The air in the lecture hall felt stagnant, a heavy mix of afternoon humidity and the collective anxiety of eighty students waiting for the "Big Reveal." On the chalkboard, Professor Choi had written three words in massive, blocky letters: SYSTEM ARCHITECTURE PROJECT.
In the CSE department, this wasn't just an assignment. It was a rite of passage. It was the project that separated the hobbyists from the engineers.
"I've finalized the groups," Professor Choi announced, his voice cutting through the nervous whispers. "In the professional world, you don't choose your colleagues. You work with the hands you're dealt. This is a large-scale project, so we are forming 'Major Units' of seven, which will then be divided into two 'Sub-Units' to handle different layers of the system."
Beside me, Jiyoon gripped her pen so hard her knuckles turned white. "Please don't let me be with Jisoo," she whispered. "I can't handle the flirting while I'm trying to compile code."
I didn't answer. My eyes were fixed on Hanbin, who sat two rows ahead. He looked like a statue—shoulders squared, eyes forward, completely unreadable. Ever since the holiday, there was this strange, magnetic tension between us. I still hadn't told him I knew it was his family's food on my desk, but the way he looked at me—or rather, the way he didn't look at me while staying so close—said everything.
"Group Four," the Professor called out. "Major Unit: Jeon Hanbin, Kim Jeonghan, Park Danoh, Park Jiyoon, Jeong Jisoo, Shin Sunho, and... Jung Kai."
A cold shiver raced down my spine.
Jung Kai.
The name felt like a physical weight on my chest. I hadn't seen him properly since that night. I had seen him from a distance, wrapped in bandages, looking like he'd been through a meat grinder. The rumor mill said he'd been mugged or gotten into a debt-related fight, but no one knew for sure. All we knew was that the loud, predatory senior who used to roam the hallways was now a ghost of his former self.
I felt a hand on my shoulder. It was warm and steady.
"Don't worry, Danoh-ya. I'm in your unit," Sunho-sunbae said, leaning over from the row behind. He smiled, that perfect, radiant sunbae smile that usually made me feel safe. "I'll make sure the workload is balanced."
I nodded weakly, but my gaze drifted back to Hanbin.
The moment Kai's name was called, I saw Hanbin's posture change. It was subtle—a slight tightening of his jaw, a microscopic narrowing of his eyes. He didn't turn around. He didn't move. But the aura radiating from him suddenly turned icy, like a winter storm hitting the room.
"Now, for the Sub-Units," Professor Choi continued. "Sub-Unit A, handling the Front-End and Interface: Shin Sunho, Park Danoh, and Park Jiyoon."
Sunho let out a satisfied hum. "A good team. We'll be efficient."
"Sub-Unit B, handling the Core Engine and Security: Jeon Hanbin, Kim Jeonghan, Jeong Jisoo, and Jung Kai."
The silence that followed in our corner of the room was deafening.
I watched Hanbin. He slowly closed his notebook. The "click" of the latch sounded like a gunshot. Beside him, Jeonghan—usually the life of the party—wasn't laughing. He was looking at Hanbin with a concerned, sharp expression, his usual playfulness replaced by a defensive alertness.
Then, there was Kai.
He had entered the room late, slinking into a seat in the back. He looked pathetic. His arm was out of the sling, but he moved stiffly. The most jarring thing, however, was his eyes. When the groups were announced, he looked at the list, then his eyes landed on Hanbin's back.
He didn't look angry. He didn't look like he wanted revenge.
He looked terrified.
He flinched, his entire body jerking back as if he'd been struck. He immediately looked down at his feet, his shoulders hunched, his hands trembling. It was the look of a man who had seen a monster and realized he was trapped in a cage with it.
"Let's gather in our units," the Professor commanded.
We moved to the large circular tables at the back of the hall. I walked slowly, my leg still a bit stiff. Sunho walked beside me, carrying my heavy textbook for me—another "caring" gesture that I noticed Hanbin watching from the corner of his eye.
As we sat down, the atmosphere was thick with unspoken poison.
Sunho took charge, his voice smooth and professional. "Okay, as the senior here, I'll coordinate. Sub-Unit A, we'll meet in the library tomorrow. Danoh, Jiyoon, you two are great with logic, so we'll focus on the user experience."
