@khjfan01 for now, with a little information we have after 2 episodes, I guess anything is possible hahaha
AS for the father not really being a killer because he's intention wasn't to kill a leaving person, and it was just a webtoon. Just an outlet for his creative mind: doesn't changed the fact that he is the reason Kang Chul's family is dead and I'm not sure for Kang Chul his intention would matter. It wouldn't for me. I don't think the initial intention ever matter for the victim tbh. I'm not painting Sung Moo as a villain of choice, but of a coincidence. The story he wrote, the characters he wrote happen to gain their own life. By a coincidence the 'just a plot device' that was murder of Kang Chul's familly happen to be something more. To justify Sung Moo calling Kang Chul a monster, the writers need to either turn the main character into monster (which I doubt will happen) or go with the he calls him a monster not because of his bad nature, but because of the fact he is unnatural, he should never happen, he should not be alive for the fact that he is just character in webtoon. 
Honestly, I change my mind every 3 seconds. There is too many possibilities... WE NEED TO WAIT BUT WAITING IS SO HARD.
Fcuk me, who is bothered to read all of that ROFLMAO
Lmaooo @Martin! U should read it cuz these theories are interesting!! 

@Kate I think I'm understanding more of where ur coming from. If I was Kang Chul how would I even feel to find out tht I was fictional, better yet to find out tht my universe doesn't really exist. I don't know if I'd care very much if the father was just the author n didn't have bad intentions. But as a viewer, I don't see Sung Moo as a villain at all. I think this is just a serious case of everyone misunderstanding everyone's intentions. 

I'm still on my "there's another Kang Chul" high. I think tht will justify Sung Moo calling Kang Chul a monster, but yes, we must wait to find out how it will all unfold. Gosh I can't wait for Wednesday!
I've got 4 theories as to who it could be......

1) The guy he beat at the Olympics (less likely because that's too extreme)

2) The prosecutor who wanted to give him the death penalty ( also likely but I think a little less)

3) Her dad (obviously! but remember this is a K-drama so things won't be so cut and dry!)

4) Someone else in the story (the real killer whom her father had created but took on a life of his own). Look at it this way, if she can go in how do we know someone else can't come out??? Maybe the real killer figured out he could leave and threatened her dad into killing Kang Chul (changing the story from what he intended in the beginning) and threatened to kill everyone he cares about which caused her dad to resent the whole thing in the 1st place (which is why I think he bitches about it so much). I obviously think this one is more likely lol

