Day Thirteen. 9:17 AM.

Myungsoo sat in his chair, staring down at his case notes. To outsiders, it might have seemed as if he were immersed in his work, concentrating on doing his part in the investigation. But if they were to take a closer look, they would have noticed the dark shadows beneath his eyes. They would have seen the paler-than-usual pallor of his skin. And above all, they most certainly would not have missed the blank, albeit exhausted look on his face.

Simply put, the man was tired. It had been another insomniac night for him. When his alarm clock had dutifully rang at its usual time, Myungsoo had been sorely tempted to call in sick for the day. After all, he was still a growing man. He needed his sleep. All work and no rest makes for a very bad Myunggie, Woohyun would have said.

But Woohyun wasn't  there. And Myungsoo was a CSI agent. His team was already behind on catching a dangerous and possibly insane murderer. So, as much as he would have loved to doze off, Myungsoo forced himself to pay attention to what Sungjong was saying.

"- best if we review her profile. That way, we can refresh our memories and think of new theories regarding her death. Are you guys okay with that?"

"Sure," Myungsoo mumbled, resisting the urge to yawn. He couldn't help but wonder if he was the only one who felt the tension in the room. There was Sungjong, who was acting like absolutely nothing had happened between them. Had he forgotten about the kiss already?  And sitting beside Myungsoo was Sungyeol, who hadn't spoken to him since he'd basically told the ravenet to get out of his life and mind his own business. Which had happened yesterday. Time sure did pass by slowly in annoyingly dramatic situations, didn't it?

The inspector cleared his throat. "Yeah, that sounds like a good plan. But let's try to finish as soon as we can. We don't have any time to waste."

Sungyeol, ever the silent guy, said nothing.

"Alright, then." Sungjong opened his notebook. The three agents were currently in Conference Room Eleven, seated in the chairs closest to the whiteboard. The slender man had proposed holding a quick debriefing there rather than at their desks, where it was sure to be noisier. "Lee Minhee. A graduating university student. The third and most gruesomely killed victim. In my opinion, she's the most obscure case out of them all."

Myungsoo nodded and straightened his spine. "Agreed. Besides her family history and school life, not much is known about her." Out of the corner of his eye, he saw Sungyeol slowly turn towards his direction. Myungsoo tried to ignore the way his gaze seemed to burn the side of his head. "Orphaned, living alone, and pursuing an interior designing career. Why would the Mockingbird possibly want to kill someone like her?"

"You forgot to mention Kwon Changsun."

Myungsoo stiffened at his companion's comment. "I didn't forget about him," he replied, doing his best not to let his tense feelings show. A swirl of emotions rose inside of him, triggered by the sound of Sungyeol's voice. A part of him wanted so badly to see what was behind Sungyeol's walls, but another part wanted to punch him in the face. So now that he had told Myungsoo to stay away from him, Sungyeol was going to act as the antagonistic voice of his conscience?

Turning his head, Myungsoo gave the newcomer a hard stare. "I remember everything Chen told us about Kwon Changsun. Don't underestimate me."

Sungyeol returned his stare with a cool gaze of his own. "I never said you forgot about him. I said you neglected to mention him. There's a difference between the two."

"Okay, so I didn't mention Changsun." By now, the urge to cause bodily harm to Sungyeol was overshadowing the determination to see into his heart. Myungsoo forgot all about his tiredness as he narrowed his eyes at the rookie. "But why should I? We all know he loved Minhee. We know he was a violent, hot-tempered man. But we also know he isn't the killer. He's already crossed off the suspect list. Why should I bring him up?"

"I was under the impression we were going over the girl's profile. Should he not be included in the review?"

"Maybe I was going to talk about him later on. This is why you shouldn't cut in when other people are talking. There are a lot of things you lecture me on, newbie, but you could learn a few things yourself-"

"Okay, enough!" Sungjong intervened. He had been watching his partners' spat with a startled expression, as if he'd just realized the high amount of tension in the air. "What's gotten into the two of you? Why are you so hostile all of the sudden?"

Myungsoo felt like scoffing at his words. All of a sudden?  What, so Sungjong hadn't noticed the strain their relationship was going through in the past few days? "Forget it. It's nothing."

