Krs!cale - Tumblr Posts
KRS!Cale: It's also a great stand in for wood varnish, window cleaners, pesticides, gasoline, vaccines, hair-growth syrums, cooking oils, war rations, holy water, the primordial sea, and is a very strong nuclear reactant :)
Og!Cale: ....What the actual fu—
Og!cale: I have these sevem products for my skin, these five for my hair and these three for the rest of my body
KRS!Cale: oh I have this one product for all my body and the floor of my house
Og!cale: ...
THIS! THIS IS WHAT I WAS TALKING ABOUT IN MY OTHER REBLOG!! Love it or hate it, this is literally the truth.
Cale Henituse and Kim Rok Soo
After I posted yesterday, I saw an opinion that I kind of agree with about the difference between Cale Henituse and Kim Rok Soo.
I'm gonna say my opinion without trying to offend the whole fandom. Again, you can read fics about OG Cale as MC. I will not stop you just because I have my own opinion. You are free to read whatever you want. If you don't agree with this, it's fine and if you do, don't antagonize or attack the fanfiction authors who made these fics. Let them do their own thing, okay?
This post is not a rant but me sharing my own thoughts and opinions about this topic.
To make this easier, I'll call OG Cale as Cale and OG KRS as KRS.
[✋SPOILERS for the first part of the novel✋]

Some say that Cale Henituse and Kim Rok Soo are the same person. While I don't know if this is true because I haven't read the second part of the novel yet, in my opinion, they are not the same.
Again, I repeat, I like Cale Henituse. He's very intelligent and kind to Basen to the point of destroying his own reputation, he targets thugs and scammers whenever he's "drunk", he's willing to sacrifice his whole identity in order to save his world after surviving for twenty years by himself. He's a complex character and in another world, if given the chance, he would've been a great MC.
But that's the thing, he is not the MC of TCF, Kim Rok Soo is. And I think some fans forget the reason why Kim Rok Soo became the MC and not Cale Henituse. Because in some fics that I see whenever I scroll down to look for something to read, Cale completely replaces KRS' presence in the story, to the point that he doesn't exist anymore.
Let me explain.
Kim Rok Soo
Kim Rok Soo is a very integral part of the story. You can't easily replace him with another person, normal or otherwise, and expect the story to go the same way it did in the novel. He did things his way because he's a chaotic little shit. He's a different person from Cale, no matter how many or few similarities they both have.
It's not because he's simply smart or OP (as some would say) that he won a war that ended in only two years, but it's also because of his past and the bonds he made as himself.
He's a person full of empathy for these people that he meets wherever he goes, regardless whether he knows them from a book or not, because he understands them and their pain. He does not hide his personality and in a way, his charisma attracts these people who see him for who he is, a kind person.
Kim Rok Soo is different because he survived in an apocalypse by himself until he meets Lee Soo Hyuk and Choi Jung Soo. Plus, he did not have a great childhood. He was abused and lived by himself for the rest of his childhood and teenage years because of a curse (or maybe because his uncle is just a shitty person, who knows).
The opinions he has and the way he thinks are shaped by his own experiences. He is the Kim Rok Soo we see in the novel because he grew up under these circumstances.
To say that he's easily replaceable would be too disrespectful to the sacrifices he made as both Kim Rok Soo and Cale Henituse.
Cale Henituse
Cale, on the other hand, is different. He lived alone for how many years because he deliberately pushed everyone away because of his grief and after what Jour told him. It's not because of a curse that he became this way but because he chose to.
Yes, everyone he knows should've tried to make an effort by comforting him or talking with him (his family, the nobles he's close to, Ron and Beacrox) but that did not happen because he's the one who chose to live like this. I've mentioned it in my post about Deruth but if a person doesn't want comfort or doesn't want to talk, they will not talk, especially someone as stubborn as Cale. To blame all these people (including the kids) and the rest of the world because of his own choice is simply not right or fair since the only one responsible to actually help him is Deruth. Violan is not given this chance nor did she try as his stepmother but it all comes down to Deruth. But of course, he did not get any help nor did he seek any.
