A/N: Ok, really quick please read this because it's important: this is not funny (at least not on purpose), it doesn't really fit the vibe of the story at all, but I had this thought and I had to write it so I sat down and I just spit it out in like an hour. Selukai has always been one of my absolute favorite relationships and I didn't think I was going to put it into this story, but I just had a flash and it needed to be written down. It turned out way longer than I expected and when I read it over I realized it didn't really fit the story. But I didn't want to change it to be funny or anything, I just wanted to show it to you guys the way it is. So here you go, if you don't like backstory then I'm sorry just skip this, but I do really like how it turned out so yeah. Here ya go. 

Kyungsoo wandered into the school library, taking a hesitant seat near one of the great bay windows, lucky to find an empty table. Usually he had History during this hour, but quite a few students were writing a replacement test and the teacher had told the others to use the class as a study period. Kyungsoo spread his binders carefully across the table, trying to decide which class would be the most productive. It was midterms week, before winter break, and in Kyungsoo’s eyes, each minute to study had become a precious commodity.

“Hey,” a voice interrupted him just as he had chosen Calculus, and then Sehun appeared in his view, sitting himself in the seat across.

“Hi,” Kyungsoo squeaked out in surprise. “What are you doing here?”

“Skipping,” Sehun shrugged, spreading his legs across another seat. “I hate Math.”

“…Oh,” Kyungsoo managed in response. For him, skipping seemed like a foreign concept, especially since it was clear to him that Sehun was a smart kid. But over the few months he had spent with Sehun, he had quickly realized that it was kind of hopeless to argue with him.

“Why are you here?” Sehun asked him, eyeing his colour-coded binders. “Don’t you have class?”

“The teacher gave us a spare,” Kyungsoo said. “I’m studying.”

“Ah,” Sehun nodded. “Right. Mid-terms.”

“Yup,” Kyungsoo answered awkwardly, and began to take out his pencils. He couldn’t think of anything else to say, and in the silence he opted to start taking notes, opening his Calc book to Arbitrary Constants.

“So,” Sehun said after a minute or so of watching Kyungsoo read his textbook, “You and Jongin, hey?”

Kyungsoo dropped his pencil. He fumbled for it for a moment, stuttering, and looked up to see Sehun watching him with what might have been dry amusement. “Um,” he answered once he had retrieved his pencil. “Well.”

Sehun raised an eyebrow. “Well?”

Kyungsoo bit his lip again, not sure what to say to appease him.

“You guys dating?” Sehun prompted him casually.

“No,” Kyungsoo said quickly. Sehun’s eyebrows rose again. “I mean,” Kyungsoo spluttered, “I mean, yes. Sort of. We're just not telling people. I'm sorry, I was just surprised you knew. But you're his best friend... of course he told you.”

Sehun shrugged. “Yeah, he’s told me. I just wanted to hear what you would say.”

“Oh,” Kyungsoo answered uncomfortably, biting his lip again.

“I thought it was weird that he made me promise not to tell anyone,” Sehun continued smoothly. “There a reason you guys are keeping it on the down low?”

Kyungsoo shrugged again, feeling his cheeks flush. “No- Yes-well yes, of course.” He glanced down at his hands, unable to meet Sehun’s eyes. “It’s just. Well. My parents wouldn’t be thrilled with me dating someone- I’m supposed to focus on school. And…” He paused, swallowing.

“And?” Sehun urged him.

“Um,” Kyungsoo mumbled. “You know. They wouldn’t be thrilled with me dating a…him.”

“Ah,” Sehun nodded in understanding. “I see.” They lapsed into another silence. Kyungsoo threw himself back into his problems, trying to control the flush in his cheeks.

“I would be careful,” Sehun said after a moment.

Kyungsoo looked up. “Careful of what?” he asked.

Sehun shrugged. “Keeping things casual. It never ends well.”

Kyungsoo swallowed. “Okay.” He turned back to his binder.

“Kyungsoo,” Sehun said, and his voice had suddenly gone soft. “I mean it.”

“Why do you care so much?” Kyungsoo demanded sharply. He kind of wished Sehun would leave. He had to study.

“You like him a lot, I can tell,” Sehun said, unfazed. “And Jongin likes you a lot too. For his sake- for yours too- I just don’t want it to end badly.”

“You don’t know that it will,” Kyungsoo said.

Sehun shrugged. “I’ve been there, that’s all I’m saying.”