"Well, it doesn't seem like nothing," Sungjong fired back. "You don't just come to work and pick fights for no reason, you know."

You do if it's Lee Sungyeol. Taking a deep breath, the dark-haired male tried to restrain his outburst. He saw that the newcomer had resumed staring at the whiteboard, unbothered as ever. For some reason, seeing his emotionless face irritated Myungsoo all over again.

But instead of displaying his anger, Myungsoo picked his pen off of the table. "Look, I told you. It's nothing. Nobody's fighting here, Sungjong. Let's just leave it and get on with our work."

Sungjong gazed at him with a sharp expression. He looked annoyed, like he wanted to argue back, but Myungsoo knew better. Behind his irritation, there was a tiny bit of hurt flashing in his eyes. As if he couldn't believe Myungsoo wasn't trusting him, his best friend since childhood, to talk about his feelings. "... Fine," he said after a moment. "If that's what you want. What about you, Sungyeol? Are you okay?"

"... hn."

Myungsoo ignored the man beside him as he continued with the debriefing. "So. Back to Minhee's past. Let's start with her family history. She was the only daughter of Lee Jonghyun and Lee Yura, who passed away around twenty years ago. The details are vague, but apparently they'd been involved in a work accident."

"The Institution for Higher Living," Sungjong said, avoiding looking directly at Myungsoo. "That's where they worked. It's that medical laboratory in the outskirts of Seoul. There was a gas leak in the lab they were working in, which caused theirs and six other employees' deaths. Thoughts, Sungyeol?"

A minute passed before his question was answered.

"While her family history is fascinating," Sungyeol responded in his bored voice, "I'm more interested in what the pastor said. According to him, she wanted to 'atone for their sins.' Does that not sound like a possible link to the killer?"

"Oh, right!" Sungjong rifled through his notes. "I forgot about what the pastor told us. It was more like a passing statement, so he never expanded on it- Ah, here it is. 'Prayed to atone for parents' sins.' You have a good memory, Sungyeol.

"I think this could be a really big lead," the younger man continued. "I mean, even if her parents' criminal records are clean, there could be something that they've hidden. Whatever sins they committed must have been bad if Minhee insisted on making amends for them, two decades after their deaths. I'll go check this out today. Actually, I think I'll leave right now."

"Are you going to visit the chapel again?" asked Myungsoo. Besides the awkwardness hanging between them, he couldn't help but feel a bit bemused at the quick turn of events. 

"Yeah." His friend gathered up his belongings. "He's the one who gave us this lead, after all. Maybe Minhee told him about whatever her parents did, and he just forgot on the day we interviewed him."

"Makes sense." Myungsoo nodded. "I'll... call you if we need you for anything."

Sungjong smiled lightly. "Doesn't mean I'll actually come," he joked, but the subtle look of hurt was still there. "Work hard. See you later, Sungyeol."

The newcomer acknowledged his departure with a jerk of his head. "Remember to ask about the atonement process. What her parents did was important, but we also need to know how the girl plays into it."

Sungjong shot him a quizzical glance, but didn't question his advice. He gave one last nod of farewell to his partners, before pulling the door shut behind him.

Myungsoo waited until the door had fully closed before initiating more conversation. "I guess we'd better go, too. Sunggyu told me to search through Minhee's apartment again today. Said there might be something we missed the first few times." Picking up his notebook, the agent rose out of his conference chair.

"Come on, Sungyeol. Let's go."

A pair of dark, unreadable eyes pierced into his own. "I thought I told you to stop acting friendly with me."

'Seriously? You're starting this again?'  Normally, Myungsoo was very good at keeping his temper in check. But in just one single morning, Lee Sungyeol had managed to flare it up and set it to the explosives-level more times than he could count. "You did, but that doesn't mean I'm going to listen to you."

Sungyeol gazed at him. His face was impassive, but Myungsoo could have sworn he saw something flit across his eyes. "You would do well to listen to offered warnings. Ignoring them can be a dangerous habit for a crime scene investigator." He stood up from his seat. Not bothering to gather his notes, Sungyeol walked closer until he was right in front of his senior agent.

