This was on my lemons book, but I finally decided to give this it's own book, enjoy!!

Alright, enough fun,” Levi called toward the ocean. Eren turned around where he stood in the waves and saw that everyone was obeying immediately. Mikasa waited for Eren to wade through the waves to the shore. Then, the two burnt their feet as they walked through the sand to where everyone else was gathering.

“Yes, if we’re going to make camp here for the night, I suppose work must start already,” Hange said. She was clearly disappointed as she gazed down at the large conch shells she held in both her hands. “Well, Levi, start setting up our tent.” He turned and walked a few paces off further from the water and did as she asked. “Hm. Sasha, Jean, Connie. You will prepare dinner. Armin, you watch Sasha and make sure she doesn’t eat everything. Also, be prepared to transform if necessary. Eren and Mikasa, go look for firewood. Jean, make sure the horses are fed too. Levi and I are going to take a nap and we’ll take first watch tonight.”

There was a general outcry of “Yes ma’am,” and then everyone turned in different directions.

“There were some trees west of here a bit. Let’s go that way,” said Mikasa as she pulled her boots back on.

“Fine,” Eren answered as he glanced around. Armin stood small, with his arms crossed over his chest in the middle of everyone else. Jean was striding off to where the horses were tied. Connie was ruffling Sasha’s hair as she opened a satchel of food. Hange slid down on the sand next to Levi, who had made quick work of their simple tent. He was lying with his arm over his eyes despite the shade.

Eren left his boots were they lay on the sand and hurried to catch up to Mikasa, who carried a small machete in one hand.  She shoved a burlap backpack at Eren once he caught up.

They were quiet while they walked over the wet sand along the shore until they were well outside of earshot of their comrades.

“I would run on this sand every day if I could. I think it would help,” Mikasa said quietly.

Eren had to strain to hear her over the waves but he thought he understood her right. “Help what?”

“To keep me fit.”

“You’re fit enough without it.”

She glanced sideways out of the corner of her eye at him. Bowing her chin slightly, she said, “Thank you.”

They were quiet again except for the crashing of the waves. Soon, they’d rounded a bend in the beach. To their right, a steep cliff of about thirty feet or so hid them from the far-off campsite.

Eren wondered aloud, “Should we try to find a way up? Or do trees grow in sand?”

“I don’t know. I think we should probably climb, but I can’t see a good way up without gear—”

“Wait, I see something up ahead. What is that?” Eren pointed. Off in the distance, there was something which looked like a fallen tree on the sand near the cliff side. He ran ahead and Mikasa ran after him. Surely enough, it was a log that had been washed up on shore and had dried out.

“Will this work?” Eren asked but Mikasa was already hacking the log apart.

Mikasa answered between hacks, “Yes, it will work quite well. It is dry and there is enough wood for hours if the fire is kept small.” Eren wanted to help her but he knew enough not to suggest that she couldn’t do it on her own. So instead, he stood and watched her hack the log apart until he could settle the pieces of wood into the bag she’d given him.

Once she was finished, Mikasa laid the machete down in the sand and sat down next to Eren, who was still stacking the wood in the burlap sack. Sweat was dripping down her temples and down the sides of her neck.

“It’s really hot,” Eren said, because he knew Mikasa wouldn’t complain.

“Mm, yes it is.”

“It’d be nice to go back in the ocean.”

Mikasa glanced at him and then looked out at the ocean as Eren stood up. Mikasa stood too and quickly wiped her forehead. “We should get back. They will need the firewood to cook the meat that Sasha hunted.”

“Yes, but we have plenty of time. Everyone’s already had a ration and it is only midday. The meat is for later.”

“Eren.” She shook her head. But Eren was already unbuttoning his shirt.

“Mikasa,” he mimicked, and turned his back to the waves as he faced her. “Are you afraid of it?”

“Afraid of what? The ocean? No.”

“Then come on. Levi is sleeping. No one else will care.” Eren unfastened his trousers and pulled them off so he was left in his underwear. He saw Mikasa’s cheeks color and wondered if it was because of the heat. “I bet they’ll all be swimming when we get back anyway.” He took her wrist and led her to where the waves reached up to their highest point on the sand before they fell back again.

“Eren…” she said again.

He loved it when she said his name like that. He always had. He could never understand why though and so he tried not to think about it.

Turning away and dropping her wrist, he pulled his underwear off and waded into the water.

