PhantomzK

This is for sure the case. In fact Im thinking that it might even be the same evil spirit that killed the first team member in the first episode. From what it looks like the host is part of a gang so So Mun's parents might have been his first kill. Since it was 7 years ago and he looks like hes in his 20s he might have killed them when he was around 18.

I'd say that its because he is actively involved in the different timelines.

What are the odds that the 'stalker' is actually the old man? After all if he is behind the MC's age reversion whats to say that he himself can't switch back between old and young?

So there are a few points that are unsolved that imo will lead back to the father of the girl in one way or another. His appearance in recent episodes leads me to believe that he will be the final villain after all. At the opening of episode 1, something that always confused me was how the MC's body ended up on top of what looked like a trash heap or dump site of some sort. However in episode 7, the killer goes to a grave looking for a body which he finds is gone. I am presuming that the body is that of the MC's.

*Note: I have yet to watch episode 8 as I write this so I may be unaware of certain details.

I am inclined to believe that the kidnapping of the girl is related to the father as it does not seem that she was killed on purpose. My question now is more towards how the MC ended up where he was in the opening of the series and who dug his body out in the first place. Did someone actually witness his murder, dug out his body, experimented on it, decided the experiment failed and thus threw his body away in a dump? If so how would that person be related to the girl's father?

Another possibility is that the so called 'santa klaus' killer is someone working for the father to abduct 'test subjects'. It might even be more than one person for all we know. If we were to assume that the 'santa klaus' killer had similar MO's on his file, this could be somewhat explained through the idea that all victims underwent the same or similar tests and as such had similar wound marks, etc. This idea would mean that there is really only 1 overarching antagonist in the show rather than 2, the father and his company.

I don't think the father killed his own daughter. I do think that there is a murderer out there that may or may not be connected to the father in some way shape or form but as I said we still don't know much about him. From what we are shown so far, he is seemingly depicted as a serial killer, but that might not even be the case since we are really only shown one killing of his (the daughter). But lets say that the father did kill the daughter. One logical way of thinking is that the daughter isn't biological. We aren't shown or told how the daughter died so she may have been adopted to be used as a test subject of some sort and died as a result. The so called 'witness' has also been rather suspicious. He seems to know that the MC isn't actually the detective. This means that he either knew the actual detective or knew the MC himself. Either he worked for the father or he is somehow related to the killer (probably not as an innocent witness). I am doubtful of his claims that he would be able to recognize the killer for sure as long as he saw his face again since they met when it was very dark and from what we are shown he at most could have gotten a glimpse of the 'killers' face. To me he is probably lying here. If we are to base this off of a realistic situation, he is unlikely to recognize the killer by face based off of their interaction.

As for the MC becoming human again....I am doubtful. He is after all technically dead. His wounds don't heal and as such any damaged organs aren't healing. If we were to pose that he does become human again, he will face several problems that will lead him to a permanent death. Two of which are:
1. Lack of blood - He has no blood running through his body, if he were to become human again, he would not have enough time for his heart to restart the blood pumping enough for a human to live.
2. Wounds - He literally has 2 open holes in his body that I surmise have punctured at least 1 organ (Don't remember the specific area). The wounds have stayed and hasn't healed since his cells are no longer alive to actively heal him. But since he is still functioning somehow without decaying this point is a little iffy. But the point here is that even if he becomes human, his wounds will not be able to heal in time for him to function as a human (logically).

My theory is that the MC was some sort of undercover agent probably working for the government or whatever. This would explain his advanced skills in 'killing' if you will more than a simple bodyguard. I think that he was put undercover for the father of the little girl to uncover some underlying illegal secrets that were probably along the lines of inhumane. He probably became close to the little girl during his mission and probably did work as a bodyguard for her under the fathers orders. However, he probably discovered some huge secrets that ended up with him being executed by the fathers people. My guess is that whatever secret that the father is hiding is also what resulted in him becoming a zombie as they probably disposed of his body with whatever chemicals, etc that may or may not be byproducts of said secret. This would mean that there are essentially 2 villains in the show with the father and his company ending up being the overarching evil by the end. So far the story is focused on the "santa klaus" killer but truthfully we still don't know much about him. But I think that as that story unfolds it will lead onto a bigger conspiracy in which the girls father is behind.

If we were to assume that there are 2 souls sharing the same body the more likely assumption would be that Mo Wan's soul is dormant. Remember back to right after the transference, the body is clearly controlled by a confused Mo Xin who apologized to her own body having assuming that Mo Wan was trapped in it. This is before any amnesia mind you. If we assume that Mo Xin in this scenario was mistaken and Mo Wan had not transferred to Mo Xin's body then it still shows that Mo Xin is clearly the one in control or at least the dominant soul. My best guess is that Mo Xin's soul is directly connected to that glowing tattoo mark that her friend gave her and as long as that remains on Mo Wan's body, Mo Xin will be in control. I haven't watched up to the latest episode yet so these are all my assumptions as well. However if we were to assume that Mo Xin somehow does have Mo Wan's memories it is possible that this is one of two cases: The souls are somehow fusing together into one identity (I don't really think this is the case) or that Mo Wan is slowly awakening as the tattoo slowly begins to lose function (in which case eventually Mo Xin would most likely die). Because we don't know how two souls in one body influence one another it is hard to say who is the one that loves the MC since it is possible that the dormant soul influences the dominant one in some ways (though this would make more sense in the scenario where the 2 souls were fusing). I personally think that it is Mo Xin who likes the ML. She fell in love with the person who saved her in the past. That is why she mistakenly fell in love with the emperor initially (she thought it was him who saved her). If we were to assume that her feelings became a blank slate after her amnesia, then it makes sense for her to fall in love with the ML since he was not only the first person she became close with but also saved her life. Also from her interactions with her family members, I believe that Mo Wan is more introverted in nature than Mo Xin which is not reflected by the rather childish and optimistic character of the FL. The difference in the original Mo Xin's personality and the current FL can be explained by several factors. In some flashbacks of Mo Xin, it is clear that she has always been rather upbeat and optimistic. This point is still reflected in the current FL in Mo Wan's body. What we haven't really seen yet is her level of childishness since we haven't had much interactive scenes of her younger days prior to her marriage to the emperor. Her marriage to the emperor might not have changed her core personality, but it necessitates a growth in maturity. Firstly she is now older, secondly she is becoming a mother, thirdly she is the empress, and fourthly there is danger from all sides within the palace that necessitates maturity. Thus the now amnesiac version of her is most likely her before all of those influences she had on herself after her marriage (Not to mention that she is physically in a younger body and so the younger brain might have some influences on her state of mind though I doubt the writers actually thought that deep). Someone mentioned her being awkward in bed with the emperor. This can be explained by the fact that she not just does not like him but hates him to the core, considering that the only reason she married him was to exact revenge upon him.