A/N: To answer the question, did Mikasa ever find out about them? Well now we know... She's known the whole time. XD (A moment at the end of chapter one, a fanfiction dedicated to Eremin week)

It's honestly realy sweet to see people not wanting this to end. You guys are so kind. ^^ Please enjoy this extra!

It's A One Time Thing (Modern AU) They're are the only ones who trust each other enough to go this far. They keep sayings it's a simple thing, which it means absolutely nothing, but, to be honest, that couldn't be any farther from the truth.

The first to wake was Eren. His groggy, green eyes opened to see the ceiling of his living room and the tiny speckled patter the paint held. The light shining into the room from the open windows and thin, blue curtains made his eyes strain against it, wincing to keep them open yet keep the light out. He groaned quietly, but it was loud enough to stir the smaller male sleeping on him.

He looked down at his naked friend, watching as Armin's blue eyes slowly opened and focused on nothing in particular. The blond shifted on top of him, but only for a few moments before a hand reached up to rub his heavy and half-lidded eyes.

"Good morning, bed head." Eren said, making a snooty comment on how Armin's hair was tousled and was flowing in many different directions. Armin didn't respond at first; he simply took in a deep breath and let it out in a heavy sigh. He dropped his head back down on Eren's shoulder, taking in his natural scent mixed with the sweet and familiar smell of sex Armin had come to know so well.

"Morning..." Armin mumbled, not bothering to come up with any good comebacks to insult Eren with. He was too tired and too sore to do that so early in the morning. He shifted once more, rolling off of Eren's body only to lay by him on the couch. The blanket on them shifted and he distantly wondered who it was that put the blanket on them. It wasn't the first or most important thing on his mind, of course. Either of them could have done it while sleeping.

"Sleep well?" Eren asked while moving to lie on his side, cradling Armin against his chest.

"Mhm..." Armin responded while sighing. "What about you?" He asked.

"Like a rock." Eren rubbed his shoulders as he spoke. Armin smiled at him, his tired eyes gazing up at his friend with a comfortable trust.

"That's good to hear." He said. He dropped his head back down on Eren's shoulder, closing his eyes and blocking out the painful sun that shouldn't have even been up. "Eren, what time is it?" Armin asked.

"What time...?" Eren asked and rolled back to grab his phone sitting on the coffee table. He noticed the mess they had made the night before, consisting of three bowls of uneaten chips (one being on the floor), two bottles of soda and a half eaten bag of popcorn. He groaned as he grabbed his phone, knowing he would have to clean that up before Mikasa got home. He sat back against the couch while turning on his phone.

"It's too bright. Why can't you get better curtains?" Armin asked as he hid his head away to block out the sunlight blinding him.

"Those were Mikasa's choice, not mine." Eren explained as his phone turned on with a moment of happy music playing from the speakers. Eren waited for the screen to turn on, and once it was, he noticed two this: The time and a text message from Mikasa. He opened the text message first, wanting to see what it was his sister had said. The message read:

Mikasa:

"Eren, I'll be home in about an hour. Want me to grab any breakfast on the way home?"

Eren sighed as he ignored the message. Instead, he scrolled through the messages while checking the time.

"Uh oh..." He muttered.

"What...?" Armin lifted his head slightly and asked.

"It's past eight." Eren stated.

"It's what?" Armin shot up from his spot on the couch an exclaimed.

"Yeah, it's eight thirty-eight." Eren held up his phone for Armin to see the time.

"Oh no, I'm going to be late for work!" Armin sat up more to start the frantic search for his clothes. Eren sat up from under him, but he wasn't in such a rush to get to the reality that was life as Armin was. "Underwear? Where is my underwear?" Armin frantically asked, his pants and shirt already in hand.

Eren laughed at the sight of his flustered friend and bent over the side of the couch. He vaguely remembered what he did with his friend's underwear last night, dropping then somewhere on the floor only minutes before taking him, so it wasn't hard to find them. He reached under the coffee table and pulled them out, holding them up for his friend to see.

"Is this what you're looking for?" Eren asked teasingly. Armin spotted his underwear in Eren's hand and reached out for them, but Eren pulled them back and out of his reach.

"Come on, Eren! I don't want to be late! My boss will fire me!" Armin whined as he leaned forward for another try at grabbing them. An utter fail, for Eren pulled them out if his reach again and yanked Armin down onto his body.

"You know, you keep saying that, but you haven't lost your job yet." Eren stated with a smirk on his lips. Armin groaned as he continued to reach for them, leaving himself exposed for Eren's lips to fall on his neck. Armin gasped in surprise, and then bit back a small moan. Eren had made his way to that sweet spot just below Armin's ear, causing a shudder to dance through him.

"N-No, Eren don't. Don't get me worked up n-now." Armin pleaded. Eren didn't listen, his free hand finding the soft skin of Armin's butt and kneading it between his fingers. Armin unintentionally sighed, rolling his hips forward to seek unwarranted pleasure.

"You're practically begging for it." Eren whispered against his ear. His hot breath fanned against his skin, causing goose bumps to rise on his warm flesh. Armin nearly lost it there, ready to beg Eren for more, but he had to keep in mind that he had to go to work, and so did Eren. They both needed to get ready, lest they get into any more trouble than they already were.