“Ah, it’s so cold!” he yelled in the same voice he’d use if yelling at an enemy. Once he was waist-deep, he turned and moved his arms so that he could stay in place despite the waves. “Come on!”

“Eren, what if there is some creature in the water! Come back! You’re too far!”

“Too far? I can still stand up here!” He was disappointed that she wasn’t getting into the water yet. She really needed to cool off before she got heat stroke.

“Eren, come on.”

“No.”

“Fine. I will come and get you out then.” She pulled her boots off.

He swished his way around so he was facing out toward the rest of the ocean again. He felt his throat tighten once more at the sight. The thought again drifted through his mind: how many were on the other side…?

He heard a splashing sound over the waves. He knew without turning that Mikasa had followed him into the water. He couldn’t help but smile as he turned to face her again.

“Ha! I won—” But then he nearly swallowed his tongue. Mikasa was wading into the water but she was only waist deep when he’d turned. He caught a glimpse of her breasts before they were submerged in the water.

“I don’t know how to swim,” she called to him, though he barely registered what she was saying. The sight of her bare chest had burned in his eyes as though he’d looked directly into two bright suns. “Eren! Are you alright?!” She was struggling to push through the water toward him.

“I—uh…”

“Did something bite you? What’s wrong?!” She had nearly reached him now but as she was now slightly shorter than him, she couldn’t quite reach the bottom and still keep her chin out of the water. “Eren—” But she got a mouthful of saltwater.

“Why did you swim out this far?!” he snapped. “You’ll drown!” Under the water, he grabbed her arm and pulled her roughly a few feet closer to the shore without looking at her. His roughness was slowed by the water, but even so, they made an enormous splash as they both slipped on the sandy ocean floor. They were pulled under the waves.

Eren had learned to swim in streams as a child on outings with his father. But that had been before Mikasa had come to stay with them and he knew she couldn’t possibly know how to swim. He didn’t have to think about it: he automatically pulled Mikasa up again.

“I’m sorry—I’m sorry—I’m such an idiot—” he said once they both broke through the waves and breathed air again. Mikasa was spluttering a little but she seemed alright.

“It’s okay. I just slipped,” she said to the waves and coughed a few more times.

“Are you okay?” he asked.

She looked over at him and instead she seemed to be assessing his face for injury. For the first time, somehow, Eren didn’t get annoyed at this. Instead, he found it endearing. He wanted to hug her and almost did, but then he remembered that he was naked and she was at least partially so.

“Um… yes, thank you.” She kept gazing at him. Eren couldn’t look away either. He didn’t want to look away. Her gray eyes looked silver-blue in the sun. Her black hair was shining as though it was slightly blue too.

He was overcome with the urge to kiss her then.

What had gotten into him? He was sure Mikasa would smack him (at least) if he did this. Was it the sight of her chest that had done this to him?

He watched as Mikasa waded closer to him. Slowly, she found his hands under the surface as she inched her way through the water… and then she grazed her fingers up each of his wrists... then his elbows… his biceps…

“Are you sure you are alright? I thought I felt something change in you… in my heart…” She moved one hand up his shoulder and wove her fingers into his now overlong hair.

“Y-yes.” He let his hands be buffeted in the waves and his fingertips grazed Mikasa’s side. He saw the color rise in her cheeks when he did this and for once, he saw this color in her cheeks differently. How many times had he seen her blush? But when had she? His mind was a blank buzz of hopeful confused fear. His heart pounded as he dared to touch her again, and this time, he let his hands rest firmly on her hips.

Meanwhile, her hand grazed its way down his jaw and came to rest on his cheek. “Oh Eren…” and she closed the gap between them. And suddenly she was kissing him.

He didn’t think. He couldn’t think. There was too much. Could this be real? Was he actually in the ocean right now? Was he kissing Mikasa?!

He’d never kissed anyone before. He briefly wondered if he was doing it right but then Mikasa’s breasts were pressed against his chest and she was pressed against the rest of him. It felt too good. He never imagined he’d be naked the first time he kissed a girl…

He forced himself to push her away. “Mikasa…” He shook his head. And to his dismay he watched as her face clouded with tears. “No, uh, Mikasa—I, please don’t—”

“I’m sorry. I know you don’t—oh…” she covered her mouth with one hand and turned away. “Please go back without me. I’ll follow you later.”