Kyungsoo glanced at him in surprise. He eyed Sehun again, his body spread languidly out in arrogant seductive grace. Everything about him- from the fading hickeys on his collarbone he had barely tried to cover, to the tousled mass of I just had  styled hair, to the corner of a packet poking out of his tight jeans- it all screamed  me and leave me, I don’t give a because I’ll probably leave first. Kyungsoo couldn’t imagine Sehun actually liking someone, let alone him actually caring enough to be hurt. “Is that so,” he finally managed to say, and carefully put down his pencil. “Someone broke your heart?”

Sehun smiled wanly. “Two people. It’s okay though. We’re still friends.”

Kyungsoo raised an eyebrow. “Do I…know them?”

Sehun nodded with a shrew smile. “You’re dating one of them.”

“What?” Kyungsoo gasped, unable to contain himself. He stopped, waiting for Sehun to say Just kidding! But of course he didn’t. “Jongin? And you?”

Sehun laughed. “Nah. I mean, I’ve hooked up with him before, but that was before we really knew each other. No. It’s not what you think. It’s a little more…” he paused, his mouth twisting downward, “…complicated.”

“Care to explain?” Kyungsoo asked dryly. He sounded much calmer than he felt, his mind whirling at the thought of Jongin in bed with- nope, he didn’t even want to think about it. Not even a little bit.

“Sure,” Sehun answered. “It’s not like it matters now anyway.” He took his feet off the chair, sitting up properly and leaning in casually towards Kyungsoo. “So, me and Luhan used to be a thing.”

“What?” Kyungsoo spluttered, again unable to stop himself. Sehun gave him a look. “I mean…okay. Cool. Go on,” he managed, head spinning.

“A thing,” Sehun continued smoothly, his face blank. “But not dating. Because he didn’t want anything serious, and I liked him, so it was whatever. I would’ve accepted anything he said, as long as we hung out and ed.” He paused, fingers twitching. “So we weren’t serious. No one even really knew. And Luhan- see, he was a party animal, so he would go out to parties all the time, and sometimes I’d hear stories- he kissed this guy, this other guy felt him up, whatever.” He stopped again, looking down at his hands. “I didn’t really listen. And I believed him when he said it wasn’t true, because I liked him and I- I never saw it myself because I never went to parties. I wasn’t into that stuff.” He smiled wryly, and looked back up at Kyungsoo. “I was like you. I cared so much about school, I’d never go out and drink and myself up like that.”

Kyungsoo took this in, his hand tightening over his pencil to keep himself from not screaming. Sehun? Not into partying? Into…studying? Yet he managed to refrain himself from yelling, and Sehun continued.

“Anyway, one time I thought I should go. Just to experience it, you know? So I did. And it was fun, it was chill. Until,” he stopped, his lips, and at the edge of the next sentence Kyungsoo could hear his voice crack.   “Until I walked in on Luhan blowing Jongin.”

At this Kyungsoo audibly gasped. His pencil dropped from his hand again.

“Jongin was my best friend at the time,” Sehun continued, fast and stormy now, his eyes downcast. “But I didn’t tell him how much I liked Luhan, because Lu told me to keep it quiet, and I did, I listened to him. I didn’t tell anyone. As far as Jongin knew we just hooked up occasionally…which I guess in the end…was all it was. But I did like him, I liked him a lot, Kyungsoo. I believed him.” He stopped to breathe again, and Kyungsoo just looked at him, a million things making sense at once. When he spoke again, Sehun looked back up at Kyungsoo, and he saw that his face was blank again. “So I stopped talking to both of them for a while, and they figured out on their own that they hurt me. I couldn’t talk to Jongin without wanting to hit him so I needed another friend- Tao and I became close, so that was good I guess, but then he started dating Kris and it too much to see them together. By that time it had been a couple months, so Jongin and I were sort of okay again.” He leaned back, folding his arms across his chest. “That was last year. Funny thing, after that, Luhan stopped drinking and partying almost completely. And he started dating Minseok. Minseok, who was insistent on something serious, who hates parties as much as I did. Except it’s not a problem for them. Not now.”

Kyungsoo stared at him, everything crashing down into understanding. So this was why Sehun was so flighty, sleeping with whatever walked on two legs and would have him. This was why he was at a party every weekend, drinking away, not giving half a damn about his schoolwork. It was all because some pretty boy had shattered his heart. And it had ruined him.

Kyungsoo wondered if Sehun saw the irony that he had basically turned into the person who had hurt him.

For a while they just sat there, opposite of each other, and then Sehun stood abruptly.   “I should get back to class,” he told Kyungsoo. “I left my bag.” And with that he was strolling away, leaving Kyungsoo behind to study in peace.