"How many times do I have to warn you, Kim Myungsoo?" His expression was as unreadable as ever, but Myungsoo could hear the slight edge in his voice. Was this it? Perhaps the time had come for Sungyeol's mask to finally crack off. "I'm not here to make friends. Sorry to say, but that includes you. I don't want anything to do with you. I'll keep telling you again and again if that's what it takes-"

"- and now I'm  telling you, Lee Sungyeol," Myungsoo interrupted. "I don't care about what you say." He was quite surprised with himself that he had spoken up against the newcomer. Where had that come from? Was it his anger talking, taking advantage of the heat of the moment? Or was it a feeling that ran much deeper, having longed to burst free ever since their first meeting?

Shaking the thoughts out of his head, Myungsoo took a step closer to Sungyeol. "I'm not going to listen to you anymore. I'm tired of hearing how you're 'not here for friends' or 'don't want anything to do with others.' You may hate us, you may want us out of your life, but guess what? You're stuck with us. You're stuck with me. So get that through your thick skull and accept the way things are, newbie. Because I'm sick of the headaches I get whenever I think about you. You got that?"

Sungyeol blinked at him. Then, with slow, deliberate movements, he made as if to walk out of the room. "You're too persistent for your own good-"

"Maybe I am!" Without thinking, Myungsoo grabbed hold of Sungyeol's wrist. Irritation egged him on as he leaned in closer, moving until his face was right in front of the newcomer's. From this close of a proximity, Myungsoo could see the finer details that made up Sungyeol's features- the smoothness of his skin, the curve of his cheekbones, and the long lashes that framed his guarded eyes. He resisted the impulse to touch Sungyeol's face. Instead, he narrowed his eyes and continued with his earlier speech.

"Shut up and listen to me for once, alright? I don't know what happened to make you change all of a sudden, but I don't like it. And yeah, I've only known you for half a month, but that was enough time to figure out you're hiding something inside of you." Subconsciously, Myungsoo softened his voice. "I know that it's something painful. A secret that hurts so much, you're willing to give up everything else to avoid the pain. But what you don't know is, that only makes it worse. Running away and hiding makes things so much more worse in the end."

Sungyeol flickered his eyes at him. "... Why do you care so much? I already said it isn't any of your concern."

The ravenet stared back. As he studied the expressionless man before him, realization dawned in his mind: he didn't  know. That was to say, he knew, but he wasn't quite sure as to how he could word it. It was complicated. As a person who had to be kissed to understand someone else's feelings for him, Myungsoo wasn't good at sentimental matters. He'd always preferred leaving it to Hallmark cards to get the message across during holidays.

Dear (insert friend's name here), Merry Christmas! May the holidays bring the same kind of joy you have brought to me in our years together. Love, (insert your name here).

But, seeing as there were no pre-made greeting cards around, it was up to Myungsoo to make Sungyeol understand once and for all.

"To be honest, I don't really know." Myungsoo was aware that he was still holding onto the younger man's wrist. A voice in his head told him to let go, but instead, he found himself tightening his grip. "At first, I found you bothersome. You were rude, frustrating, and everything you did pissed the hell out of me. Actually, you still annoy me today, but that's not the point. What I'm trying to say is, you're right. I shouldn't be caring for a guy like you. But... For some reason, I feel like I have to. Like I'm meant to do this. Something's holding you back from being your true self, Lee Sungyeol. I'm determined to figure out why."

His little confession was met with... silence. No response. On the wall above the doorway, a clock ticked time away, making Myungsoo all-too conscious of Sungyeol's lack of an answer. As reality sunk in, he began to regret everything that had spilled from his lips. Really, Myungsoo? "Accept me because I hate the headaches you give me?" What other brilliant confessions will you come up with next-

Bzzz, bzzz. Bzzz, bzzz.

The vibration of his cellphone jolted Myungsoo back to attention. Feeling slightly flustered, he released Sungyeol's arm to answer the buzzing device in his pocket. "... Hello, Kim Myungsoo speaking... Wait, what? You did? No, we're still at HQ. Yeah. Alright. Relax, we're on our way." 

He hung up on whoever it was who'd called him, and addressed his still-quiet companion. "That was Sungjong," he said, looking at the spot over Sungyeol's shoulders. "He found something at the chapel that he thinks we should see. I told him we'd be there ASAP." Without waiting for an answer, he began making his way towards the door.

