(FINAL update) How can NakYeon survive?

As of episode 7, I don't trust Bu Yeon.

Is she selfish? Or, was she was corrupted by the Ice Stone?

If Master Lee's revelation in Episode 7 is any hint, Bu Yeon planned to consume Nak Su's energy since Part 1. But she had to retrieve the Ice Stone first from Jin Mu.

It is a huge gamble. But, as per Master Lee, everything is still going to according to Bu Yeon's plans.

Bu Yeon taught Nak Su about the Ice Stone, and manipulatively led her to make choices Bu Yeon wants without Nak Su being the wiser. She wants Jang Uk, the true heir, to have the Ice Stone and to keep Nak Su from using it herself.

Once that was done, Bu Yeon will unleash all her raw energy and Divine Power to consume Nak Su. Unfortunately, Jin Mama almost killed Bu Yeon, then Jin Mu made Nak Su go wild which further weakened Bu Yeon.

Now, in Part 2, with a weakened Bu Yeon, Master Lee almost removed her soul. But in the end, Master Lee did not.

Quite possibly, Bu Yeon talked to Master Lee and coerced him to do her bidding. Master Lee helped Bu Yeon sealed Nak Su's soul, so Master Lee can redirect Nak Su's energy to as a source for the Body's Divine Power -- ssince Bu Yeon can not provide the energy.

But in the process, Bu Yeon is slowly consuming Nak Su's energy too. Once Nak Su is depleted, she will disappear, and Bu Yeon will re-emerge.

Unfortunately, for that to work, NakYeon (the new identity) must not use the Divine Power. Because everytime she uses it, the seal on Nak Su's soul weakens, thus Nak Su's memories are leaking.

If Nak Su's smemories are leaking, Nak Su's soul will notice her energy is being consumed by Bu Yeon.

And well, with a weakened Bu Yeon and enraged Nak Su, they will definitely die.

Everything lies on NakYeon, the new identity, to control those two souls, possibly merge those two souls. Bu Yeon and Nak Su definitely want to live, but them occupying one body would no longer work.

Nak Su is under the control of Jin Mu. A repeat of Part 1 is possible if Jin Mu discovers Nak Su is back, if one of the souls are stronger, the other can not do much about it.

Then there is Jin Mama who definitely wants Bu Yeon to be back.

NakYeon is their only hope.

IM YourOnlyOne

Thanks for your analysis and your effort and for sharing it with us.

This will definitely help all Alchemists understand better.

 IM YourOnlyOne:

Maybe being inside the prison would give NakYeon the power to subdue the Ice Stone-touched Bu Yeon.

I am pretty confused with this sentence. 

Do you mean to say that NakYeon can subdue the Ice Stone?

And JBY's heart was touched by NakYeon's action?

I was thinking about why JBY took in Naksu's soul in S1. It must be just like how NakYeon is rn.

JBY couldn't remember who she was so she took Naksu to get her memory and divine power back.

But the plan was interrupted by her mother choking her. I think that was the time when she remembered everything too cos of the flashback scenes.

Also, I think NakYeon went to Jin Mu this time to do what JBY would do: protect Jinyowon instead of her revenge. She will revenge Jin Mu for sure but now is not the time yet. And JBY will take revenge for her if NakYeon failed to do so.

Apparently So-i is not a viable choice of body? As you need to be at the brink of death, not dead.

@IM YourOnlyOne thank you for your in-depth analysis. on this. 

Ok I have a question. Let's say that Naksu's soul gets out of the body, what will JBY look like? As of now she looks like how Naksu would. Would she stay the same or will she turn back to how Mudeok looked like cause I thought that Jung So-Min will not be in this season.

I think, there is a possibility for a happy ending for all -  Bu Yeon will reborn as a child of Nak Su and Jan Uk. I thought about that possibility when her mother wanted to force her to give birth to a heir of Jin family.

It seems like the divine soul in JBY is is the original Jin priestess Jin Seol-ran, who may have entered Mama Jin's stillborn child through the ice stone (where she preserved her soul). In that case, it could well be JSR, not Naksu, who leaves JBY's body once all the dust has settled, having achieved her goals.

