Eren was sitting in what had turned into his spot in the mermaid tank, at the edge of the sunning rocks, legs crossed with his notebook in his lap, scribbling away. Levi meanwhile was treading water in front of him, quickly getting irritated because he couldn't get into his spot in the tank, Eren's lap, while that notebook was in his way. He glared at it, hating this new intruder, even if it was just an inanimate object and he knew it, before barking softly.

"Yes?" Eren replied, not looking up from his work. He was beginning to learn each of Levi's specific barks. Some were loud and deep, those were warning barks for others to stay away. Some were sharp and clear, meaning he had heard something. He also had a much softer, almost dreamy "boof" kind of bark that he made when he was half awake and thought he had heard something, but was most likely just imagining it. This was one was clearly just meant to get Eren's attention.

Levi barked again, more insistently, causing Eren to look up. Once he did that, the mermaid moved closer, reaching up and curling his fingers around the edge of the notebook, beginning to pull it aside. Eren hastily held it in place.

"No, you can't have that," Eren chided, "I need it still."

However, it was going to take much more than that to put Levi off. He pulled himself up onto the rocks beside the boy, pawing at the notebook again. He hooked his fingers through the rings, trying once again to pull it aside. Eren once more pulled it out of his reach, glaring at him.

"Levi, cut it out," he huffed, and then placed it back in his lap, turning his face away from him.

The mermaid backed off for a moment, sighing in frustration as Eren bent over his work again and returned to writing. But then he decided to change tactics. Force wasn't working, and besides, he didn't really want to make Eren mad. Instead, he lowered himself to the rocks, trying to look as submissive and small as he possible could. He placed his chin on Eren's thigh, whining subtly until the boy finally looked over in his direction, his expression amused this time.

"Really?" Eren deadpanned. Levi amped up the pitiful whining, and the boy rolled his eyes, finally relenting. "Oh my God, alright. Come here."

He lifted his notebook up, and with a delighted chirp, Levi dove into his lap, hugging Eren's knee and curling his tail around him. When he didn't feel Eren's hand immediately settle into his hair, he reached up, groping for one of his hands and trying to place it on his head. Seeing what he was doing, the boy moved both his hands and his notebook further out of reach. "No, Levi. I really do have to finish this before lunch."

The mermaid fixed him with an irritated glare, and tried to reach for his hand one more time. But when Eren gave him a warning look, he stopped, instead settling himself down into Eren's lap, grumbling. The boy rolled his eyes again, though he was smiling.

"You are so spoiled," he pointed out, "Though that's mostly my fault. Actually it's entirely my fault."

As if to add to punctuate his statement, Levi let out a loud purr, nuzzling his thigh and hugging his knee tighter. Eren shook his head fondly, and lowered his notebook until it was leaning against Levi's side, using him as a makeshift desk. The mermaid "mrrr"ed in surprise, raising his head to see what he was doing, before he calmed again. However, he didn't lay his head back down. Instead, he stared over his shoulder at Eren's pencil scratching across the page curiously.

Levi chirped sharply to attract Eren's attention again, and when the boy looked up, he signed, "What you write?"

Eren would have signed back, to keep Levi's practice going, as he was still learning, but at the moment his hands were full, so he simply answered, "Observations."

When he didn't elaborate, Levi asked, "About?"

The boy went back to writing and said, "Well, about you, for the most part. Like, on this page, I'm making a list of your different vocalizations, and writing next to them what each of them mean, based on what I've learned from being around you."

When he glanced up at the Levi, the mermaid was saying, "Because that what you learn…ing?"

Eren smiled hugely, pleased by how well he was signing today. "What I'm studying, yes. I came here to focus on dolphins, but really, I was hoping I'd get to work with you, even before I knew who you really were."

The boy watched his eyes flicker down to the notebook page, watching the fascination spark in them. "What more you write?"

"Well," Eren flipped back a page, "I've also made notes on some of your little behaviors and quirks. Like how you love it when I pet you, how you prefer salmon and trout over tuna. How you're very neat and orderly with the things in your tank and how the rocks have to be positioned a certain way, how you keep the outside and I assume the inside of your cave very clean. How you love the shiny rocks versus the dull ones. And of course how clingy you are."

