Board Thread:Dark Souls/@comment-88.109.169.234-20160719182505/@comment-4511886-20160719212945

You seem very confused about who Quelaag is. Quelaag was a Daughter of Chaos, which is very different from the Witch of Izalith.

The Lord Soul of the Witch is generally considered the soul of life. However, I don't think there's an official statement saying so, it's just gap-filling done by fans because of the correlation of the other souls. But yes, technically the soul of life would be the soul of souls.

Personally, I think the soul of life is more about manipulating the common soul shared by most, if not all, creatures. Points to support this include the fact that fire sorceries were used, seemingly, before Seath created "soul" sorceries. Additionally, Carmina's pyromancies "actualize the inner self", and they basically put certain bodily functions, such as sweating or adrenaline, into overdrive. Finally, the Bed of Chaos, and in fact all demons, are perverse creations of the soul's power being misused.

TL;DR: Quelaag is not the Witch of Izalith, and her soul is more likely to have the power of manipulating souls and, by extension, life rather than actually being the soul that creates life.