*Spoilers* Han Seo Jun and Ji-Eun had...

One child together.  Ji -Eun had a second son with a later husband. Jung Ba Reum and Sung Yo Han are half-brothers, but only Jung Ba Reum is a killer. Yo Han tried to stop Ba Reum from killing but was shot by Ko Mi Choo and then killed by Oh Bong who thought she was getting revenge for her murdered grandmother. This is why Ji Eun looks terrified when she sees Jung Ba Reum outside of the hospital. This is why Han Seo Jun tells Ba Reum that he hopes You Han doesn't take over his brain because he wants his son Ba Reum to continue to be like him and continue to be this brilliant serial killer that no one can catch. Ba Reum has been either unaware of his killing due to having a fractured psyche or he's so psychopathic it just doesn't faze him.  Killing is just a normal part of life. Yo han is the boy who found Ba Reum in the field with the animal he was mutilating. He tried to heal Ba Reum's hand because he is a natural healer. His basement photos are from him studying the crimes and trying to solve them. He is also watching Ba Reum as he suspects him of being the serial killer (the adult Yo Han doesn't find out that Ba Reum is his brother until he gets the genealogy test). Ba Reum doesn't chase Yo Han for killing Oh Bong's grandmother. Ba Reum chases Yo Han because Yo Han came upon him while Ba Reum was killing Oh Bong's grandmother.  Ba Reum is aware of his murderous actions now because he has a part of Yo Han's brain. Yo Han's brain is making Ba Reum remember what he did and what he is. Since Han Seo Jun is a true psychopath he only cares about his offspring in a superficial way. Ba Reum is his latest experiment. He knows what happened when he implanted a violent mouse's brain inside a docile mouse's brain, but what happens when you place a non-violent--even genius--brain portion inside a serial killer's brain? Will Ko Moo Chi be able to kill his friend when he realizes what he is?  Will he blame Ba Reum's behavior on what was done to him or will he see that Ba Reum (according to the show) had a 99% chance of being a killer from the womb and had no more control over what he was than we have over skin color or height? And has anyone noticed how many people are murdering others in this show when they feel they have the right to? The difference between Ba Reum and the ones who kill for revenge in the show is that they kill for circumstance, Ba Reum was born feeling he had a right to kill. We are not all psychopathic killers, but we are all part of the human experiment. We are all capable of great evil. We are all mouse.

This story is written very tightly, so tightly, in fact, that I think it might be over a lot of people's heads and might lose some viewers that way. Lee Seung Gi's acting is amazing. I simply have no other word for it. People are asking how could Ba Reum be such a nice guy if he's the killer. If you read about serial killers you'll always read that he was a nice guy, stayed off to himself, usually friendly and helpful. Sometimes even charming. That isn't an act. That's just how serial killers who can fly under the radar are. 

I remember reading about one serial killer and he said that he didn't see killing people as an anomaly. He just felt it was something you were supposed to do like get a job or buy a car. Just a part of life. I think some might struggle with being a serial killer and may even turn to religion to try to squash the desires and fantasies down. The BTK killer and Jeffrey Dahmer come to mind. Eventually, however, the fantasies and desires become too much and they regress. Killing makes them feel alive, like falling in love makes most of us feel. Jeffrey Dahmer became baptized in prison and was having regular sessions with a pastor, but would form his mashed potatoes at dinner into little body parts and douse them with ketchup even when he knew he was making the other prisoners (killers themselves) uncomfortable. The fantasies and desires were simply too much for him.

I don't think Ba Reum has a fractured personality so that he is unaware of his killing. I think he has his killing self and killing memories safely compartmentalized. He has two faces like Ted Bundy, Dennis Rader and John Wayne Gacy. Ted Bundy served on a hotline for women's safety, John Wayne Gacy was a clown for children's charities. Dennis Rader was an executive officer for his church. It's just their two faces. When one comes on, the other goes off.  It's also telling that Ba Reum is a police officer, albeit a low ranking one, and that he tries to insert himself into the investigation. Serial Killers are often drawn to law enforcement. 

