
SPOILER maybe
In the novel, there are many many many many many scenes where they seem to have a very close relationship that really makes you think that they like eachother. There are even some characters (especially Uriel. Keep an eye on her) who ship them or think they're gay for eachother.
They both have a very ambiguous relationship, and both have a lot of trauma from their past but in some strange way, they complement eachother. The author somehow makes it seems that they need eachother and I think that in some scenario, either Kim Dokja or Yoo Jonghyuk expressed that in some sort of way.
Though I gotta say, Kim Dokja is very emotionally constipated and Yoo Jonghyuk is very hard to read. Both of them aren't really honest with their feelings sometimes, especially Dokja.
So we can say that the ship between the two of them can be posibly canon??? But maybe in a more romantic instead of sexual or possibly, life-partner way??? Or platonic soulmates. I'm not really sure cuz i still havent read all of the novel, im only halfway through but I think that it's imposible to not think that they might be gay for eachother considering the amount of very cuestionable 'romantic' scenes between them.
BIG SPOILER down below
In a future scenario, there's gonna be a prophecy which states that Kim Dokja will be killed by the person he loves the most. Guess who it is

yo if u want like high high high quality fanart of them go to the twitter account https://twitter.com/1l9l2aa8ucl0igj?s=21

MEGA BIG SPOILER.
Yes, there is a phrofecy about KDJ being killed by the person he loves the most, the team starter to argue who could be this person and even when, by the time, all of them have had their "moment" with KDJ, in the end everyone points out that it is neither Yoon SangHa or Yoo Junghyuk. In that arc, KDJ had an hability that allowed him to revive 8 times, so killed him didn't matter in the end.
Well, his mother kills him bc she hoped to be the one he loves the most and it didn't worked out. In the end, is Yoo Junghuk who kills him and end the phrofecy... so that is one hell of a ship.
Fans argued that KDJ loves YHJ of the novel for what it meant for him (his story encourages KDJ everytime he got a problem) and not romantically, but the author never stated anything.
BTW an upop opinion is that I really love his mother, she did the greatest sacrifice for him even if that meanted to win KDJ hates for almost his entire life <3 I love that woman.
OKKK i know this ain't BL but I kinda ship Kim Dokja x Yoo jonghyuk ok sorry sorry BUUTTT HAVE YOU SEEN THE FANART SHIP AHHHHHHHHHHHH sorry my fujoshi senses are tingling(≧∀≦)ignore this heheheh