Episode 6 was a bit confusing. And there are a lot of ideas I can come up with, but only one is quite reasonable for me.

Maybe, the man in black robes is from another dimension. And both Kang Chul's and Oh Yeon Joo's worlds are inside a webtoon.

Because there seems to be someone, who is invisible but knowledgeable, and controls both worlds.

What are your thoughts??

That would be mind-bending lol. This drama has the same feels as what I had when I watched "Inception". :)

I actually think there's another force at play too but I also think that the killer could also be a manifestation of SM's creation. The real monster he created was not KC but in fact the killer (who ended up having free will of its own too). Similar to how dad created KC to have such a strong will that he ended up defying his creator, the killer probably had such a strong desire to kill off KC's love ones (including attempting to kill him but not fatally wound) in order to drive the story forward. Killer is a glitch in the story - he has no identity/face, yet his purpose is to make the main character stronger. In order to do so, he's driven to kill off all of KC's love ones and attempt to kill him so that KC will have something/motivation to chase after. This is all to continue the story. I suspect that KC will have to get rid of killer in order to fully leave his fictional world. By that I mean for the manghwa to stop uploading his every move in both dimensions. The killer existing is probably the reason why KC will always be uploaded on a manghwa. So this explains episode 7's preview where the killer is now after YJ. Killer wants to kill YJ and KC wants to srop him...this will drive the story forward with YJ being in danger. I dunno, this drama is making my head think too much...!
a webtoon inside a webtoon: that is inception-esque mindfuckery. it's not outside the realm of possibility, but I don't think it's the case here since I haven't picked up on anything that hints toward it. I could have very well missed important details, but as of yet I haven't noticed indications that point toward yeon joo's world being controlled---or even locked in a battle of free-will/self-awareness vs creator's intent---in the way that w is.

more for it being faceless than any other reason, I believe the hooded figure is (or is akin to) a personified concept. whether I think it's self-realized or not, well, I don't really know what to think. so far I've been working under the assumption that it has no identity apart from the generalized but characterless villain that sung moo inserted as part of his set-up. I'm also guessing that, at some point, it came to represent the manifestation of sung moo's animosity toward kang chul. but what allows this thing to jump worlds, & why didn't it freeze with everyone else---besides kang chul---inside w? that's my big question.

like I said, I don't think it's more than a personification atm, but to say it's self-realized is a little too bizarre to wrap my head around. maybe, instead, it's like a brainless device come "alive" that is running on autopilot? which is to say that it could be driven purely by the characteristics/motives instilled by sung moo, & its aim is to fulfill its purpose in the story &/or sung moo's old intent to end kang chul. it's just a thought, but perhaps something about what drives the hooded figure's goal, or what it thinks/feels is the point of its existence, is so strong that it levels whatever makes kang chul special. I also wouldn't be surprised if this thing's unique features are the result of, or a partially due to, sung moo's fear/hate of kang chul.

I mean TBCH I have no clue! but it sure is fun to speculate.
I think Yeon Joo was also the original creator of the hooded killer, so he seems to have will. The "magic" to give life to the characters probably comes Yeon Joo. All characters created by it has its own life. In a romantic interpretation, the hooded killer may be the "evil" that wanted to end the happiness of Yeon Joo child (family problems) and Kang Chul the embodiment of someone who can fight (a child's mind can divide things good and evil simply), her father just took possession of the ideas seen in the drawing.
One of the possible reasons of the characters she draws its own life, was the desire to get away from family problems experienced by Yeon Joo child. It was the will power of Yeon Joo. Sorry for bad English.
Im sorry for this random question and my laziness (i couldve just looked it up in the episode I guess).

But I've watched all episodes that have aired so far but I don't remember it mentioning Yeon Joo as the original creator of Kang Chul. Is it mentioned in episode 5 or 6 or something? I guess I just missed it
Sujach, the moment of the episode is a flashback about the creation of Kang Chul, shows parents of Yeon Joo fighting and she sat in a corner doing some drawings while crying. That design was Kang Chul character holding a gun.