Sooyi

Sort of unrelated to the plot but Kwon Hwa-woon has updated his Instagram stories hinting that he'll be in a sageuk, "his first since 'Six Flying Dragons'". It looks like he'll be joining the cast of "The River Where the Moon Rises" judging from the fact he's wearing a long red robe and a top knot with some of his hair down. The reason I'm talking about this is that maybe he won't be very present in the following events since Kwon Hwa-woon is entrusted a role in another drama (but then again, until now he had less scenes than Lee Heejoon, so it's still possible that he will be juggling two roles at once).

I was thinking that the killer left and somebody else was in the church, but then I remember when Bong-yi came, "I Am God" was not written on the wall. Every time I have a theory, there's one detail that doesn't back it up lol

Or maybe Yohan was checking Bareum's birthdate?

Yep and it goes well with the cliffhanger of each episode.

I used to think he was the Cross Killer but then after episode 6, I'm viewing things differently. If we consider that Jaehoon is the Cross Killer and we compare him to Yohan, Jaehoon was wary of people's conduct toward him, but he remained indifferent at the same time, not to mention he was feared by others, whereas Yohan was physically ostracized for being the Headhunter's son and he was angry at being treated so.
And Yohan acts cold and courteous to various people except for Hongjoo (it's interesting because it appears he's more open toward her only, showing fear and joy). Plus, now that I think about it, if he was keeping really compromising secrets, he wouldn't have let his mom or Hongjoo enter his house freely in the first place.

I feel like the Killer stalked the victims in person as well. How did he know that the single mother (Lust) worked as the kitchen help in a hostess bar and was being approached by clients? How did he know that the businessman (Greed) had fallen on hard times?

2. I wouldn't say that all the victims were "nice" but at the same time the Cross Killer chose people who would likely fail due to personal circumstances. For example, the woman who represented gluttony was bulimic, and I think the Cross Killer specifically approached her. However, I think Moowon was literally a paragon of virtue from what we've seen of him so far, which was why he couldn't pass the Cross Killer's test.

I'm having doubts again that Yohan is grown up Jaehoon after episode 6 because of some new revelations and the way the scenes in the drama are presented. But yeah I think the woman we see in the house is Jaehoon's biological mother and his father is his stepfather.

Speaking of Christianity, I could see Yohan and Bareum as Cain and Abel. Cain and Abel were the sons of Adam and Eve. The older son tended fields for a living while the younger son herded sheep. When it came for them to give the fruits of their labor to God as offerings, the latter accepted Abel's only. This made Cain mad, and he subsequently killed his brother.
Both of them were seemingly born with the psychopath gene, but one grew up shunned while the other accepted.

Jaehoon did kill his family because there's a flashback early in episode 6 following Moowon's death, and we see bloody Jaehoon at church, and he demanded God why He didn't listen to his prayer of not wanting to be a monster and said he's no God. He affirmed he's the new God and then vowed he will judge the people who listen to the former's "nonsense".

I was hesitating whether Han Seojun was referring to his sister Jennifer (then the question would be "have you found her killer?") or his brother we don't know of ("have you found your brother?"). Han Seojun used the term "dongsaeng" (younger sibling in Korean) so it is gender-neutral, but then again if he was referring to Jennifer, he would have directly said her name as Sung Jieun is aware of the tragedy that had happened.

I think Jaehoon's mother is his real mother because when his father called her to come home so that he can vent about him following the meeting with his teacher, he said "your" son in a rather pointed tone. We can guess that she might have asked which son had a problem at school.

Remember at the end of the first episode we see little Jaehoon put a mouse inside the snake case at the zoo expecting the former to get devoured by the latter, but the mouse seemed to defend itself quite well from the snake, but we didn't see the outcome of the confrontation (I think there was a scene transition just when the mouse jumped at the snake). So maybe Bareum is a "mouse" that is in equal footing with its predator.

Kwon Hwawoon is sure hot. And he can mark his presence next to Lee Heejoon and Lee Seunggi.

I feel like the first 6 episodes are the set-up to what caused the "big change" in Lee Seunggi's character and why he will officially join Moochi's team as it's hinted in the teaser for episode 7. So in other words, Lee Seunggi's character will likely take center stage from episode 7.

Unrelated but I chanced upon the Instagram account of Kwon Hwawoon who plays Sung Yohan and these pictures made me laugh so much :))) (it's a breather from the darkness offered by "Mouse"): https://www.instagram.com/p/CMEebGbA_RR/?igshid=19wtdfo255q8o

And I think a brain transplant is a bit too far-fetched even though the writer is known for her fantasy and sci-fi plots.

Hongju and Yohan are obviously in a close relationship from the way it's hinted they're intimate and she freely enters his house (quite a bold move for Yohan who has a secret study inside).

The writer reveals a lot but then it leads to so many speculations. I understand your pain XDDD

It wasn't shown??

I don't know but what I find it strange is that she said "I should have killed you back then". So she doesn't believe that Jaehoon killed his stepfather and siblings??

I think the swapping theory is still too early. Dr. David Lee was talking about a case of a serial killer who savagely killed his grandparents and he supposedly changed after he suffered a head injury.