📍 A subscriber’s comment today pulled the trigger on something I’ve been wanting to dig into for the longest time:
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This post contains copyrighted material from “Weak Hero” (© Wavve/Netflix) used for educational analysis, criticism, and commentary purposes under fair use doctrine. All rights belong to original creators.

“Unpopular opinion: Si-eun is a psychopath. He seemed like an amateur at fighting physically, but not mentally – like he’s thought of it before. The way he just acted without thinking when Yeong-Bin provoked him, stabbing someone and breaking his nose. Si-eun is not a normal boy, he’s manic. Physical isolation, enjoying violence – these are the signs I get from him.”
While I wouldn’t go as far as calling Si-eun a psychopath, this observation struck me because it touches on something that’s been gnawing at me since my first viewing: there’s something profoundly unsettling about the violent undercurrents that run through this seemingly perfect honor student.

I’ve been thinking about Si-eun’s character for weeks now, and I was completely hooked on Si-eun when he stabbed Tae-hoon’s hand with a pen and wrapped Yeong-bin’s face with the curtain before smashing him with a book. Since that moment when Si-eun literally wrapped Yeong-bin up and obliterated his nose with that book, I’ve been absolutely fascinated by this character.
I’ve been turning it over in my mind like a puzzle with pieces that don’t quite fit the way they should. The more I watch, the more I’m convinced that most fans – especially those of us who’ve binged this show countless times – have picked up on the fact that Si-eun carries something dark within him. Something that goes far beyond typical teenage angst or academic pressure.

There’s this moment in Season 1 that keeps haunting me. When Seok-dae’s crew tries to pass Si-eun drugs by mistake, and Seok-dae immediately backs off, telling his guys “pick your fights carefully – he was about to stab you with that pen.” It wasn’t fear I saw in Seok-dae’s eyes – it was recognition. He saw something in Si-eun’s cold, calculating stare that screamed danger, something primal and barely contained.

“…pick your fights carefully – he was about to stab you with that pen…”
Park Ji-hoon’s performance in these moments is extraordinary. The way he can look so detached and innocent while radiating this barely-contained violence… it’s like watching someone hold a live wire while pretending it’s just a piece of rope.
But what fascinates me most is the paradox at Si-eun’s core. Here’s a boy who’s literally the top student in his school, with an insanely high IQ, yet he’s carrying around this explosive potential for violence. When he tells Yeong-bin’s crew “don’t bother me,” there’s something in his delivery that sounds almost like a dare. Like he’s secretly hoping someone will push hard enough to justify unleashing everything he’s been holding back.

“Don’t bother me”
I’ve been thinking about what makes Su-ho so drawn to Si-eun, and I don’t think it’s coincidence.
Su-ho is a fighter – a kid very familiar with violence – and I believe what initially caught his attention was Si-eun’s refusal to submit mentally to Yeong-bin’s group. (Of course, it’s important to note that Su-ho doesn’t abuse his fighting skills…) If Si-eun had cowered like other bullied kids, if he’d shown the fear and submission that bullies expect, would Su-ho have even noticed him? I don’t think so.
Su-ho didn’t give Si-eun permission to be violent. Rather, he recognized and was drawn to that raw, untamed energy hidden beneath the model student facade. It’s like Su-ho saw the real Si-eun before Si-eun himself understood what he was capable of.

By Season 2, something fundamental had shifted. I sensed that Si-eun was actually longing for violence – not in a sadistic way, but as someone who’d discovered that physical confrontation was the only thing that made him feel truly alive. He’s emotionally dead, dependent on medication to sleep, haunted by internal conversations with Beom-seok. When Seong-je appeared, it felt almost inevitable. Here was someone who could provide pure, uncomplicated violence – no emotional baggage, no psychological complexity, just raw adrenaline.

Their rooftop fight scene represents everything Season 2 was trying to say: Si-eun finally finding an outlet for his aggression without having to protect anyone or navigate complex emotions. It’s violence stripped of context and consequence, which is perhaps the only kind Si-eun can truly embrace without guilt.
(If Seong-je hadn’t stopped him, I believe Si-eun would have genuinely punctured Seong-je’s eyes with those broken glasses stems. And unlike Seong-je who fights with technique, Si-eun truly fights like an animal, screaming and thrashing with raw instinct…)

But the roots of Si-eun’s psychology run much deeper than teenage rebellion or academic stress. The more I learn about his background, the more tragic his story becomes. Si-eun’s parents essentially abandoned him emotionally. They expected him to raise himself while maintaining near-perfection. His father, an Olympic silver medalist in judo, was clearly disappointed that his son turned out frail and injury-prone.
The detail that breaks my heart most: as a child, Si-eun overheard his parents arguing about whether they should have had him. They were both regretting their decision. His father demanded to know where his mother was when Si-eun broke his arm, and she shot back that she only agreed to have him because they were supposed to raise him together.
Imagine a child processing that level of rejection. It would fundamentally reshape how someone approaches every relationship for the rest of their life.

