretations Seth was impregnated by Horus (≧∀≦).
I doubt the author will take this route, but it doesn't hurt to imagineヾ(☆▽☆)
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