Ba Reum may appear to have an emotional attachment to Oh Bong, but he doesn't. Psychopaths don't form emotional attachments like that. They may feel a form of possessiveness over another person, but they are incapable of feeling actual love. They care about their children on in so much as their children are an extension and reflection of themselves. 

Dr. Daniel Lee is the odd element here. I still need to understand what was with his attack. Who attacked him and why? Why did he go undercover and why? Why does he want Ba Reum to be a serial killer that causes other killers to "cease from troubling"? Is he trying to play god but in a different way than Han Seo Jun? Does he really believe that Yo Han's brain portion is affecting Ba Reum (and how did he know about the surgery)? Does he really believe that Yo Han was the real killer? After all, he would have known which babies had the psychopath gene. I can't believe him being a scientist and not keeping track of what those babies did as they grew. Did Yo Han also have the gene but turned out to be the 1% who are geniuses? Or is Dr. Lee playing some strange game with Ba Reum and getting  his own chance to determine who lives and who dies? I expect there are answers forthcoming.

The use of orphans does bother me in this series. Choi Hong-ju is the daughter of a policeman in a high profile case but someone has to raise her? What happened to her? How did she just show up somewhere as a child and no one tried to find out who she is. I realize that another little girl's body was found with her clothes and her DNA on them, but no one did DNA on the bones? There were no dental records? Since when is identification done so haphazardly? That was a stretch. What happened to Jae Hoon after the murders of his stepfather and possibly at least one sibling? They just released him into the night? Was he placed in an orphanage? Serial killers can stop killing for a period of time, but it seems to me an orphanage would be a highly-charged environment for someone like Ba Reum. With Ba Reum, Ko Moo Chi, his brother, Oh Bong and Hong Ju we've got entirely too many orphans floating around for one series. This is a shortcoming in the writing for me. 

There seems to be some foreshadowing with Ko Moo Chi. He is a killer. Most children would have been terrified of the person who killed their parents but even as a child he goes after his parents' murderer (also, I didn't quite buy that a terrified young child would be able to clearly see the killer's face with a hood on at night through the crack in a suitcase on the floor, another bit of sloppy writing for me). Moo Chi threatens a rapist and murderer until he leaps to his death from a building's rooftop. I think he's too rash and hot-headed to be a serial killer, but he's a killer. Just a killer with a code.

I think all the actors brought their A-game to this production. I am especially impressed with Lee Seung Gi's acting and Lee Hee-Joon's performance when his brother was being murdered tore me to bits. There are parts of the story that could have been written better, but overall it is a tight production. I hope the series keeps up this degree of excellence to the very end and doesn't become sloppy. 

I agree with your description of moochi. I feel the series might end with him killing Bareum (no theories just a guess). He doesn't have the predisposition of a serial killer or a psychopath despite his trauma. but he still has enough anger and vengefulness to kill. 

I don't think Ba Reum's aunt is really his aunt. I think she is a plant the government (or perhaps Daniel Lee) put there to keep an eye on Ba Reum after  his surgery. 

I assume the three bodies were Jae Hoon's stepfather, his half-sister and it could possibly be his half-brother. Yo Han and Ba Reum could simply be childhood acquaintances. The little boy in the field did say that he liked to help his friends when he bandaged Ba Reum's hand. However, how did Ji Eun (Jae Hoon/Ba Reum's mother) wind up raising Yo Han if he were not her son? Did she adopt Yo Han?  Is Yo Han yet another orphan that someone other than his real parents took care of? I hope they will be able to give satisfactory answers to this. 

 somebodysbabygirl:

The use of orphans does bother me in this series. Choi Hong-ju is the daughter of a policeman in a high profile case but someone has to raise her? What happened to her? How did she just show up somewhere as a child and no one tried to find out who she is. I realize that another little girl's body was found with her clothes and her DNA on them, but no one did DNA on the bones? There were no dental records? Since when is identification done so haphazardly? That was a stretch. What happened to Jae Hoon after the murders of his stepfather and possibly at least one sibling? They just released him into the night? Was he placed in an orphanage? Serial killers can stop killing for a period of time, but it seems to me an orphanage would be a highly-charged environment for someone like Ba Reum. With Ba Reum, Ko Moo Chi, his brother, Oh Bong and Hong Ju we've got entirely too many orphans floating around for one series. This is a shortcoming in the writing for me. 