And Master Lee is talking complete bullshit as usual.

FINAL update

Changelog:

Updates

• Episode 9 and 10
  • As was guessed in Part 1, Bu Yeon's soul is Jin Seol Ran.
    • The real soul of Bu Yeon never returned.
    • The soul that entered the baby was the soul of Jin Seol Ran.
  • As has been mentioned before, Part 1 is about and was planned by Bu Yeon.
    • Bu Yeon's objective was to retrieve the Ice Stone.
  • Part 2 revealed:
    • Bu Yeon (i.e. Seol Ran) attracted Nak Su (as was said before (even in Part 1)), Bu Yeon needs Nak Su for her plans).
    • Bu Yeon, in Part 1, taught Nak Su not only to lead her to make decisions favourable for her (Bu Yeon) plans, but also because Bu Yeon also planned to give control of the body to Nak Su.
    • Jang Uk was part of Bu Yeon's plan (as was mentioned before, too)
  • Master Lee is alive because he entered a dead body of a boy.
    • He practically hinted that if a soul enters a dead body, they would not suffer petrification, thus, they won't need to consume a living person's energy.

The situation

• Episode 9 and 10
  • Bu Yeon is actually Jin Seol Ran (I, and others,Se posited this back in Part 1)
  • Bu Yeon meant by making Nak Su disappear, only temporarily. Bu Yeon never intended for Nak Su to disappear permanently.

Episode 9 and 10 ending to the NakYeon dilemma

1. It was not clear if Bu Yeon (a.k.a. Jin Seol Ran) left the body, because in the last scene, both of her eyes glowed blue:
   • The mark of a soul shifter
   • The mark that there are two souls in the body
2. In the scene when Bu Yeon woke up the soul of Nak Su, they were in the same place when the souls of Bu Yeon and Nak Su first met in Part 1.
   • It's a depiction of the internal place within the body of the two souls.
   • Bu Yeon (a.k.a. Jin Seol Ran) is more likely still in the Body. Bu Yeon is simply sleeping.
     • This is similar in Part 1 when it was first revealed that Bu Yeon takes control of the Body when Nak Su is sleeping.
3. WIthout Bu Yeon, Nak Su will reject the Body and will petrify if she does not consume a living person's energy. The side effect of Alchemy of Soul (instead of using Hwansu).
   • Like in Part 1, it was Bu Yeon that kept the petrification at bay through the Divine Power
     
   • It was also showed in Part 1 that the Divine Power can purify the energy consumption process.
   • In Part 2, since Bu Yeon has regained her energy, the Divine Power can tap on Bu Yeon's energy instead of Nak Su's energy.
   • Once again, the Diving Power is at work putting the petrification at bay, just like in Part 1. The only difference is, there is no more need for Bu Yeon to wake up.
4. In the end, NakYeon, or as herself has chosen, Cho Yeong, survived.
   • She still is a new identity. If the English translations are correct, the way NakYeon/Cho Yeong speaks is still detached to her past identity as Nak Su.
   • And she also has full control of the Body's Divine Power.
     • Which Bu Yeon probably relegated control to NakYeon, since she decided to sleep.

Some other notes

• Jin Bu Yeon's baby body was already dead, Jin Seol Ran's transfer into that body was similar to Hwansu (like Master Lee), no side effect, even though the Ice Stone was used.
  • Even if there is a side effect (because of the Ice Stone), Jin Seol Ran's energy was very powerful, and the Divine Power in the Body was also powerful to push back the petrification (as we've seen in Part 1).

Memorable

1. Born as Cho Yeong
2. Grew up as Nak Su, the assassin
3. Lived as Mu Deok
4. Resurrected as Bu Yeon (Part 2 version of Bu Yeon, not 'Bu Yeon as Seol Ran') 
   
5. Reborn as Cho Yeong (a.k.a. the NakYeon identity)

NOTE: This is only how I understood and reconciled things from an in-universe perspective. It does not mean this is how you should interpret the show.