Weak Hero Class 2: The Seong-je & Si-eun That Had Us All Hooked

📍 As we approach mid-July, which aligns with Su-ho’s coma in the Class 1 timeline, I’m planning to wrap up my Weak Hero fever (which has been like a summer cold…) by organising the scripts from my YouTube videos into blog posts. The early videos I uploaded were quite rambling, so I wanted to refine them into properly structured written content. This post is a compilation of two audio contents: “Weak Hero 2: Si-eun’s Pain, Seong-je’s Game 1” and “Weak Hero 2: The Seong-je Effect.”

When Park Ji-hoon Became an Actor, Not Just an Idol

Honestly, I had no idea who Park Ji-hoon was as an entertainer before watching this drama. But after watching Weak Hero, Park Ji-hoon became permanently etched in my memory as Yeon Si-eun. It’s been such a long time since I’ve been so immersed in a drama where I saw the character itself rather than the actor – it was such a refreshing and amazing experience.

The Walls Get Higher

When Si-eun gets forcibly transferred to Eunjang High School, he builds even higher emotional walls than he had at Byeoksan. The trauma of Su-ho falling into that coma? It’s carved so deep into this kid that he’s basically trying to live like a ghost – quiet, ordinary, invisible. But here’s the thing about jungle-like classrooms: they don’t give a damn about your trauma or your desire to disappear.

Hyo-man sizes Si-eun up as some pathetic loser on his very first day at Eunjang and immediately starts picking fights with him (until rumors about Si-eun being a psychopath start spreading and the kids basically make Hyo-man ‘burrow’ – their word, not mine 😂). Meanwhile, Seong-je zeroes in on Si-eun as his shiny new dopamine source.

So Si-eun ends up facing his sophomore year at Eunjang in a situation that’s the complete opposite of what he’d desperately texted Su-ho: I just want to be left alone…

Fighting with Purpose vs. Fighting to Survive

What’s really noticeable about Si-eun in Class 2 is how his fighting seems to have leveled up a bit from Season 1. He’s got what fans jokingly call his “weapon starter pack” – that signature pen action is still there, but now he’s branching out.

That rooftop showdown with Seong-je – what fans dubbed the “alchemy battle” – is honestly the best part of Class 2. Both Park Ji-hoon and Lee Jun-young have spent years as dancers, and like the directors said, it really shows. The whole thing flows so smoothly, almost like watching choreography instead of a fight – it’s just really well done.

But what actually got me hooked on this scene was the mind games between them…

The Micro-Expressions That Kill You

Here’s what really gets me about Park Ji-hoon’s acting – when you look at Si-eun’s opponents like Young-bin, Gil-su, Woo-young, Hyo-man, and now Seong-je in Season 2, they’re all way bigger than him physically. But Si-eun has this intense focus and this calm intelligence that lets him turn the tables. Park Ji-hoon’s performance in those split-second moments is just incredible – you can see the obsessiveness, anger, killer instinct, desperation, urgency, and even fear all playing out. And in that rooftop scene especially, Si-eun fights way more like an animal than we’ve seen before.

It’s all in the subtle facial expressions, the low-tone delivery of sparse dialogue, and the slight trembling of his eyes and muscles. The transition between his emotions inside and outside of fights is seamless.

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My personal favorite scene isn’t even the rooftop fight – it’s that tunnel confrontation with Hyeon-tak. When Hyeon-tak mentions Su-ho (Si-eun’s trauma trigger) saying “What, you completely fucked up one person’s life, so don’t act all nice, you hypocrite,” the direction is incredible. A train passes behind Si-eun while the OST track “RUN” plays, and when Hyeon-tak hits that nerve, Si-eun’s eyes change as he lunges forward. Park Ji-hoon’s portrayal of these subtle emotional shifts and bubbling guilt is absolutely masterful.

Lee Jun-young’s Seong-je:

The character that keeps me coming back for more in Season 2 has to be Geum Seong-je, who’s completely addicted to dopamine. Lee Jun-young’s performance feels like the webtoon character was literally brought to life.

A Name That Screams Power

Can we appreciate how sexy Seong-je’s name is? ‘Geum’ means ‘metal,’ ‘Seong’ means ‘success,’ and ‘Je’ means ‘king.’ In the original webtoon, he’s known by the nickname “Strong Tyrant,” and overseas, Seong-je’s name is “Wolf.” Even his name construction suggests this character was designed to be magnetic.

The Dopamine Addict’s Complexity

Seong-je is completely obsessed with dopamine – he plays games all day, smokes cigarettes, never puts his phone down, and fights people constantly. Being completely marinated in dopamine seems like his whole identity, but somehow it doesn’t come off as pathetic when you’re watching – it just feels natural because, well, it’s Seong-je.

And like he says, “My body’s been getting sluggish lately, so this works out perfectly” – when Baek-jin orders him to go beat up Go-tak, he’s practically thrilled because he’s been starving for that dopamine hit, though Seong-je already knows Go-tak is beneath his level – he’s fought him before and knows exactly what Go-tak’s capable of. So on that rooftop, he beats Go-tak down pretty quickly and finds himself bored again, that familiar emptiness creeping back in.