“I didn’t mean to hurt you Mikasa, it’s just that—”

“Please don’t, Eren!” she yelled with her back turned.

“Damn it,” he whispered. He stared at the back of her head for a moment and could think of nothing to say. Defeated, he waded back out of the water.

But what if she slipped again and couldn’t get out of the water? He couldn’t leave her there on her own. He pulled his underwear and trousers back on, soaking them with the droplets still clinging to his legs. “Mikasa! I won’t leave you there! What if you slip again?!”

She only half-heartedly waved him off.

Gritting his teeth, he pulled his shirt back on and buttoned it. “I’ll turn my back until you tell me otherwise, alright?! I’m not leaving you here!” He saw her contemplate this and then after moment, she started wading back toward the shore. He turned away as he said he would and then strode up to get the bag of wood and the machete.

A short while later, Mikasa was dressed and stood just behind him, so he turned back to face her. She pulled the machete from his hand and carried her boots along with it as she strode away. He watched her walk away as he hoisted the bag of wood to his back and tightened the shoulder straps slightly. And suddenly, he realized he was staring at her bottom. Since when was Mikasa’s bottom something he stared at? Had he always stared at her and was only just now realizing he did?

Unbidden, the fresh memory of the feel of her naked hips under his hands came to his mind. He felt as though his heart had too much blood for a moment from all the unfamiliar emotions he was feeling. He wanted to touch her again. Why had he stopped her?

And anyway, what had just happened? Had he really just kissed Mikasa?!

“Wait!” Eren said once they’d nearly rounded the curve in the beach. “I want to talk to you for a minute.”

Mikasa stopped and turned to face him. “What?”

“Do you… do you really feel like that toward me?”

“But you don’t feel like that toward me. I know. I’ve always known. It’s okay. Please forget what happened. I misread you.”

“But I—have you always… did you… I mean, I know you care for me. I care for you, too. I will always take care of you any way I can. You know that, right?”

“Yes,” she whispered and turned to continue walking but he stopped her with a hand on her forearm.  The machete hung between them.

“I had no idea that you... I mean, I know you don’t see yourself as my sister… I guess I didn’t know what I thought.”

Mikasa bowed her head. “But you know now.”

Did he know now?

“Yes.” He swallowed and said, “Mikasa, I’m sorry I stopped you. I… I want to feel your hips again! I want to kiss you again!”

Mikasa looked up sharply but said nothing.

He dropped his bag of firewood to the sand and lunged at her. She tossed the machete a few feet to the side just as Eren kissed her, hard.

“Mm!” Mikasa said against his lips in surprise. And then she was laughing into his kisses and he was laughing too.

She unbuttoned his shirt and pushed his sleeves down his arms. As he gently broke their kiss, he let his shirt fall to the sand.

“Don’t do anything you wouldn’t… want… That’s why I stopped you before.”

She glanced up into his eyes and nodded meekly. Then, she led his hands down her sides and pressed his hands to her hips. In a sort of question, she looked into his eyes again.

“Mm.” Eren nodded. Then he watched as Mikasa slowly unbuttoned her shirt and dropped it to the sand behind her. She did the same with her bra.

“You don’t have to leave your hands there.” She glanced up once more before they both looked down at his hands on her hips. Softly, she slowly led his palms over her abs and to her breasts.

Eren whispered, “O-okay.” Gently, he ran his fingers over her nipples until they were hard peaks. Seeing her body change like this, he checked her face for her reaction. He was surprised. Her eyes were closed and her head was tilted to the side a little. “Does that feel good?”

“Yes,” she whispered back as softly as she could. He couldn’t hear her over the waves but he knew what she’d said. He wanted to kiss her again because she was beautiful. So he did.

She responded immediately and soon, he felt her hands on the top of his trousers. She was undoing them.

“But what if—” he started.

“It’s okay…”

“Are you sure?”

“Hange insisted on giving me the shot.”

Eren knew what that meant. ‘The shot’ kept girls from getting pregnant for months at a time. It was usually only issued for married women in service… He nodded.

Mikasa watched her hands as she pulled Eren’s trousers down and he kicked them behind himself onto his shirt.

Though he was nervous, Eren managed to keep his hands steady as he unbuttoned Mikasa’s trousers in turn. He knelt and pulled them gently down her legs and off her feet. Glancing up at her face for reassurance, he kissed her kneecap. He didn’t know why he did it, other than for the simple reason that he wanted to. The feel of her skin under his lips made him purely happy.