So Si-eun adapted. He became an isolated, stoic, scholastic machine, living in an extremely rigid world where he systematically denied himself basic needs for food, sleep, and human connection. When pressure like that finally finds a release valve, the explosion is inevitable.
What strikes me about Si-eun’s violence is how it serves dual purposes: it’s both the tool he uses to break through his shell of isolation and the method by which he protects himself. It’s calculated, surgical almost.
I think what makes Weak Hero so gripping is how it refuses to offer simple moral judgments about violence. The show doesn’t justify Si-eun’s actions, but it also doesn’t condemn him. Instead, it breaks down violence into multiple layers and dimensions, viewed from different angles depending on circumstances. Si-eun embodies this perfectly – someone forced to use violence to counter violence. Newton’s law applies here: for every action, there’s an equal and opposite reaction.

The beauty of Si-eun’s character lies in how the writers refuse to give us easy answers. Is his violence justified? Necessary? Healthy? The show presents these questions without providing comfortable moral conclusions, which is exactly what makes him so endlessly fascinating to analyze.
Si-eun definitely has serious violent tendencies, but his violence serves as both a tool to shatter the isolation he created and a means of self-protection. What haunts me most about Si-eun is how his story asks uncomfortable questions about what we’re willing to accept in the name of survival, and whether someone can choose violence as a tool without being consumed by it. I suspect the answer is more complicated than any of us would like to admit.

Park Ji-hoon’s nuanced performance makes every moment of this transformation feel authentic and inevitable. Watching Si-eun’s journey from isolated honor student to someone who can embrace his capacity for violence is like watching a masterclass in psychological complexity.
This exploration barely scratches the surface of what makes Si-eun such a fascinating character.
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📊 Quick Navigation by Interest
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- Why Si-eun is a Character Magnet
🎬 Behind-the-Scenes Content:
🌐 Translation & Cultural Context:
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Oh. I disagree that Si eun is longing for violence in s2. He’s actively trying to avoid it. But on the rooftop with Seong je … well there’s a lot to explain the intensity of that fight. There’s the adrenaline and panic from running to the scene to try to save Jun tae who has no defence skills. And then there he is … this scary psycho guy who obviously wants to beat Si eun severely. The guy who came out of nowhere to threaten and attack him, for no reason at all, in a museum bathroom. The guy who threatened a -completely defenceless- Su ho at the hospital. Who had overridden Na Baek Jin’s guarantees for who knows what reason … and totally laid waste to two of his friends on that rooftop. And then he turns out to be the toughest guy that Si eun has ever had to fight. Strong, skilled and smiling in that incredibly unnerving, slightly psychotic way that he has. So, Si eun is kinda out of his depth and has to dig pretty deep to not get completely wasted himself. I didn’t see any moment when he was going to shove his only weapon into Seong je’s eyes. I don’t think he was on top of things enough to have had any chance at that. So, yes, it’s quite a violent fight … but did Si eun really have a choice about raising his intensity? Respectfully and all … I don’t think so. I agree that his trips off the deep end in ep1 and ep8 of s1 were really hard to watch … disturbing. But s2 is different. I think he knows what he’s fighting for in s2 and it’s to end the cycle that he and his new friends are caught up in. He’s not out there looking for opportunities to get violent. Gotta admit, though, that I’m a little worried about myself being so defensive on the part of a tv character 🙂 haha. bfn Jennie.
Elaine, thank you so much for always leaving such thoughtful comments!
Even while working… even during my commute, ideas suddenly pop into my head or thoughts come up, and even though it’s been quite a while since I watched this show, I still have so much to say 😂 If I just keep all this in my head, I’ll forget it someday, so I started this blog to record these thoughts. Having you come here and always leave such considerate comments… I can’t find words beyond “thank you so much” I’m truly grateful 💗
And I think subscribers 😂 have noticed that I’m like Beom-seok’s lawyer 😂 Just kidding 😂😂😂 I even bought the script book to try to understand Beom-seok, but honestly, if I had a friend like that around me in real life, I probably would’ve found it hard to handle too. So I get what you meant at the end … worrying about spending this much time on a TV character 😂
But I really think this drama has had a lot of… positive influence on us. There’s a Korean joke… (I think I might have told you this before) “A savior who came to destroy my daily life” that’s exactly the vibe Weak Hero has 😂
Yeah, about Si-eun’s inherent violence … I’m trying to organise my thoughts more and plan to post about it. I’ll probably be the last person discharged from the mental hospital, and I don’t know when this unpaid lawyer 😂 role will end, so I’m getting a bit worried about myself too 😂
You’re like Beom Seok’s lawyer? Well you can put me on his legal team too. And that monster we will loosely call a ‘father’ should pay us one huge boat full of money to keep his name out of the papers or we expose him.
haha. You know I love your channel as well as WHC; my two saviours who came to destroy my daily life.
Let’s worry about our mental status later … 🙂 … much later.