don't know if you wanted a serious answer haha so u can just ignore this :)
hyunjae is definitely one of the life forces of the story but initially he's supposed to be played off as another lofty and mighty s-class, so when you find out more details about his background it comes like a game changer. imo the novel does a better job of making hyunjae more alluring and weird than the manhwa does because i feel like for the first chapters he shows up a lot less which gives the reader time to get used to his presence, then it proceeds to slowly breaks apart his character until you understand (and even crave) his presence. idk if that explained anything but i tried my best to avoid spoilers hehe.
90% of the time Hyunjae is kinda irrelevant to the plot (no fr, why him? We’ve got other characters as well XD) but im not complaining coz author is actually feeding us fan service with the explicit bromance (▰˘◡˘▰)