Levi made a deep, rhythmic, almost metallic kind of rumbling sound in his chest. Eren stared at him oddly for a moment, before he realized, judging by the smile on his friend's face, that he was laughing. It was the first time he had ever heard Levi laugh before, and before he knew it, he found himself grinning widely in delighted surprise. He rushed to write down this new sound on his list, and Levi watched him with amusement.

"What else you see about me?" Levi asked when Eren looked at him again.

"I've also noticed that ever since you learned to sign, you call me a brat a lot," Eren pointed out.

"You are," Levi signed with a snort, "Big brat. Act like little."

Eren stuck his tongue out, and Levi pointed at him, letting him know that he was only proving his point. Eren laughed, pushing Levi's hand down, and the mermaid laughed again, that metallic rumble quieter this time.

"But really, you can't be that much older than me, if you even are," Eren said. "How old are you anyway?"

Levi just shrugged his shoulders. Immediately, Eren felt foolish. Of course the mermaid had no idea how much time had passed since he had been captured. He might not have been keeping track of time before then either. But still, it couldn't hurt to try and figure it out.

"Well, how old were you when were captured?" he asked.

Levi answered quickly with, "Twelve."

"Ah, okay, so that makes things easier. Thirteen years have passed since then, so that makes you…twenty five. Oh, so you are older than me. But not by much."

Levi blinked a couple of times as he absorbed this information. More time had passed than he had thought. In the park, the days all seemed to blur together in one, monotonous stretch. He didn't have the rhythms of the different migrations he and his mother went on in the ocean to help him keep track of time anymore, so it was impossible to know, besides the subtle changes in his body, that the years were passing at all. He couldn't believe that he was this old already; in his mind, he had still been a very young teenager. But now…

Shaking off the surprise, he asked Eren, "How old you?"

"Twenty two," Eren told him.

"See? Brat."

"Yeah yeah," the boy grinned, before quickly writing down what Levi had just told him.

The mermaid was in the middle of explaining to Eren that he and his mother kept track of the years by how many times they travelled up to the Arctic with the humpback whales to join in on their winter feeding, when they heard the sound of footsteps clicking against the stone path that led into the middle of the tank. Almost immediately, Levi sat up and curled around Eren protectively, growling low in his throat and glaring at the intruder over his friend's shoulder. Eren turned his head and looked over his shoulder as best he could in his restrictive hold, feeling relief when he saw it was only Hanji.

"Hey," he greeted over the sound of Levi's growls, which only got louder the closer Hanji came.

"Hello Eren," she said, and added, "Hello vicious beast attached to Eren."

The boy snickered, reaching up rubbing between Levi's shoulder blades. The mermaid was clinging to him very tightly now, on the verge of restricting his breathing, and he chastised, "Levi, manners. You know her, she's not going to hurt either of us."

"You never know," Hanji joked, "I've been told I'm quite the monster when it comes to fighting for the last donut in the box."

Eren snorted, while Levi simply snarled louder, taking her words as a threat. Hanji held up her hands in surrender, and Eren reached up further to start massaging the tense muscles at the back of Levi's neck, shushing him.

"Oh hush. Hush," he murmured, "It's alright, she wasn't serious. We're safe, alright? You can let go."

At that, Levi's growling began to die down. However, he kept Hanji in his sights as he deliberately rubbed the side of his face against Eren's, like a cat, before he laid back down in his lap, turning his back on the scientist. However, his back remained stiff, his body obviously still on alert, just in case. Eren shook his head at him, before twisting his upper body around to face Hanji as best he could.

"So what did you need?" he asked.

"Oh, just to tell you that it's almost lunchtime, and I think you told me you wanted to type up those notes before lunch, yes?"

Eren cursed softly to himself, and then said, "Alright, thanks, yeah, I'll be down in a bit."

Before he could move an inch however, he heard a pitiful whine from his lap that cut off as soon as Eren looked down at the source, as if he wanted to cover up the fact that that noise had in fact come from him. Eren laughed softly and squeezed the mermaid's shoulder. "Oh, you poor thing," he said sympathetically, "It's okay, I'll be back. I'll come and have lunch with you in a bit, okay?"

