Yeon-joo does not have the slightest idea how to explain the existence of Cheol’s parallel universe, so she starts investigating the only place with potential answers- her dad’s annotations. But Seong-woo’s authorial notes aren’t special features intended for reader enjoyment. They’re surprisingly painful recollections of a difficult time in Seong-woo’s life, and how the main plot movements in “W” were all reactions to Seong-woo’s emotional state. That is, until Cheol took on a life os his own and started building Seong-woo’s life much as Seong-woo built Cheol’s.
“W” is imminently intriguing as an explanation of the relationship between an author and his creation. The relationship between Seong-woo and Cheol hits all sorts of interesting beats that anyone who has ever tried to seriously write a story can understand. Even though Seong-woo created Cheol, he can’t control him because Cheol has his own distinct sense of motivation. Seong-woo can’t force Cheol to act a specific way except through external circumstance, or else Cheol’s actions will feel unnatural and poorly written.
And Cheol maintains all of this depth within his own world as well. Observe how even though Yeon-joo keeps trying to engage Cheol as if he were a cliché, the man manages to keep surprising her again by acting like…well, by acting like a guy who has seen all sorts of strange suspicious stuff, and can only stay alive through constant creative thinking. Cheol seems to have figured out that whatever external force is preventing him from solving the mystery is not bound by coherent logic.
This, I think, is why Cheol is so drawn to Yeon-joo. Her behavior from the very beginning has made it clear that she thinks in the same mysterious logic as Cheol’s creator. For the hooded murderer of Cheol’s family to appear and disappear without leaving a trace makes no sense rationally, but it does make the same kind of irrational sense as Yeon-joo forestalling attempted murder and solving problems with unprovoked kisses.
Unluckily for Cheol, as a technical spectator he lacks the ability to make use of such meta-reasoning. You can perhaps see how this all works to put the basic narrative of “W” in a fairly baffling place- but in a good way. The storyline is so completely off the rails it’s impossible to guess what’s going to happen next. Incidentally, don’t watch the preview. “W” lives and dies on the power of its plot twists, and the preview spoils several of them.