What if Nak Su and Mu Deok were originally one soul?

There was probably a time wherein a little child was used as an experiment. Or maybe there was a prophecy of a child who'll be very powerful and thus they had to split her soul.

Regardless if it was intentional or not, this little child had her soul split.

First scenario: The other half entered into a new body and grew up to be Nak Su. While the original body, as a side-effect, grew up blind.

Second scenario: The other half entered into a new body -- the blind body of Mu Deok. While the original body was adopted and grew up as Nak Su.

If this child is the missing eldest daughter of the Jin leader …

In the 1st scenario: the original body was adopted to some random family. Then when Nak Su bumped ("connected") to Mu Deok in episode 1, it re-connected them so when she used alchemy of souls, Mu Deok absorbed Nak Su because they recognized each other -- they were one and the same.

In the 2nd scenario: the body of "Nak Su" is the original body. When she was absorbed by her other half into Mu Deok's body, it probably led to the following:

* Instead of a blue mark, she got two blue eyes = 2 separate incomplete souls finally reunited and still trying to find common ground (they've been separated for all their life after all)
* In episode 6, her blue eyes started to dissipate = the 2 souls are finally getting whole
* Probably why the Jin family, especially the mother (take note: mother) did not recognize her own daughter, because they're in a different body.
* Possibly why the dog is seeing her simply as a soul shifter because the Nak Su and Mu Deok souls are, well, soul shifters. Even if they full become whole again, it still is not their original body.

Naksu is a small girl in the mage society who lost her family.

Now looking into the Jins family, the eldest daughter is lost

Imagine, if there was someone who performed alchemy of souls on Jins daughter at a very young age which separates her soul and body.

The soul was hidden away for some reason into younger Naksu before Naksu lost her family.

And the body of Jins daughter i.e body of Mudeok became blind and useless due to some mistake while performing alchemy of souls spell, that's why Mudeok was abandoned somewhere without the knowledge of the Jins who still believe she is alive and away somewhere

Mudeoks body welcomes Naksu's soul because it the very own Jins daughter i.e Mudeoks soul

Ohhhhh!! I thought that too

@Izyda

Oh My God! You have figured it out! ????

Well done! Jin Mu also is very much involved and it all started becoz of his broken Alchemy of Souls spell, and he's trying to hunt down Naksu so he can replace the missing Jin daughter or kill her to hide his act!

@Vniverse                                                                                                                                                                                                                                  Thank you :) Hope this could be a probable scenario. We'll probably find out this week or next, as everyone will know that Naksu resides in the body of Mu Deok. But they will not kill her, because she will be recognized probably by her mother ;)