Dumb college boys AU, inspired by HIMYM's Barney/Robin. Slight Arumika.

For as long as Armin could remember, he was always mistaken for the innocent type.

While his friends went out partying, he stayed home to study. While his friends ditched class, he stayed overtime to help his teacher clean up. While his friends hooked up with girls every week, he'd volunteer at the animal shelter. So, of course, they always just assumed that he was pure, unadulterated.

Armin didn't mind it at all. In fact, he enjoyed just listening to the stories they brought home. He'd rather stay in the comfort of his own home than drown in sweaty bodies and loud music, and at the end of the day, he would rather hear about the "fun" they have than experience it for himself.

Tonight was no different. He sat at his desk leaning on an elbow, reading over his notes from class.

"Armin!" He looked up at the sound of his name. His best friend, a moppy haired brunet, bouncing his way, shutting his book despite his protests.

"Come out with us tonight, we're going to Sasha's."

"Ah," he began, searching his arsenal for a fresh excuse. "Eren-"

"Come on man you never go out with us! It's just Sasha! Aren't you guys friends?" Eren pleaded, staring intensely into his blue eyes.

"Yeah, but only in class. Eren, you know that's not my scene. Go have fun without me." Armin nudged him towards the door of his room, flashing a smile.

"You're really okay just staying home?" Eren asked, concern lacing his voice as he brought a hand up to pat his head of blonde hair that was pulled back into a bun. "You work way too hard; let loose sometimes! The best stress relievers come from the ladies, after all, Armin."

"Gross, man," Armin rolled his eyes, "this is why you're single."

"But Armin-"

"I'm okay, really. You know me. Anyway, go have fun. Be careful, though." Armin reassured, bumping fists with Eren on his way out. He watched in amusement as the green-eyed boy waved him off, walking out of the room and shutting the door behind him.

An hour later Armin found himself yawning over his book. He rubbed his eyes and reached for his phone to check the time. "12:34AM" stared back at him, and still nothing from Eren. The blonde sighed, wondering often how his friend managed to live until today based on how reckless he is. Armin swiped over to his messages.

12:35 am

"Hey Mika, do you know where Eren is?"

He set his phone down, and it buzzed a couple minutes later.

12:37 am

"I heard he was at Sasha's, probably doing something stupid again. I'm tempted to go check on him but I don't want him to get all mad."

Armin chuckled.

12:37 am

"I know, sometimes I can't help but worry about him, you know?"

12:38 am

"Don't even get me started. You've been there for all the fights we've had regarding his idiotic life choices."

Armin's fingers hovered over the keyboard hesitantly. Would it be too risky…?

12:40 am

"Do you wanna come over?"

Three gray dots, and he held his breath.

12:40 am

"Yeah sure. Be there in 5."

And she was. Mikasa stood in front of his door in a gray hoodie and Nike shorts, lazily leaning on one hip.

"I like your hoodie." He complimented plainly.

"Thanks," she stepped through, inviting herself in, and made her way up the stairs to his apartment, "it's my brother's."

"That's a small hoodie for a guy." He commented.

"Have you seen Levi? He's four inches shorter than me." Mikasa shook her head jokingly, flopping onto his bed as she's done millions of times before. "Why'd you call me over? How can I be of service?"

"I got tired of studying. It's Friday after all." Armin joined her on the bed, both of them looking up at the ceiling.

"Tch, you're always studying. You even study more than me, and I'm Asian." She laughed, throwing a stray crumb on the bed at his face.

"Yeah. I think I stress myself out too much. Maybe Eren's right." He sighed, turning to face her, "Maybe I need to destress once in awhile. He does say that the best stress reliever-"

"-comes from the ladies, I know," she finished for him, rolling her eyes so far back, she swore she saw the brain damage she was getting just from thinking about it. "Disgusting. I tried it with a girl once, I wasn't into it." Mikasa cut him off scowling. The blond reeled back.

"No way, really?" he gazed over her, analyzing her nonchalant expression.

"Yeah, man. Sasha, when we bunked together on campus."

"What the hell, Mikasa, I had no idea." Armin trailed off before offering her a sad smile, "Can I ask you a question?"

"Shoot."

"Why do you like him so much if all he does is hurt you?" He inquired, watching her carefully.

"I don't know. I'm an idiot." She fiddled with the string of her hoodie, "it's like he can lead me on and break my heart, apologize, then I'd be ready to be hurt all over again right after." Her demeanor became somber, throwing an arm over her eyes.

Armin laughed at the accuracy of her statement, "Oh, Mikasa. You deserve to be happy."

"You're absolutely right. I should just jump on you instead." Mikasa threw out there, half jokingly, pushing herself up to lean on her palms. Armin sat up.

"I mean," he began, ignoring how red and warm his face was getting by the second. "Would you...be willing to try it?"

"Armin! Armin Armin Arminnnn," Eren called out from the foot of the stairs, climbing slowly as his world spun around him. "Bro!" He yelled again.

Up in his room, Armin sighed in annoyance, detaching himself from Mikasa's exposed neck and removing his hand from her ass. The fabric of her bra brushed against his bare chest as she sat back up. "Sorry. My idiot best friend is home."