"Eren... I-I can't... We- Hng..." Eren sealed his lips over Armin's to shut him up while rolling the two over so Armin was on his back. Armin closed his eyes and whined as he turned his head to the side, trying to resist Eren and his advances, but he was losing the silent war. "W-We'll be late…"

"Is that what you're worried about, honestly?" Eren asked in a whisper against his ear. Armin rolled his head back, his lips unintentionally brushing against Eren's. He couldn't handle any more waiting. He couldn't deny any more that he wanted Eren, even though they had just had sex hours before.

"Damn it, Eren…" Armin mumbled against his lips before pulling him down for a kiss. Eren returned it gratefully, his hands cupping Armin's cheeks while slipping his tongue into his mouth. Armin let out a small, regretful and pleasurable moan into Eren's mouth. When pulling away to breathe, Eren attacked his neck with open-mouthed and wet kisses, sucking on the skin hard, but not hard enough to leave a mark. He knew better than that.

Eren smirked against his skin, wrapping his arms around him in an embrace that made Armin feel the hardened flesh between Eren's legs. He shivered with the small amount of pleasure that surged through his body, his own erection giving an involuntary twitch. To tease him, Eren pulled his hair back, exposing his neck more for his kisses.

"You gave in so easily, Armin." Eren mumbled against his skin. Armin groaned in agitation and yanked Eren by the hair to kiss him, effectively shutting him up. It was a good thing too. Just as Eren's hand slipped from Armin's hair to grab at his member and stroke it, both heard the distinct sounds of keys in a lock. Eren and Armin lifted their heads, listening as the front door opened and footsteps sounded mere feet from them.

"Eren, I'm home!" It was Mikasa. Both Armin and Eren froze, bodies still together and obviously aroused on the couch. They listened to the sounds of her footsteps, of her humming contently as she sorted through the morning mail. With only the blanket to cover them (and barely at that), they didn't have anything or any way to explain to Mikasa why they were naked, on top of each other, and red in the face.

'We're screwed!' Was a thought they both shared. They heard Mikasa sigh, grumbling to herself about the mess they had left in the kitchen, but it seemed like she hadn't noticed the two yet.

"Eren…?" She called out. They heard her rushed footsteps leave the living room, and the two breathed out sighs of relief as they sat up.

"Get dressed, hurry!" Eren whispered in a panic, handing Armin the underwear he previously denied him. Armin did as told, throwing on his clothes in record time and running his fingers through his blond hair to fix the tangles Eren had created. Eren did the same, and added rubbing his face in hopes that it'd get rid of the obvious arousal.

"Oh, there you are." Mikasa walked right back into the room, mail still in hand with her backpack hanging off of her right shoulder and arm.

"Y-Yeah, here we are." Eren said, his voice cracking in pressure at trying to hide his breathless state.

"Armin, you're here too," Mikasa said. It wasn't much of a question; it was more of an observation.

"Yeah, I spent the night." Armin flushed, his eyes diverting to the messy floor so he didn't need to look at her. He didn't want her reading the truth in his eyes.

"Oh god, Eren." Mikasa whined and waved a hand in the direction of the coffee table. "Look at this mess. I'm not cleaning this up." She groaned in agitation.

"S-Sorry, I'll clean it up." Eren apologized.

"Don't you have to go to work?" Mikasa asked while pushing her black hair out of her face.

"Yeah, yeah I do. Not for another half an hour though." Eren said. Mikasa looked to Armin, beckoning for an answer from him with her eyes.

"Yeah, I was just leaving too." Armin stood up from the couch, making sure his shirt was low enough to cover his aching erection straining against his pants. "Thank you for inviting me, Eren." He said as he paced himself over to the door.

"Yeah, no problem." Eren waved to him and ran his fingers through his hair. "I'll see you later?"

"Of course." Armin slipped his shoes on and waved to Mikasa. "See you later," He said and dashed out of the door, leaving the two siblings to themselves. Mikasa sighed as she rolled her neck around, leaving Eren to the couch and mess the two had created.

"Well, I'm going to go sleep. Christa kept me up all night with her talking." Mikasa mumbled and sighed when a kink in her neck was worked out. "You can clean up in here when you get back from work."

"That sounds good," Eren said. "I-I'm going to go take a shower before work. I'm uh… Covered in sugar." Eren looked down at himself, looking at his disheveled form and winkled clothes.

"That would be a good idea." Mikasa stated. Eren left the couch in favor of leaving the room and taking a shower. Mikasa watched her brother disappear behind the door, and once she was left alone in the messy living room, she let out an audible sigh. "Good lord…" She mumbled.

Reaching into her pocket, Mikasa pulled her cellphone out and searched through her messages. She saw the most recent one, the one she sent to Eren. Double checking it, she noticed that it had been sent out and had been seen by someone.

"Didn't Eren bother to check the time when the message was sent? I sent it at six in the morning. I thought that'd be enough time for those two to finish up whatever they normally do and hide." She muttered. She honestly didn't expect that when she came home at seven in the morning, she'd see the two butt naked and sleeping together on the couch. The mess they had made was the least of her worries; she was more concerned with stopping the bloody nose the sight had given her.

"It's like they're flaunting their relationship…" Mikasa mumbled as she set her backpack on the counter. "They could at least do better at hiding it. How many times am I going to walk in on them and then leave to do something else?" Mikasa rolled her eyes and looked at the couch. Eren's cellphone set aside on the floor, Mikasa picked up the discarded blanket and folded it.

"Did they even bother to wonder who put the blanket on them?" She questioned herself.