I'm having one of those moments where I don't know what to comment on because everything is so pitch-perfect and compelling that if I were to start quoting things I like back to you, I might as well copy and paste the whole thing. Your prose style is a delight to read -- it's lyrical but still retains the grittiness of everyday life in Egypt. I love that Harefre and Severus live and breathe their culture, that even though they're still Harry and Snape, they're also their own persons living in long-ago Egypt.
I also liked how you weaved in magic throughout the story, something so familiar in the HP context and yet different, because it's a magic of a different culture and a different time.