
Thecla:
I actually don't understand the one soul theory (no doubt explained in much more detail elsewhere!). I
In simple terms, @DaisiesOh one-soul theory is:
1. +/- 20 years ago, Jin Mu took a 4-6 year old Cho Yeong to the mountains.
2. 10 years ago, Jin Mu soul swapped Bu-yeon into Cho-yeong's body and brainwashed her/changed her memories to become Naksu The Shadow Assasin. Cho-yeong' soul was swapped into the blind body of Bu-yeon and she eventually became Mu-deok.
3. When Naksu was wounded, she performed AoS and ended up swapping back into her original (Bu-yeon) body. Just like the Jang Gang/old King swap. Cho-yeong returned to her original body and died.
4. I'm not sure if DaisiesOh has theorized much further on the dynamic, but it helps me to think of it in terms of a "split personality". "Naksu" is dominant, Bu-yeon is suppressed, but her "divine" powers emerge in situations of life or death.
It's a very plausible theory. To me, it doesn't matter because in the end Jin Bu-yeon is in her body and her mission is to save Daeho and seal (or destroy) the ice stone.
Simple outcome:
One Soul Theory - the two personalities will eventually merge.
Two Soul Theory - One soul eventually swaps out of the body, leaving the other one in control (or dead).