I see a lot of confusion about Yoyo boy. So let me clear things up.

If you've watched Goblin, you will know that there is a Godlike being that is one tier above Kimshin. This god has the ability to inhabit many different bodies, but in this case he chooses goblins nephew. The sole purpose of this god is to be able to the create rules that governs the ML, or in the case of KTEM, it's just a convenient way to explain away logic, because a god decided, a Deus Ex Machina as one poster has said.

In KTEM, we see a similar usage here, not surprising, since it's the same writer.

Yoyo boy is in essence, the flute. and the flute is a combination of the Fates (Greek Mythology)/and a god. I believe the writers intention of creating yoyo boy is the following:

The flute is an inanimate object, incapable of human behavior; but in reality the flute is sentient. The writer KES, wanted to humanize the flute, and the best way to do that is to create a sort of human avatar to display what the flute is thinking. So emotions like, the flute is calling out, or the flute is crying becomes easier to grasp when we consider the yoyo boy to be the flute.

When the flute is cut in half, so did yoyo boys powers and they show this weakened state in a few instances. Like when yoyo boy saves TE with a knife, and he shows his incapability to move thru dimensions. What limited powers yoyo boy had as a child we do not know.

We see the full extent of Yoyo boys power when the flute is made whole, and yoyo boy regains his true adult form. From this point on, we see that he gains godlike powers to enter into the subconciousness of different people, control memories of people, and change the time zone world own rules. We also get a superclip of yoyo boy imprinted into scenes with other characters.

These superclip of yoyo boy is intended to show us the audience that yoyo boy is actively changing fate. And this is where the contradiction may come, because there is a reason, it's called fate, it's suppose to be inescapable. Thus enters the godlike aspect of yoyo boy, where he even has the power to change the fate of people. So for example when we see SJ walking and sees TE in the window with her judo uniform, that is show telling us yoyo boy made SJ walk and notice TE, thus creating that particular fate where they meet.

Yoyo boy and the flute, also represent the Fates in greek mythology. There are 3 aspects of the Fates, namely the one who allots the lenght of the red string, the one who spins the string, and the one who cuts it. KES simplifies it by making it one being, yoyo boy. But I believe she may not have read the whole mythology, as the Fates typically deal with death, thus the cutting of the string, means you die, but this is not the case in KTEM. Yoyo boys even says "shall I break it", in the aspect of KTEM breaking the strings of Fate is interpreted as rewriting someone's fate.

And this is why we get so many happy endings in EP 16, because yoyo boy is able to change all these fates, that is the extent of his power. And yoyo boy, who is seens as god, also doles out god's punishment on the villains of the show by giving the villains poor fates.

And the flute, which is a representation of the powers of yoyo boy, and thus a god, is in the hands of LG.

You see, LG and TE were never fated to be with each other, it was only thru the use of the flute that they were able to meet in the first place.

But because LG now controls the flute, he is able to, for two days every week, change his and TE supposed fate. In many ways, LG and TE are cheating fate.

LG also becomes the yoyo boy, in the sense that he has the power in his hand to change people's fate. Just like he change Shinjae's fate by saving his life with the baseball.

And that is the ending we see.

It's less of a big deal in Goblin because they build up the romance and the rest is somewhat coherent.

This was just "here look at my yoyo

it will distract you from the fact there were so many gaping plotholes we just waved away with the fact I'm all powerful and can change everything".

I mean seriously. A 1 minute clip with yoyo guy could have been the entire show. Even the TV shows and movies that screw with your mind tell a compelling storing before doing the bait and switch. This one did not.

@Kimsamsoon 

I agree that the screnwriter could have taken some ideas from Greek but also Korean mythology. But let's not be fooled, the charakters had no influence on their own fate/destiny. It was planned in advance by yo yo boy. He pulled the strings. He needed people to restore the balance. He used them but rewarded them for that; by punished bad and rewarded good. And it wasn't Lee Gon who saved Shin Jae from the accident but yo yo boy, Lee Gon was just a tool in his hands. He sent him to him.

Like i've said from the start.

yoyo boy is a shipper. He shipped LG and TE from the beginning.

What I didn't like though, is how yoyo boy gave ALL the good guys happy ending, and punished all the villains of the show. It felt soooooo unrealistic that I had to scream. It was as if the show treated its viewers like children who cannot handle a few sad endings, quite insulting to be honest. 

A couple of Fates I would have changed.

Don't let LG fake dad die, but instead let LG fake family heal instead

Let PM work with the mom in the fish market instead of Jail with luna as her sister

Let the police chief show he had a second family, and the wife understanding that

Don't let JY parents get back together, what was the point of this?

Let JY and ES meet

And this part REALLY bothered me. Show that the Prince Buyeong when his only son died. It's so very very not realistic that Buyeong ended up being the same person when his child died at such a young age.

I'm sure i'm missing a few more fates, considering how much characters was in KTEM, but these are the ones i'd like to see made more realistic.

Thank you for at least making me understand 1 part of TKEM. Here's my theory. 

Yoyo boy is basically just an analogy for a bad fanfic writer. The way he puts his favourite couple together despite it being non-canon, the underdeveloped villain, the supernatural elements that are never properly explained, the way he self-inserts himself where it doesn't make sense. Its every trope we've come to expect of bad writing. 

The show actually meant to teach us what a world controlled by a bad fanfic writer would look like. We all thought the story was just chaotic, confusing and nonsense but it was all on purpose. It's a commentary for those that actually look to make legitimate criticism on the show. You can't properly criticise something that is intended to be bad writing. The writer wanted us to reflect on humanities flaws by making us suffer through a giant fanfiction controlled by a Yoyo kid. The signs were there since the Yoyo kid constantly reads books. The product placements are explained by this as well as Yoyo kid probably just likes chicken, kimchi and coffee a lot and incorporates these elements into his fanfic. 

Showing us that the fools are actually us for not understanding this deep reference. I suppose my IQ has still not reached TKEM levels at this point of my life :( 

lol, this is an excellent viewpoint.

Yes, we are not smart enough to enjoy KTEM in it's fullest :(

Yeah I thought the PM bit was super weird as well.

So Luna becomes her adoptive sister and Luna's personality and life completely changes.... but the Prime Minister doesn't change at all as a person and still becomes a politician and still goes to jail for roughly the same thing she did before (corruption is corruption even if it's a slightly different form).

I appreciate not everything would change but that seems to be the ONLY thing that doesn't change. Literally everyone else changes.

 Knavery:

Yeah I thought the PM bit was super weird as well.

So Luna becomes her adoptive sister and Luna's personality and life completely changes.... but the Prime Minister doesn't change at all as a person and still becomes a politician and still goes to jail for roughly the same thing she did before (corruption is corruption even if it's a slightly different form).

I appreciate not everything would change but that seems to be the ONLY thing that doesn't change. Literally everyone else changes.

Ji Hun's dad still dies, even though LR isn't there to kill him. So that is the same. The Chief also doesn't change, he still hiding things from his wife.

 Knavery:

It's less of a big deal in Goblin because they build up the romance and the rest is somewhat coherent.

This was just "here look at my yoyo

it will distract you from the fact there were so many gaping plotholes we just waved away with the fact I'm all powerful and can change everything".

I mean seriously. A 1 minute clip with yoyo guy could have been the entire show. Even the TV shows and movies that screw with your mind tell a compelling storing before doing the bait and switch. This one did not.

I agree completely!