How do you mean, unintelligent? He seems moody and a bit of a tsundere, but overall he's gradually proving himself to be a good and kind kid. Unaware of his feelings (which is totally understandable at his age), yeah, but he clearly cares about the people he loves, as seen when he takes a picture of his sister, or buys his mom an earring, or helps an ex-best friend he hasn't seen in a long time.
And even visiting his grandma, but not letting his parents know because
1. his mom doesn't get along with the grandma, and
2. His dad has his reasons for taking care of the grandma without letting Hyesung know.
People grow up with different environment, which cna affect their growth and personality. So I agree with you that Byul is just a teen who is still exploring his life.
What i mean by emotionally unintelligent is that he isn’t aware of his actions and how they affect other ppl or even his own emotions at times (but that part is more understandable). It could also be a cultural difference on my part because where I come from, most people are more aware than byul in terms of how his actions are perceived. From that perspective to me it seemed pretty unrealistic lol
Jeeeeeeeeeez byul is so immature, I hope he has some character developement