
Hyundai really trying to pull the "I didn't cheat because we weren't together"-card when he clearly cheated and that's what caused their relationship to sour. Buddy you're not the victim, you totally cheated. I hate this dude, he's inconsiderate outing the person that was supposedly "special" to him to strangers in their industry/workplace, being selfish and trying to steal credit for adding him to the movie, and now considering the MC doesn't want to see him again and has made that clear after not attending their group reunions, Hyundai keeps trying to push his boundaries and insert himself into MC's life when he is clearly not wanted

She's literally seeing memories, visual evidence of Osiris' plans to manipulate and brainwash Seth and the chaos he caused and his betrayal and still tries to blame everyone other than Osiris, like girl, you're not just hearing word of mouth, you're seeing facts

Well, she's never trusted Sekhmet and this is Sekhmet showing this stuff to her, so it'd be out of character for Isis to readily believe her 100% (while I LOVE Sekhmet, we have to admit she's still a nasty manipulative b... Look at how shemade Horus SA Seth, for effing sake. I LOVE her, but I still reckon she's one nasty law enforcer, our Lion lady)

Nope, no novel. This is an original webtoon.
And of course Ra already knows everything... But even if she had told them, none of Osiris' siblings would have ever believed her, because they had always considered Ra their enemy (ever since they found out Ra had tried to prevent their births, due to a prophecy that had once foretold that the children born from Nut, their mother, would screw Egypt over...)
The power Osiris took from Nepththys were Nephthys ovums: he wanted to put those ovums inside Seth and fertilize them with his own seed by having (forced) sex with Seth, thus forcing Seth to be the surrogate mother and carry the resulting baby to term.
I tried searching by the manhwa's name but found nothing
as far as i know it's an original manhwa