And then – boom – Si-eun just appears out of nowhere. Like the universe decided to drop this perfect new puzzle right in front of him when he needed it most.

The Rooftop Fight

The details in that rooftop fight scene are just insane. Si-eun snatching Seong-je’s glasses to use the frames as a weapon – I never saw that coming the first time I watched it. When his pen attack doesn’t work, Si-eun takes a bunch of punches from Seong-je, but he’s deliberately letting himself get hit while maneuvering Seong-je toward that corner with the flower pot.

Si-eun doesn’t react much to provocation and uses whatever’s around to make up for being physically smaller – like Woo-young said, it looks “cowardly,” or as Go-tak put it, “what a sneaky bastard.” But for Si-eun, it’s the smart choice, and watching it definitely gets your adrenaline going.

I was really impressed with Seong-je’s makeup throughout the series too. The makeup team did such a good job – his face always has bruises somewhere, which shows he doesn’t just enjoy dodging hits during fights; he actually enjoys taking them too.

The “This is it!” Moment

Seong-je’s legendary scene has to be when Si-eun takes his glasses and stabs his foot with the temple tip, and he giggles like a true psycho saying “This is it!” while continuing to fight. I got complete chills from Lee Jun-young’s acting that went beyond the insane character of Seong-je.

Si-eun looks like someone I want to beat up

The best part of Weak Hero Season 2 has to be watching Seong-je and Si-eun go at it, and just their whole dynamic together. Seong-je’s got the height advantage so he’s always looking down at Si-eun, but you can see his mouth quirk up every time Si-eun’s around. He calls him “newbie” but there’s something almost fond about it.

This pretty-faced kid actually has the nerve to stare him down with those wide eyes – totally different from everyone else! When Seong-je says “Si-eun looks like someone I want to beat up,” I get it. Si-eun is basically Seong-je’s perfect dopamine fix.

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The detail work in their first bathroom scene was so good – Seong-je picking up on Si-eun’s crazy peripheral vision, then using that against him later by blocking his sight with his palm during the rooftop fight. Really smart writing. And can we talk about Seong-je’s voice? The way he says “Your eyes look sad” to Si-eun, that lazy, soft tone he has – it’s weirdly compelling. Even the way he smokes and flicks his cigarettes away has this casual swagger. During fights, watching him dodge and move around is just satisfying to watch.

The Romantic Psycho

What makes Seong-je even more interesting is this whole romanticist thing he’s got going on. Like when he shows up because Si-eun called him, and they’re eating ramen outside the convenience store, and he just randomly brings up tetanus shots. When Si-eun says “I was sorry about that,” you can literally see Seong-je melt a little – it’s sweet and funny at the same time.

Seong-je starts leaning toward helping Si-eun, but then he pulls a complete 180 and helps Baek-jin instead. During that big Union vs. Eunjang fight, he ties Si-eun up at the bowling alley so Baek-jin can almost win.

I loved that twist. Instead of doing some predictable redemption arc where he abandons Baek-jin for Si-eun, Seong-je basically goes “nah, I’m getting too soft” and chooses to stay loyal to his bad guy identity. There’s something really cool about a character who’s self-aware enough to know who he is and stick with it, even when he could have gone the “nice guy” route.

Character Interpretation

Park Ji-hoon on Lee Jun-young:

I was really nervous when filming with Lee Jun-young in the bathroom. Lee Jun-young’s fists are incredibly fast. You could actually hear the sound of wind from his punches. Of course, we had to be tense when filming action scenes. I was nervous thinking that if I lost focus for a moment, I might really get hit. That day was Lee Jun-young’s first day of filming. After the shoot, the way he walked with his hands in his pockets really reminded me of his character Seong-je. I told him, ‘You’re really Seong-je.’ Their actual personalities are quite similar too.

In an interview, Lee Jun-young revealed:

Director Han Jun-hee told me, ‘You need to play this character Seong-je, because Seong-je is literally you,’ which is why I decided to participate. He’s actually quite similar to me. The romantic aspects of the human Lee Jun-young are also present in Seong-je.

Director Han Jun-hee even said he would have changed the character entirely if Lee Jun-young hadn’t taken the role. That’s how perfect the synchronization was.

What Season 3 Might Hold

Season 2 wraps up with Baek-jin vanishing and Seong-je clearly moving up in the world – looks like he’s heading toward something way bigger and darker than just high school gang stuff. If we get a Season 3, I’m really curious how Si-eun and Seong-je are gonna handle facing each other again.

Weak Hero Class 2 does a really solid job continuing Si-eun’s story, and both Park Ji-hoon and Lee Jun-young just killed it with their performances. The way they developed these characters, plus all the intense fight scenes and how they handled the friendship and trauma stuff – if you liked Season 1&2, you’ll definitely want to watch this.

📍 Ever wondered what would’ve happened if Su-ho never ended up in that coma – like where would his friendship with Si-eun have actually gone?