To answer your question. Choi Hong-ju was clearly kidnapped by the headhunter. I don't know if she managed to run away or she was left alone in Han Seo-jun's lab after he got arrested. But I guess that once she was free,  not going back to her parents was her choice. Maybe she felt she couldn't go back to them after she was forced to become Han Seo-un's unwilling assistant. She probably showed up in some orphanotrophy saying she couldn't remember her name and that was that. 

About DNA testing and dental records. Dental records are not forensic evidence used in every country. They are quite popular in USA, but in my country, for example, dentists don't keep records of patients' teeth.  About the identification done so haphazardly...ehm well we are talking about the police. There is a dedicated forum that deals with cases from all over the world that examine police's investigation done wrong, from the disastrous investigation of the murder of JonBenet Ramsey, to the more even disastrous investigation of the murder of Meredith Keercher. So far, I don't consider anything thing that I have seen in this drama a stretch, apart from Daniel Lee's resurrection. 

We still don't have any info after the psycho kid leaves the police station. Maybe, he went back home?  What it is interesting to notice is the words used by the policeman when he was talking to Daniel Lee. He said, "There's no way. An 11-year-old couldn't have murdered a whole family".  Ideally, he should have said: "There's no way. An 11-year old couldn't have murdered his whole family".  However, apart from saying this, I still don't know if it just a translating issue, or something completely irrelevant to the story

 somebodysbabygirl:

Jae Hoon went back home to a crime scene? Without a legal guardian? That makes no sense. He was just found in a home where people had been brutally murdered. If they felt he didn't commit the murders they would have at least expected him to be severely traumatized. We see him walking alone in the police parking lot at night after being questioned. No parent, no guardian, no nothing. What police department does that? 

I hope they will explain this. Probably they will add some more scenes when Jae Hoon (JBR) will start remembering his past. 

 somebodysbabygirl:

hey could have gotten DNA smeared on the clothes of the body found then they could have gotten DNA from the bones, hair, marrow, something.

Maybe you don't remember, but they did test the hair found on the girl's hairband. But the policeman with the psycho kid tampered with evidence. The police found the body with the same clothes as Choi Hong-ju when she was kidnapped. They tested the hair found on the hairband and it matched the DNA of Choi Hong-ju, or her mother/father.  

They tested the hair found on the hairband and it matched the DNA of Choi Hong-ju, or her mother/father.  

 The bones. The bones. The bones. Why test hair from a headband when you have the bones right there? Hair can always be transplants from somewhere else. It could have been transplanted evidence from another victim or even from the killer. That's like having a McDonald's hamburger on your  plate but looking at the wrapper it came in to determine that it is a hamburger and not a Filet-O-Fish sandwich. When you have the most decisive evidence in front of you you address that evidence. I know the screenwriter had to come up with a way to explain Hong-ju, but this scenario was sorely lacking. 

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If it had not been such a high profile case (two children of a police detective kidnapped, one hit by a car when he managed to get away) then I might could accept such sloppy identification of the remains. However, cops tend to take care of their own. The DNA of the bones would have been analyzed in real life.  Having only the hair analyzed is too convenient and a weak attempt to justify Hong-ju's survival. And this still doesn't address how Hong-Ju got to be an adult (a college-educated one at that). Was she raised in an orphanage that made no attempt to find out who she was? That is also a logic longshot if that is what the screenwriter did. Did some family take her in and pretend she was their daughter? That may would work. I'm not sure what the laws are in South Korea are for documentation for children, enrolling them in school, etc.