
can someone explain me the whole story? I mean I don't get it. What happened to kae?

In a world where normal people and 'abnormal' ones lives -albeit hidden, there will be a clear distinction between them.
The laws itself are 'on the side' of normal people, it might not be obvious but such laws are unfair to the abnormal people.
It was clear that many of abnormal people want just wanted to live their lives normally, melding completely into the society without the necessity to expose themselves in the open. They're fearing to be ostracized by the people around them.
Kae/Kei was a person who didn't have a clear direction in his life, maybe he was just want to live normally or maybe he was just need a companion with similar situation as himself.
In his 3rd year of High school, he met Hee Oong in somewhat bad first impression note. On early phase, they're often clashing against each other, but gradually became close.
After a certain incident -regarding how 'abnormal people' was being treated by the normal one, driving his already brittle sanity to disappear, Hee Oong had his suppressed personality unbridled, along with his esp; thus a personality change. And he also gained a purpose -to change the world of abnormal people. This was the seed of WONTED creation.
Hee Oong seems to see Kae as someone similar to him, thus tried to get him join his cause using various means and machinations.
of which he succeeded.
There is not much info about Kae's time in WONTED, but at a certain point Kae was betrayed by Hee Oong either in case of Ah Jin or because WONTED has changed its direction or because he was going to quit WONTED.
In the end of his time in WONTED, Hee Oong imparted Kae a geas/command to always pursue him.
After time skip of 6-7 years, Kae still in his hot pursuit of WONTED, but many other organization has sprung up and some even use his alter persona to frame him in some deliberate crime. And many hidden elements was added to the story. -about gargoyles especially.
After some time, Kae managed to confront Hee Oong. But Hee oong being Hee oong, he spilled the beans that the reason why Kae always chasing after them was his geas not due to Kae's own will, which shocked him greatly to the degree that made him unable to use his esp for a period of time.
Later, the story progressed in the direction of the interaction between Gargoyles and WONTED, which is still on going here...

I was kinda expecting yoonpil to become the villain, like that's kinda cool. Since songji acts badass and somehow looks like the villain, it will be such a major twist if at the end the personality that the A.I copied was yoonpil's and then flashbacks kicks in and shows how bad he became with some tragic backstories. And songji is the one who tries to stop yoonpil instead. I kinda want to see a badass yoonpil. Overall I cried! great art! great plot.. just a little sad that at the end, some of the forcers members still died.
When sunbae said something about fate on chap 9? When he said, "I guess we really are soulmates.." and those dreams that hosik was having about sunbae being an emperor and him being a servant. Maybe it was them in their past life. Like the part where the past master sungyeon said, "If you were a woman, I would have even made you my wife by getting you pregnant or something..” and the gods heard their wish or something and granted it on their next life which is the present time of the story.
1 out of 10 men has the chance of getting pregnant. And that 1% includes hosik (of course only in the story)
And there was also this line that got me
"Until young master chases me out, I'll be serving you for the rest of my life.." which kinda support my theory on them being fated partners. I don't want to make this cute funny and sweet loving story, but I just had to since I love making theories as such. Don't hate me for wrecking your peaceful mind HAHAHAHA
Yay