Just as his hand had turned the silver doorknob, Myungsoo heard the rustle of movement behind him. He glanced back to see Sungyeol gathering his notes in one fluid motion. After he had everything in his grip, he then turned around and walked to where Myungsoo was at the doorway.

"What are you standing there for?" he asked in his apathetic voice. "Move. You're wasting time." He proceeded to brush past the surprised-looking agent, not bothering to apologize for his brusqueness or give his delayed response to their conversation before.

But as Sungyeol passed by Myungsoo, the agent could have sworn he gave a low sigh of defeat under his breath.

"You stubborn fool."

------------

"Man, I knew there was a reason why I always skipped biology in high school."

Woohyun eyed the notes spread out in front of him. They covered the entire desk he was working at, filling his vision with messy equations that looked too complicated to follow. Heaving a sigh, the agent ran his fingers through his carefully-styled hair. "Yup. Bio, chemistry, physics, you name it. That was just not for me."

"I know," Sunggyu's voice dryly commented. Woohyun turned his head to look at the Bossman, who was pulling out a few files from his cabinet. "I was your lab partner for all three classes, remember? It was such a pain covering for you and doing the reports by myself."

Woohyun grinned. "Oh, don't worry. I remember. You're still the same nagging grandpa that you were all those years ago."

Sunggyu shot him a glare as he walked back to his desk. Incidentally, it was the same desk which Woohyun had decided to dump all of the research notes onto. That would soon prove to be a problem, seeing as the Seoul branch leader had a pile of paperwork to get started on himself. "Remind me again why you're in my  office working at my  desk?"

"Come on, Gyu." The lazy inspector threw a smirk in his direction. "You're always saying how intellectually talented you are. I think it's time you put down the paperwork and used that brain of yours for more productive matters. Like helping me, for one."

Rolling his eyes, Sunggyu plopped down in his office chair. "Why do I even put up with you?" he asked, but it was mostly to himself. Sighing, he reached out and picked up one of the notebooks. The sooner he helped Woohyun with this, the sooner he could finish his other work. "I swear, I should just fire you and get you out of my hair already. Maybe transfer you to another branch if I'm feeling nice."

"Nah, you wouldn't do that. You'd miss me too much."

Sunggyu scoffed at his friend's overconfidence, but chose not to reply. Instead, he flipped through the worn-out book in his hands. "So you and Chanyeol found all of this yesterday, right? When you went to search that hidden room in Lee Seonwoong's house?"

"Yeah." Woohyun sat up straighter. "There were a ton of other packages filled with lab slides and equipment. I think we went through more than sixty of them. But this stuff here-" he gestured at the desk- "is from that one box I told you about. The one marked with the Mockingbird picture. These aren't all of the notes, but I tried picking out the most important-looking ones for you to see."

"A picture of a mockingbird... Well, if you're looking for an expert's opinion, I'm sorry to say you have the wrong person." Sunggyu frowned at the notes he was holding. "It's been so long since I looked at anything chemistry-related. I mean, CM = ECW26 + ICW4 + F19?  What do these letters stand for, again?"

"You're asking me?"  With a shake of his head, Woohyun grabbed a notebook of his own to thumb through. "Maybe we should call Youngjae down. I sent him an email about this yesterday, but he hasn't replied back yet."

"No, leave him be," Sunggyu replied a bit absentmindedly. His concentration and interest in the papers were beginning to grow. "He's busy investigating a lead on the mockingbirds. Apparently, it led them to a major drug operation near the shipping docks last night."

The dark-haired inspector turned a page. "On Highwater Street, right? I heard about it when I came in this morning. Too bad I wasn't there; it sounded like a lot of fun. Anyway, back to these notes!" Woohyun tossed his book down and glanced at his friend.

"What's the connection between these notes and our guy?"

Sunggyu didn't have to ask who our guy  was. From his time and experience with Woohyun, he'd learned that the narcissistic agent preferred calling their targets our guy  or our buddy, rather than the generic killer. According to him, it made everything sound much less foreboding at work. "I don't know. What makes you sure we can even link them together in the first place?"

"That's the thing." Woohyun furrowed his brows. "I'm not  sure. There's a big chance this is all a coincidence- just another accidental red herring to throw us off track. But think about it. A murderer shows up out of the blue and starts killing people who have nothing to do with each other. He uses mockingbirds as his symbol. Then we find that one of his victims has a box, a box that's been labelled with the very same bird. I mean, isn't that enough to at least make you curious?"

