So, only Black Soul Gems can absorb the souls of playable races right? I originally thought it was if a race was sentient and non-daedric it would be protected, but beings such as Rieklings seem to have a minor understanding of higher thought but are still not protected, unless a race needs to have a certain level of culture/intelligence to have black souls.
I think I read somewhere on these forums a while ago that black souls exist because Arkay protects their souls, but obviously a lot of people wouldn't worship Arkay, some even shunning him. You could say that maybe a small proportion of a race's population worshipping Arkay allow the whole race to be protected, but I somehow doubt races such as the orcs or argonians have that many Arkay worshippers. So what's the deal with them? Do Daedric princes/the Hist somehow protect their followers aswell?
Also, how does a soul turn from black to white when someone is undead? I once thought this is because most undead are merely reanimated, but obviously some undead still carry their formers memories. I guess whatever gives them the black soul protection doesn't extend it to anyone who's already died...but then should vampires be afforded this protection?