
This is the explanation, NOT justification, for who Jaekyung was and has become. Unfortunately, even though he was shown some kindness and direction to crawl his way out of ab*se and poverty, the path was through boxing. He literally fought his way out through his fists. It wasn’t a warm home, warm clothes, or loving emotions that nurtured and saved that little boy. He fought his way from the bottom, through blood and sweat, and never learned proper emotion or love nor have it modeled to him. Villains aren’t born, they’re made. He needs to learn how to love, and so does Dan, because they’re both broken in their own way. Jaekyung a little more so, in terms of being emotionally stunted.
With that backstory, the way he treats Dan’s grandmother doesn’t seem so strange or fake anymore. It’s a long road ahead but hopefully the author spends a FULL arc on Jaekyung growing past his “fight to live” and solving problems w fists phase to be a real human before ending up with Dan. Otherwise neither of them can be complete, alone or with each other