She half-smiled at him and laughed a little.

He was struck with the desire to kiss her everywhere. He kissed the inside part of her lower thigh, then higher and higher up again. He trailed kisses along her panty line up her hip and along the crest where there was a shallow crevice under the muscle there. When he trailed his lips across here, he reveled in the taste of her salty skin and the feel of her hands threaded into his hair.

“Eren…” Gingerly, she held him against herself so his face lay against her panties. They were white and damp and dusted with sand.

“Mikasa.” He hugged her around her thighs and breathed in her scent. He was the opposite of mocking when he said her name now, and he was almost desperate with his need for her. Hooking his thumbs into her panties, he pulled them down while his cheek still rested against her.

His heart felt like this couldn’t possibly be the first time they would make love. Rather, he felt as though he’d done this every day in some way with her… and yet, the rest of his body was silently screaming in the newness of the feel of her skin under his lips… her thighs… her hands in his hair… the taste of her down there in his mouth…

She knelt shakily before him. As he kissed her neck, he lay her down on the sand. With half lidded eyes, she pulled him so he was on top of her. Holding himself up with one of his forearms on the sand, he gazed down and tried to smile at her.

“Oh, Eren.” Tears sprang to her eyes. Where the tears fell, he kissed the corners of her eyes. He knew she was alright, really.

These were the same sort tears she’d shed that day. It had been the day which seemed like they would surely, finally die. But somehow, her love for him had triggered the coordinate power inside him. As he kissed Mikasa now, he finally understood. It was Mikasa who had awakened the power and gave him strength. No one else. Because of her, he saved her life. And he had finally defeated the titan—a royal titan at that—who had killed his mother…

 Mikasa ran her fingers through his hair and then down his back.

“It’s okay,” he said into her ear, “we don’t have to. I know now… I know…”

“Don’t pull away from me again,” she demanded and grazed his nose with hers before kissing him again. “Please.”

Slowly she ran her hand to Eren’s front, lower and lower, until she found him. Slowly, she ran her hand down his length and up again. In response, Eren lay his forehead against hers and let the air rush from his lungs. Then, she guided him into herself.

“Mikasa…” he whispered against her lips.

“Oh…”

“Am I hurting you?”

“No, not really…”

“Yes I am—”

She grabbed his shoulders and held him still. “Don’t pull away.”

Eren pushed the hair away which always lay across her face and kissed her cheek. Then, she pushed his hip away with her hand and he slowly pulled out.

She guided him back into her again… and a little quicker the next time…

Eren pushed his hand through the sand under her neck. Cradling her head, he kissed her as he pushed into her again. He hardly realized the fact that tears now fell from his eyes too.

How he could love someone this much and have only just now figured this out…?

But he knew: the ocean had changed everything. He’d needed to see the ocean before he could see anything else.

Mikasa’s hips urged him faster and faster.

“Mikasa!” he grunted loudly with his forehead against hers. But she wouldn’t let him slow down and soon, she pushed him over the edge.

Eren lay his head between Mikasa’s breasts as she cradled him against herself. He listened to her heart slow to normal while the waves crashing at their feet seemed to quiet themselves for a while.

Later, they dusted as much sand as possible from themselves and dressed each other. Once Eren hoisted the wood to his back again, Mikasa took Eren’s hand in one of hers and carried her boots in the other. Eren found the machete where it had landed a few feet away and slowly, they made their way back to camp.

Sasha was clearly angry that they’d taken as long as they had. “We could have been roasting the meat for an extra hour! It is better if it is on a low heat for a longer time! It makes the fat melt! Where did you go for the firewood?! All the way back to Trost?!”

“Shh, you’ll wake Hange and Levi,” Connie said.

Jean’s face fell when he saw that Eren was holding Mikasa’s hand. Eren wondered if it was because he felt like Sasha did about taking too long or if he was simply jealous...

“Hurry up and build the fire!” Sasha wiped drool from her chin. “I want to roast the meat!”

As he grinned at Eren and Mikasa’s entwined hands and sand-covered clothes, Armin looked like he was a cross between an angel and a demon. Pacing toward his two best friends, he helped Eren with the firewood. And as they three built the fire, every once in a while, especially when Eren and Mikasa would smile at each other, Armin laughed softly to himself.

Later mates...