Boy, I haven't made a Kahmunrah related post in awhile. Too long awhile, but here it goes.
I made a post regarding this years ago, for a different NATM fandom generation, but here we are.
In regards to Merenkahre's comment, "From the moment you were born...You were instantly the most precious thing to me." Ahkmenrah's face is not an expression of gratefulness, embarrassment or mutual fondness. That's a look of shock. Ahk knows what his father is saying.
On Merenkahre's side, when he says the line, he pauses and his voice changes. He is purposefully denying his first born son Kah and it pains him. They did this on purpose. It wasn't to "erase Kah" from the franchise, but rather a nod to how the family must feel about him.
As a Pharaoh, Mer knew what was right for Eygpt. Kah was cruel, murderous as his younger son was patient, kind (being son of Mer's main queen probably helped). Something could have happened between the two for Merenkahre to take away Kah's birthright, a final catalyst if you will aside from Kahmunrah's obviously wicked traits. Then for the youngest to have canonically been brutally stabbed to death (74 times) by the eldest, damn.
I'm just saying if my eldest son was a cold blooded murder hell bent on the constant need to fight and kill for total world domination, I'd be scared and ashamed and turn to the gentility of the youngest, too. I love Kah, but I definitely see why Merenkahre said what he did, as harsh as it may be.