Mikasa rolled her eyes, "yeah, at two in the morning." she kissed him again, grinding against his thigh. Armin groaned at the contact, using all of his willpower to push her away before Eren came busting in, but her grip on him was relentless.

"Mikasa-" She cut him off with another kiss, seemingly uncaring of what consequences it was bound to bring.

"Armin-!" and the door flew open. "Holy shit." The brunet froze.

The person in question, pulled away from her sheepishly and turned around, passing Mikasa the covers to shield herself from the drunken boy in the doorway. He scratched his neck tiredly.

"Hi, Eren." He said pathetically.

"What the fuck, Armin?" he slurred, crossing the threshold to approach the duo in the bed.

"Is there a problem, Eren?" Mikasa asked, looking at him with the slightest trace of anger that he would have noticed if he wasn't so shit-faced. Their current lack of clothing was not assisting the situation in the slightest.

"Armin, you- and Mikasa- but I thought you were-"

"Breathe, buddy." Armin watched him trip over himself.

"You and Mikasa have been banging behind my back?" Eren nearly shouted, "I thought you never did this kind of shit before? I was under the impression you were a nerd!" He probably knew he was being rude and crossing so many boundaries at once, but the alcohol in his system was greatly hindering his ability to think and form words properly. Not that it was much better when he was sober.

"Thanks. Eren, I'm not a virgin. And I'm not innocent, either. I don't know why people always think that of me." Armin trailed off in thought.

"Wait, okay, okay, wait" Eren paused, "Okay. How long has this been going on?"

Mikasa rolled her eyes. "It just now happened. We didn't even get that far until your drunk ass came barging in."

Eren's attention shifted to her. "You," he began, pointing a drunk finger towards her, "I thought you liked me!"

"Yeah, I fucking do," Mikasa huffed, throwing the covers off her body to retrieve her hoodie and ignoring the way his green eyes raked over her body, "but that wasn't going anywhere, and Armin happened to be here, unlike you."

"Honestly, Eren," Armin interrupted, "we're both always so worried about you since you're always going out and getting into trouble. We figured we'd see each other out instead of worrying about you. You were the one who said that the best stress relief comes from sex."

"Oh," Eren wanted to punch himself in the face, "so...so I'm responsible for this?" Armin nodded. Eren felt his stomach drop, unjustified jealousy bubbling in him.

"Huh," he muttered, fighting the sudden urge to tackle his best friend, "Excellent."

Silence followed, and he staggered backwards, "Excellent," he repeated, his eye twitching from being overloaded with a hundred different emotions. When they still didn't say anything, he nodded his head drunkenly, "Excellent."

The blond examined him with caution, having a feeling he knew what he started. Across the room, Mikasa reached for her stuff.

"I'm heading out. Make sure he doesn't throw up on the floor." She pushed past him, but he caught the door before she could slam it. Eren didn't forget to give his best friend a nasty glare before following her out gracelessly.

"We need to talk," he slurred behind her.

"No we don't, Eren."

"Yes, we do."

"What's your problem!?" She turned around and he almost ran into her. "Why do you even care about what I do?"

"I don't know, okay?" he gave up before he even began to fight. His current inebriated state made it harder to filter whatever came out of his mouth, so the honesty was spilling out rather easily.

She looked at him, anger growing by the second, "What do you want?"

"I…" he trailed off hesitantly, but when he saw the pained look on her expression as she tried to suppress her hurt with anger, he decided to give in to the honesty that the alcohol was advocating so strongly. "I want...to be in a real relationship, to have someone to be there for me that I can count on all the time, and make me feel like this world isn't just out to get me."

Mikasa nodded her head, her nostrils still flaring from pure anger, "Why don't you get one of your hoes to do that then?"

She tried to push past him again, clearly finished with this conversation, but he stepped in front of her. "I don't want that!" he exclaimed, startling her slightly. "Do you ever think maybe I just do stupid shit like that because I'm scared? Because I know, and I've known all along that I want to be with you, but you've always just been out of my league?"

"W-what?"

"I love you, dumbass," he told her gently, affectionately, watching as her tough facade began to fade. It didn't last very long though. She then held her chin high again and poked him in the chest, sending him a few steps back.

"You're the dumbass," she fought the smile tugging at her cheeks, but he did, and he tried to close the distance between them clumsily. She put out a hand to stop him when he was merely three inches away, "no, you're drunk." she could smell the alcohol in his breath.

"But...Mikasa-"

"We'll talk about this tomorrow," she stood him upright and watched as his expression spoke for him. "For now, you need to go apologize to Armin." her eyes now missing the angry glint in them.

Eren knew she was right.

So he found himself stumbling back into Armin's and running a hand through his hair tiredly. He spotted his best friend in the process of putting a shirt back on; his toned back facing the brunet. Eren stepped forward, almost barreling into Armin and wrapping his arms around his waist. The blond found himself repressing his laughter at the position he was being held in.

"I'm sorry, bro." he mumbled pathetically into his hair, now down to his shoulders.

"I know." Armin chuckled, patting his forearms gently. "I'm sorry, too. It wasn't right for me to do that, either."

"I love you, man." he continued and Armin had to pry his arms off of his waist before turning around and nudging him towards his own room.

"Okay," Armin smiled, "you've had too much to drink. Let's get you to bed."