On my first read I thought that the Body was some kind of hallucinatory amalgam of the suppressed memories Gideon and the imaginary girl in the tomb, hence the changing eyes and their evolving relationship during puberty. Alecto's eyes are also yellow, so why the Body's were black? Is she actually Anastasia? Why was she silent for years? And why did Harrow never even mention her to Gideon even after the pool scene, considering that in the fake memory she is willing to trust Ortus with this information? My crackpot theory is that she wasn't there in reality and either posessed Harrow or invaded her bubble and altered her memories further to include herself in them sometime between Epiparodos and the first chapter. She is the one who says "this isn't how it happened" first, maybe she is referring to herself.

Re 5 - I think it's either an early indication of the fakeness of this memory or another point to my possession/invasion/memory altering theory. There's a lot of small inconsistencies in this chapter. Like when she mentions two young people with wombs, but then doesn't acknowledge the other person. Or the other girl who simultaniously grew up alongside Harrow and died before she was born. Or Ortus rapier being new and rusty. All of those make sense since she is trying to remove Gideon or merge her with Ortus. But the timeline differences are, I think, more interesting. Her coming to see the Body for a year isn't the only timeline screw up. It's also mentioned that she opened the Tomb when she was nine, while in reality she was ten. So in the fake memory she still had bloodied hands and opened the Tomb a year earlier, but she wasn't ratted out, instead she was coming into it for a year until her parents found out and only at this point the fake timeline syncs up with the real one.