
hyo un was and has never been a normal human. normal human logic simply doesn't apply to him. his extremely sudden growth in front of taehyuk's eyes is proof of that, so much so even he can't make sense of it because it simply d o e s n' t make sense.
you're wasting your time and breath trying to find the morals in this because he's not human to begin with. taehyuk is well aware that he too can't apply his human logic, it's clear that THAT is the author's intent.
oh and, try not to take fiction too seriously too. it helps.