"... Yes," Sunggyu admitted, glancing up from his folder. "It is. And when did you become so perceptive with these things? You're not normally like this during investigations."

Woohyun smiled, but carried on with his earlier speech. "From here, the obvious next step would be to decipher these notes for our understanding. There are two main parties I thought of who can help us do this: Lee Seonwoong's daughter, Jangmi, and the research company he used to work for.

"I already called them both," the inspector continued. "I phoned Jangmi yesterday to see what she knew about the mockingbird box. But she had no clue about it. Everything I told her was completely new information."

"And the company? What did they know?"

"About as much as Jangmi did." Woohyun stretched out his arms, grimacing as he worked out the kinks in his muscles. "They're a research institution, right? So luckily for us, they had all of their projects saved in their filing system. That's including the ones Seonwoong worked on back when he was there, which was about fifteen or so years ago. But nothing in their files matched what we found in the box."

Glancing at his companion, Woohyun added, "That's where Chanyeol is now, actually. The secretary we talked to told us they had no idea what the mockingbird could mean, but he insisted on searching through their records himself. Said there was a chance they could have missed something."

"Huh." Sunggyu blinked. "I didn't know Chanyeol could be so... thorough."

"I don't think any of us did," Woohyun chuckled. Grabbing a different notebook, his expression turned serious once again. "Come on, help me look through this stuff. There has to be something  that can help us."

The CSI leader cast one last skeptical look at his desk. Was there really a clue hidden in Seonwoong's notes that could help them solve the Mockingbird case? Nonetheless, despite the shadow of doubt clouding his mind, Sunggyu resumed with his reading. "Fine. I'll help you, since you seem so determined about this. But I'm kicking you out after half an hour. I can't neglect my branch duties forever."

He was rewarded with another little smile from the agent. "That's fine," Woohyun said simply. "Thanks, Gyu."

"Hmph... Don't mention it."

Neither of them spoke again as they studied the notebooks. It was puzzling, Sunggyu thought to himself, scanning the pages with an eagle eye. Puzzling, and definitely a headache to read through. All he could see were long and detailed equations, giving no hint as to what purpose they served. What were these formulas about? Why had Seonwoong filled up a whole box with seemingly useless research? As intellectually gifted as he was, Sunggyu had to admit even he was stumped.

Frowning, Sunggyu turned the page. It was blank. He had reached the end of the book. Putting it aside from the others, the branch leader picked up a different one from his desk. He was in the middle of opening it when Woohyun decided to break the silence of the room. "Did you find anything yet?"

"No," Sunggyu answered, glancing down. "No, not yet..." His voice trailed off when he saw what was written there.

"Hold on. I think I got something."

"Really? What is it?" Woohyun immediately peered at the notebook in his friend's hands.

Sunggyu tilted the book so they could both read it. The page he was on had been titled with large, capitalized words: CASE 21: PROJECT MOCKINGBIRD. Underneath the title, an extensive list of chemicals and compounds appeared.

H2O 35, C 20, NH3 4, CaO 1.5...

"What the hell could this mean..." Woohyun muttered. Squinting at the page, he let out what sounded like a frustrated sigh. "Well, that solves the mystery of the bird. Now we know why the box was labelled with a mockingbird. But still, nothing's making sense to me. Maybe you were right, Gyu. It doesn't look like any of this is gonna help us out."

"Maybe..." Sunggyu was still studying his set of cryptic notes. Something about this particular bunch seemed vaguely familiar to him. He racked his brain in search of the answer. These formulas, these chemicals; Sunggyu could have sworn he saw them somewhere before. It was one of those annoying moments where he wanted so badly to remember something, but his failure of a memory wouldn't allow it.

He decided to take a chance and ask Woohyun for help.

"Hey, look at this." He pushed the book towards his defeated companion. "Read the stuff underneath the first few lines. Doesn't it seem familiar to you?"

The agent took a moment to study the page. "... You're right," he said slowly, as if he too were trying to drag his memory out. "It does. That's so weird. I thought I forgot everything I learned in high school, but I actually remember something about this."