What do y'all think?
@Svetlana I LIKE THE LAST ONE! The idea that the killer threatened  Sung Moo with 'either you kill Kang Chul or I'll come out and ruin your life/kill you or someone from your family'. The only thing that kind of does not fit is the whole 'calling Kang Chul' monster. He doesn't really say he hate the world he created or anything like that, he is convinced that KC is the bad guy. + the painting of Cronus in Sung Moo's room (don't know how good is your mythology knowledge: he ate his kids coz he was cursed with the 'one of your kids will dethrone the same way you did to me by Uranus aka his father) suggest that he is strictly afraid of KC and losing the power of his own creation that's they the words 'I'll eat him before he eats me' aka I'll destroy KC before he gain enough power to go after me. I don't know, but I feel like this proves my theory that Sung Moo wants to kill KC because Kang Chul want to get revenged on the killer of his family, the at the end of the day it was Sung Moo's decision to kill them. 
Hmm, the dad doesn't necessarily seem evil to me even though it's quite plausible that he's the killer. He keeps repeating that he's 'justified' in killing Kang Chul. He seemed to have some guilt???? when his daughter accused him of murder because he kinda paused and then gave his excuse later-that it's okay if the creator kills his own creature. Ah, I don't know. It could literally be anyone at this point because we're not even halfway through the show.
I actually think that the father being the killer would be a little too obvious. I think we will actually be surprised when the killer is revealed and I would not be surprised if it was the father. I personally think there is someone behind the father that he is trying to protect his daughter from and so he is being forced to kill off his character for the benefit of his daughter.
Kang Chul family members were all shot right in the head, between the eyes. It's too precise to be the father's work. It's way too professional.
I think the killer could be :
- a korean should-have-been representative at the Olympic Games who did not accept Kang Chul retirement.
- a crazy fan girl who heard about him not being on good terms with his father (and by extension his family). Then, she might get jealous and try to harm Oh Yeon Joo. She happens to be on close term with the prosecutor or even be his daughter ! And since she is a fan, she could have joined a gun training center beforehand.
- a crazy fan boy of the Olympic Games finalist who lost against Kang Chul and trained himself with a gun jus so he could take his revenge. This boy just happened to be the prosecutor's son !
- Kang Chul himself ! I know, you don't want that to happen. (Me neither.) But just imagine that he has some kind of Dr Jekill and Mr Hyde personality, it would be a disaster if he manages to get out of the manwha.
The question is: how did the killer get Kang Chul's gun? Most sports props like that are being locked, so not everyone can just go and take it. It would suggest it must be someone somehow related to the whole shooting competition, like a stuff member or other trainee... It would be hard to stole a 'normal' (not harmful) sport equipment used by Olympic gold medalist, not to mention a freaking gun... It couldn't just be anyone. 
Tho I think it might have been someone related to prosecutor but NOT prosecutor himself. Coz he had no reason to kill Kang Chul's family at 1st place. Yes, he wanted to use the murder and 'frame' KC to gain recognition BUT I doubt he would go as far as committing a crime himself... it's way too dangerous and he would not risk his already blooming career. 
I don't think so its the father who is trying to kill him in the webtoon. There is something else to it just as why Yeon Joo is the only one to actually go into the webtoon world? I think its too early to guess!  
@KangHae It is too early to guess but that's what makes it fun! I just hope the show doesn't lose momentum tho.
@Svetlana i like ur last theory! Perhaps the real killer is threatening the father. But then why would the killer even need the father's help to kill Kang Chul?

The more I hear everyone's theories, the more I think it's another version of Kang Chul. I mean, the killer was able to get the gun which would be easy for Kang Chul to get, Kang Chul's fingerprints were all over the gun, the family didn't scream out when they saw the killer. 

Can't wait for tonight!
I really hope it's not another ver of Kang Chul tho, coz it would be so hard to explain it logically in those 16 eps without it sounding out f place. And honestly the fingerprints are not really a clue since it was his gun he used on Olympics so it's given there will be his fingerprints all over it. And the killer (as far as I remember) had a gloves on, so no fingerprints from him. + what would be the point for Kang Chul to put on gloves just for the murder without cleaning his fingerprints from the time he used the gun earlier? And even IF he cleaned all the fingerprints from the gun, it's still gun used on Olympics so it must be registered somewhere so police would know it's his gun anyway. For such a well planned murder such a big mistake he did with the gun would be ridiculous. Why would a different ver. of Kang Chul killed his own family and put a blame on himself for it? 
Im more curious as to who or what it is that's writing the story.
Maybe it has something to do with the killing. We don't really know how long it's been going on that part of the story gets written by someone/something unknown.
I have no idea what his motive would be. If these writers are good enough, I'm sure they could explain it logically in 16 eps. Kdramas, for the most part, aren't very logical to begin with. But i thought the same thing as well, fingerprints aren't a real clue because Kang Chul's fingerprints would already be on it to begin with. Idk, but I think there's more than "fear of his own creation taking control" being the father's reason for calling Kang Chul a monster. I just don't get tht type of vibe from the father. I think something must've happened to make the father think Kang Chul is gonna come after him. I don't think the father would go to these extremes just on a hunch tht Kang Chul MIGHT do something to him because he killed his family. 

I really do like the theory about the father being worried tht the two universes would collide or intertwine or something. Thts makes more sense to me than the father fearing Kang Chul will come after him because he killed his family. 

At this point in the story, another version of Kang Chul may not make much sense, but theres still 14 more episodes to go, anything can happen. All I'm saying is don't rule out another Kang Chul.