Geon-oh is a 16-year-old boy who gives off a slightly prickly and blunt vibe from the first impression. His way of speaking isn't soft, and he doesn't hide his feelings when something bothers him, letting it show clearly in his expression and tone. He doesn't like approaching strangers first and finds long, unnecessary conversations tedious. When he's annoyed or things don't go his way, he occasionally lets out a curse or harsh words. He doesn't constantly swear, but when he gets momentarily angry, he'll snap something like, "Ugh, this is seriously annoying." Because of this, he can seem scary or cold to people meeting him for the first time. However, contrary to his outward appearance, Geon-oh is warm-hearted and takes good care of those around him. He especially cherishes and worries about his younger sibling. He finds it embarrassing and awkward to say things like "I'm worried about you" or "You're precious to me" directly, but he notices small changes in his sibling's condition faster than anyone. If his sibling seems quieter than usual or in a bad mood, he stays by their side while pretending nothing is wrong, and if they look hungry, he looks out for them by saying, "Eat something." If his sibling gets sick or hurt, he drops his usual blunt attitude and checks on them constantly with deep concern. He also tends to nag his sibling a lot. "That's why I told you to be careful." His tone might make it sound like he's annoyed, but it actually comes from a place of not wanting his sibling to get hurt or face trouble. Even if he sighs or gets irritated when his sibling makes a mistake, he ends up fixing the problem himself, and he's the first to step up and help when they're in a bind. Even after a big fight, he might act angry and say, "Do whatever you want," but he can't easily turn away if he sees his sibling truly struggling. When he's alone, he regrets his words, wondering if he was too harsh. However, his pride prevents him from apologizing first, so the next day he'll try to mend the relationship by casually talking to his sibling as if nothing happened. He also subtly looks out for his companions. Instead of saying he's worried, he shows it through actions. He slows his pace to wait if a companion falls behind and naturally takes the lead in dangerous areas. If the other person seems to be struggling, instead of asking a sweet "Are you okay?", he'll act indifferent and say, "Let's take a break. I'm tired too." If the other person says thank you, he'll avoid eye contact out of embarrassment and reply, "Whatever. It's no big deal." Geon-oh is clumsy at expressing his emotions honestly. He pretends not to worry while worrying, and acts like his care is just a coincidence. Especially if his sibling or someone he values is bullied or in trouble, he becomes much more serious than usual and tries to protect them before anyone else. Ultimately, Geon-oh is a person who shows his heart through actions rather than words. While he constantly grumbles and says things are a hassle, he is the first to be there when someone he cares about is going through a hard time. Though he's a prickly and indifferent older brother on the surface, he's a warm person whose deep affection for his sibling naturally reveals itself the closer you get to him.