"Really? What do you remember?" Sunggyu leaned in closer.

Woohyun snickered. "Well, for one, the day we learned about this was the day you tripped on your way to your desk. You were handing in your report and probably stumbled over your own clumsiness, because the next thing we knew, you were sprawled out on the floor with your face flat against the ground."

Sunggyu glared at him. "I meant, do you remember anything useful. Please keep in mind that we're short on time, and bringing up embarrassing stories of me is just giving the killer more time to escape."

"Okay, okay. Sorry, Gyu. But you have to admit, it was pretty funny at the time." Woohyun grinned at him cheekily, then continued with his trip down the memory lane. "So, the lesson. I don't remember all of the details, but I think- no, I'm sure- it had to do with body composition. You know, what makes up body mass, the chemical ratio, and so on. It was actually kind of interesting, which is why I didn't forget it along with the other bio lessons."

"You're right." While Woohyun had been chatting, Sunggyu had resumed reading over the notes. "The lecture afterwards was one of the longest we had to listen to in that course... Anyways, body composition? What's this all about? What exactly did Seonwoong intend to accomplish with- what did he name it- Case 21?"

"That's what we need to find out." The younger man leaned back in his seat. With his hands on the back of his head, he wore a thoughtful expression to replace his previous grimace. "Body composition... How can we link that to our guy now? I'll have to call Chanyeol and tell him about this stuff. Hopefully, he's still at the institution, but knowing him, he probably gave up after the first twenty minutes-"

Brring. Brrring.

The shrill cry of the telephone cut through Woohyun's speech. Raising a brow, Sunggyu shrugged at him before answering the receiver. What was this now? He hadn't been expecting a call from anybody.

"Hello, Kim Sunggyu's office. Can I help you with anything?"

Woohyun waited for his friend to finish with his call. His gaze slid back to the open notebook, still bemused with their little discovery.

"Yes. Yes, that's right. I sent out alerts on the day of the first murder. That was a bit over two weeks ago, I believe..."

Could the formulas really have something to do with the Mockingbird Killer? It was all quite a big stretch, if one thought about it. There was the possibility of the killer having wanted the research to himself, inciting him to murder Lee Seonwoong. But why kill the other victims, as well? Son Taehyun and Lee Minhee didn't have any connection to the old man. And if it was the notes he'd been after, why hadn't the murderer taken them from Seonwoong's house-

"Wait, what?  Can you repeat that? Uh-huh... Yes... I don't believe this. No, you must be mistaken. Are you sure it's him?"

Distracted from his thinking, the inspector shot his boss an inquiring look. Sunggyu only ignored it, however, too preoccupied with his call to appease his curiosity.

"Yes... Yes, that's right... I still don't believe- No, that's not it. It's just that it's been over two weeks now. We'd started to think he'd left the country or something. Anyway, please send us all of the information as soon as possible. I'll call you again later to discuss the matter. Thank you for informing us."

"What was that about?"  Woohyun opened his mouth to ask, but it wasn't necessary. As soon as Sunggyu replaced the receiver on the machine, he turned to face his companion.

"That was the Yangsan CSI station," he began, voice low and tense. "They had some news which I think everyone here will find very interesting."

"What? What is it?" Woohyun demanded. Seriously, all of this suspense was just killing him. Narrowing his eyes, he scrutinized Sunggyu's face in search of an answer. When his friend finally responded back, Woohyun understood the edgy, slightly anxious note in his expression.

"They found the body of a dead woman in a park last night. She had a bird placed in her right hand. The Mockingbird Killer... He's finally struck again."

[A/N]  I'm not satisfied at all with the Myungyeol scene.. /sigh/ Here's to my lack of experience with dramatic confrontations. But do you remember that equation Sunggyu read aloud? CM = ECW26 + ICW4 + F19? I just made this equation up, but it actually has a hidden meaning behind it. I will give a huge round of applause to anyone who can figure it out.

Also, I posted the Woogyu spinoff! It's very loosely-based on this, but it tells the story of how Woohyun and Sunggyu came to be the good (?) friends they are today. I think you'll be surprised, because the Woohyun here and the Woohyun in that story are two very different people. Here's the link if you're interested -> The Tin Man and the Lion.

Thanks for reading/ subscribing/ commenting! ❤