He lived his years shrouded in grief until the very end. He's a kind person but unfortunately, life is not kind to him.
Later, he survives in the war until the White Star kills him. What did he choose to do in the end when he made that deal with the God of Death? To return to the past so he can save everyone? No. Instead, he chose to go to KRS' world to find his mother. If CJS were given the chance to decline a proposal, why didn't Cale? He could've said he'll do it himself but instead, he left it to KRS. We all know he's stubborn enough to ruin his reputation, is he not stubborn enough to make a deal to save his world as himself?
You can argue it's maybe because the God of Death didn't give him the chance to argue with it but there are other ways the god could've sent KRS to this world. Like Choi Han or Choi Jung Soo.
Choi Jung Soo
Choi Jung Soo is a prime example of what could've and couldn't have happened if he agreed with the God of Death's proposal. He is not KRS. He has his own opinions and experiences that make him unique. He is not like Choi Han who drowned in his despair in TBoaH but instead, is a man who wants to survive with his friends (brothers) and smile with them despite the pain he suffers in.
If he were to replace KRS, the story would've gone differently. He might find Choi Han and they would do their best to survive in this new world together. He may or may not find Raon and the kittens, depending on the time and location when he arrives in this world. Alberu may or may not completely trust him like how he didn't completely trust Choi Han in TBoaH because unlike KRS who is too similar with Alberu, CJS is different. He might not look for the ancient powers since he has his own ability, leaving some that the White Star could've taken like the Sky Eating Water and Super Rock. In fact, the shield could've been left at the tree unless CJS knows about it and takes it. (Let me remind you that no one in this world knows there's an ancient power in that tree in the Henituse territory.)
I can list down things he could've or couldn't have done but it might be too long.
But my point is, it could've been Cale, Alberu, or Choi Han who were sent to the past but the story would've gone differently because these people are all different in their own ways. Heck, if the God of Death truly wants to save this world, he could've sent back Choi Han or Alberu instead of Cale. Because these two are also powerful in their own ways that do not need the help of ancient powers. Just give them enough information and they could've ended the war faster than twenty years.
Conclusion
So, yeah. Kim Rok Soo became the main character for several reasons. He was an ability user and team leader back in his world, he has the curse attached to him because of the White Star, he was an abused kid who had a sad childhood.
And I think there are other reasons why, if KRS is not the MC, that the story could've ended differently. Put aside Raon who is powerful and has a connection to Sheritt and the Dragon Slayers and would be integral to the story, On and Hong could've died with no one knowing about them because they were barely mentioned in the books. Mary could've stayed in the City of Life because no one would need her to help Ron. Hannah and Jack could've died because no one would've known that they were killed. Paseton has a chance to live but no one knows where he is.
Some characters would live and some would die if Kim Rok Soo is not the main character. That's basically what I think about all of this.
The reason why they survived, aside from the books, is because Kim Rok Soo's heart is so big that he wants to help people or give them the chance to survive. Some people would ignore or not notice these people because they have their own problems to deal with.
But Kim Rok Soo just wants to live. And I think that's why the story went the way it did.
Kim Rok Soo, the man who became Cale. His life motto was pretty simple.
Living long without pain. Enjoying the small joys of life.
Living a peaceful life.
- Chapter 2: When I Opened My Eyes

Again, I'm not stopping you from reading these fics nor am I telling you to attack fanfic authors because of what they write. This whole post is just me sharing my opinion.
You don't have to agree with anything I said. You can ignore this and read whatever you want to read.
This is not a post undermining or disrespecting what Cale sacrificed and felt as a person. This is a post to share my opinion that Cale and Kim Rok Soo both deserve the respect that they should get for everything they did and to not completely erase a character for the other. But if someone does it, then I can't do anything about it.
As a Mob Psycho 100 fan, I will end this with one line that perfectly summarizes what I think about this topic.
Your life is your own.