"And what about us?" Jisoo asked, twirling a lock of her hair and leaning toward Hanbin. She was wearing a perfume that was far too strong for a lab setting. "Hanbin-ssi, you're the lead for the core engine, right? You'll have to teach me everything."
Hanbin didn't even look at her. He was staring straight at Jung Kai.
Kai was sitting as far away from Hanbin as the table allowed. He wouldn't look up. He was sweating—visible beads of perspiration rolling down his forehead despite the air conditioning.
"Kai-sunbae," Jeonghan said, his voice uncharacteristically sharp. "You're a senior. You've done this before. I assume you'll be handling the documentation?"
Kai jumped at the sound of his name. "Y-yes. Anything. I'll do whatever. Just... just tell me what to do."
His voice was thin, reedy. I stared at him, confused. This was the man who had chased me? The man who had made me bleed? Why was he acting like he was on death row?
I glanced at Hanbin. He was resting his chin on his hand, his eyes fixed on Kai with a cold, predatory stillness. He wasn't saying a word. He didn't have to. His silence was doing more damage than any shout could.
"Hanbin?" I whispered, reaching out to lightly touch the sleeve of his jacket.
The change was instantaneous. The ice in his eyes shattered. He turned to me, and for a fleeting second, I saw it—the raw, jagged trauma and rage he was hiding behind his mask. But then, he blinked, and the "Shadow" returned, softened only for me.
"I'm fine," he said. But his voice was tight, strained.
"Group B seems a bit... intense," Jiyoon whispered to me, leaning in. "Why is Kai acting like Hanbin is going to murder him right here in the classroom?"
I didn't have an answer.
"Okay!" Sunho said, clapping his hands together, trying to break the tension. "Sub-Unit A, let's head to the café to start the wireframes. Danoh, ready?"
"Actually," Hanbin said, his voice cutting through Sunho's like a blade. He didn't look at Sunho. He looked at me. "The core engine needs the interface specs first. Danoh should stay with Sub-Unit B for the first hour."
Sunho's smile didn't fade, but it grew tighter. "Hanbin-ah, the Professor was quite clear about the divisions. I can relay the specs to you later."
"I want to hear them from the source," Hanbin replied. He shifted his chair just an inch closer to mine, a subtle claim of territory.
The two "best students" stared at each other. Sunho, the golden sunbae, and Hanbin, the dark genius. It was a battle of wills that made my heart race.
"It's okay, Sunho-sunbae," I said, trying to play peacemaker. "I'll stay for a bit and then meet you and Jiyoon."
Sunho hesitated, then nodded gracefully. "Of course. Don't work too hard, Danoh-ya."
As Sunho and Jiyoon moved to another table, the air at our table shifted again. Jisoo was trying to get Hanbin's attention, Jeonghan was watching Hanbin with a worried frown, and Kai... Kai looked like he was about to faint.
"Documentation," Hanbin said, his voice dropping to that low, guttural rasp I'd heard only once before. He was looking at Kai. "If there is a single error in the logs... if one comma is out of place... you'll redo the entire year's worth of work. Do you understand?"
Kai nodded frantically, his head bobbing like a toy. "Yes. Yes, Hanbin. I'll be careful. I promise. I'll be so careful."
I watched them, my heart heavy with questions I didn't know how to ask. I looked at Hanbin's knuckles—they were healed now, but the memory of them stayed with me.
Why was he so angry? Why was he protecting me with such violence, even when he was just sitting still?
"Hanbin," I said softly, under the cover of Jisoo's constant chattering to Jeonghan. "Are you really okay?"
He looked at me. The darkness stayed in his eyes, but he reached out under the table and briefly, so quickly I almost missed it, he brushed his thumb against the back of my hand.
"As long as you're in Sub-Unit A," he whispered, "I'll be fine."
I didn't understand what he meant then. I didn't know that he had specifically let Sunho take me into the "safe" unit so he could keep the "poison" of Kai in his own circle, where he could watch him. Where he could crush him if he ever moved again.
Hanbin was taking the trauma for me. He was sitting with the monster so I wouldn't have to.
I sat there, opening my laptop, but my eyes kept drifting to the boy beside me. He was a mystery of code and shadows, a protector who didn't want thanks, only safety. And as the project began, I realized that this semester wasn't just about system architecture.
It was about survival. And I was beginning to realize that Hanbin was the only reason I was surviving at all.