Let's Share Theories!

I think Dried Squid Fairy was Haru's friend or was close to him somewhat in the historical comic, hence why he got so mad at him for trying to do everything Dan Oh wished for, and in turn he ended up getting hurt instead and even disappearing. From what I felt about the scenes the Fairy and Haru shared, the way he warned Haru felt like he was trying to protect him from hurting himself, like he knew something like this could happen, maybe Haru tried the same thing in the historical comic and got hurt? I think the Fairy just wants to stop Haru from hurting himself further.

I almost forgot about Haru looking at Nam Joo's father like he recognized him too omg I think everyone is connected somehow from that historical comic. Maybe the writer of "Secret" and "Flower" is the same one, and she/he is reutilizing the same characters?

I so agree about the fairy being very suspicious, even a bit creepy sometimes; like when he warned Haru about the consequences of not stopping Danoh (since, supposedly, that was the reason for his existence); or when Haru touched the doll on the stage and got hurt, he told him "that's what happens when you touch things that are not yours" (or something like that xD).

But his real motivations are the ones I can't figure out. I mean, out of the theories you guys posted (I agree btw), which one seems more possible? It could be that he's indeed trying to protect Haru from another ill-fated ending in this new comic (in the case he somehow came from another comic through the black hole; or if they all were reborn/rewritten in this comic as new characters).  Or maybe they were rivals in that other comic (probably a joseon/historical one, due to reasons explained in a previous comment) and he's just making sure Haru fails this time again out of revenge!?  I really don't know!

I also thought he could be the writer, who for some strange reason found a way to enter his own stories like in the kdrama W. And his only purpose there is to guarantee those 'self-aware' characters follow the script as intended and block any rebellion that could change the storyline...but sometimes I doubt it, since it would be too obvious, I guess?

I think the scar on Haru's hand done by Dried Squid Fairy
The guy with long hair in Flower story talking to Haru is him

and that Flower mean "It was said that when the couple met after death, they vowed to meet each other after reincarnation. However, neither of them could keep their word."

my theory
"Flower" comic belongs to the chosun era
Baek Kyung was a noble there and Haru was his loyal close servant, his job is  protecting Baek Kyung
You can see he do it twice out of habit , protecting him from a Basketball ball and protect him from punching window and say he going hurt himself
Baek Kyung seem care about him too, remember what he say to Haru  after Tennis game ?!
Dan oh is Baek Kyung fiance and a princess. remember the sequence they visit an old house and Dan Oh say that place look familiar and jokingly say she must be a princess in her past life
They seem lived in that place in Flower comic
That's why Haru know about that lake, he visits that place with Dan Oh in past, that's why he asked her if she knows about that place because he can remember things from past
In Flower Haru falls for Dan Oh and she loves him back too
Dan Oh die there, the writer always kill her and Haru try to change this destiny
And it's sound weird but I think Baek Kyung mom, who died,  is the writer
Haru never been ML

 Kim MC:

"Extraordinary You" is my obsession right now.

I believe authors, wittingly and unwittingly, place themselves as a character in their books.  I read one author describe the person who resembled her the most in her novel as an "observer" or "narrator out of scene". That being said, from the time this drama began, I've been on the Sherlock Holmes trail of trying to figure out who the writer could be.  I don't think Dried Squid Fairy fills that part and agree with the opinion he was a character from another written piece.  Honestly, how he fits into the present storyline kind of dominates my interest because he is the narrative voice of reason and consequence with the "aware" cast.  Since torturing Dan Oh seems to be the author's prerogative,  I draw a blank as to who her nemesis is at this point in the story.  This has to be the most original storyline I've ever come across!  

Wow that's a very interesting info! So, let's say the fairy isn't the author, since he isn't exactly omniscient. He knows a lot because he's been aware of himself for a long while and knows about the two comic books; but he seems equally intrigued and surprised about the recent changes in the story.  But who else would fit that role out of all the characters, so far? Or maybe we haven't been introduced to every "aware" character and there's someone who will show up as her nemesis, as you said...the one who's determined to give her a tragic ending this time again. Because right now, Danoh, doesn't even have a rival (I think). Btw, this drama is my current obsession too xD I started watching this out of curiosity, since I don't watch teen dramas regularly like I did years before. But surprisingly, this turned out to be an awesome and very different story so far!

Okay!

That's not a theory but I think it is strange. So I think we all agree that Dried Squid Fairy was in the same story with Haru. But in 13-14 ep when they had like a sport thing and Fairy was preparing the food he said to the writer something like "Why didn't you give me short sleeves and why this students never study? This comic is so unrealistic” It seems like he knows what a real school shoud be like. But if he is from a historical comic it doesn't make sense. How could he know what a real school looks like? If he went from "Flower" straight into "Secret" then the only school he would know of is the school we see. And I don't think the school was changed from a normal to a "being perfect to find love" one.

And  something else. If we compare W and Extraordinary You...

We never saw the real world in Extraordinary You like we did in W, we never saw the writer and characters have never escaped the comic's world. What if Dried Squid Faury did? What if  he escaped? Or what if he was from the real world but enter the world of comic books and now he can't get out?

Ayee  I'm pretty sure both Dano Oh and Haru are from the other manhwa since in the "portal" we see them both talking to each other about changing their fate and all that. I'd say that scene we see there is one of the scenes that took place in the Flower manhwa after they both gained awareness. What Dan Oh said to Haru in that scene is a mirror of what Haru said to Dried Squid Fairy about finding the answer of their existence with Dan Oh.