Levi shrugged, as if he didn't really care one way or the other what Eren did, even though the boy knew that was a complete lie. He leaned over him and bumped his forehead gently against Levi's temple, which allowed Levi to begrudgingly crane his neck up and brush his temple against Eren's once more. He let the boy get up without so much as a single complaint, watching as he brushed off his pants and joined Hanji, waving at him one last time while Levi watched them go, feeling something in his chest deflate just the smallest bit.

Once they were down the ladder and on the way to the lab, Eren heard Hanji start snickering beside him.

"What?" he wanted to know.

Her giggles died down, and she finally said, "Oh nothing. You two are just cute, that's all. It's amazing how much you have Levi wrapped around your finger."

Eren raised an eyebrow and said slowly, "Um…no I don't? What do you mean?"

Hanji looked over her glasses at him. "Eren, sweetie, listen. Do you really think Moblit or I or anyone else in the entire aquarium would be able to get him to do anything by simply asking him nicely? You've got a special way with him is all I'm saying."

The boy shrugged, and blushed slightly at her comments. "But I didn't do anything."

"You're right," she agreed, "You didn't do anything but be yourself."

Eren pressed his lips together, unsure of what to say in response, for Hanji had said this before, and he still didn't know how to react to it. Hanji on the other hand, as she held open the door to the lab and let him go before her, knew exactly what she was on about, but didn't feel that it was the right time to reveal such information. After all, she had a strong suspicion that there was a very specific reason as to why Levi was so eager to obey Eren, if that longing look he had fixed the boy with as they had left the tank had anything to say about it.

But again, it certainly wasn't her place to say anything. Eren would just have to figure it out on his own.

000

True to his word, Eren returned to the tank an hour later, notes typed, with both his lunch and Levi's dangling in each hand at his sides. As soon as he heard the sounds of the boy's footsteps against the stone path, Levi appeared at the edge, exhaling explosively and letting out enthusiastic little chirps upon seeing who it was. Eren couldn't help but smile and laugh.

"Hey there kid," he greeted, "Hungry? I'm starving, so let's not waste time, yeah?"

He settled himself on the edge of the platform, crossing his legs in front of him, and setting down their lunches: a bucket of fish for Levi and takeaway from the seafood restaurant down the street for him. He handed Levi his first fish, before he bothered to unwrap his lunch and take a bite out of it. They kept this up for a few minutes, Eren making his way slowly through his lunch while keeping an eye on Levi, tossing him a new fish every time he reduced the one in his hands to bones and taking the bones from him, tossing them in the bucket.

Levi finished his lunch before Eren did, leaving him to watch the boy eat. Eren had just taken a bite out of one of his fish fingers before he noticed. He stopped mid chew, wondering what on Earth the mermaid was staring at.

"Can I help you?" he asked jokingly.

Levi seemed to realize what he was doing then, and hastily dropped his eyes with a blush. Eren breathed a laugh, and then asked, "What, are you still hungry?"

The mermaid shrugged. Really, his stomach was too full for him to really consider himself hungry. But Eren, being as kind as he was, swallowed his mouthful and then offered one of his fish fingers to Levi, holding it out to him. "Here, this is fish," he said, "It's cooked though, so it'll taste a little different. You can try it if you want, or I can sneak you some more sardines from the back?"

Levi hesitated, sniffing the offered treat carefully. He froze for a moment as he processed the smell, deciding that it didn't smell bad, per se, just different than what he was used to. It did pique his curiosity though, and Eren was kind enough to offer some of his own food to him. Besides, if his friend was eating it and offering it to him, then it had to be safe. So, he took the fish finger from him, and, after he sniffed it one last time, took a small bite, and chewed very slowly, letting the flavor wash across his tongue.

And his eyes immediately lit up.

Eren watched as his friend began to chew faster, swallowing his bite, and then finishing off the fish finger within three more bites. And as soon as he had licked his fingers clean, he was looking up at the boy with the same eyes Fern did after he gave her a chip from his plate.

"Good, huh?" he said with a grin, "Want another one?"

Levi nodded eagerly, and accepted the second fish finger, devouring it much more quickly than the first one, enjoying the crunchy, buttery texture, both flavors foreign to his tongue. Cooked fish was also completely foreign, but it was good, much easier to chew. No wonder Eren had such small teeth and jaw muscles. With food like this, he didn't need the bigger teeth and jaw muscles Levi and his kind had. In an instant, after licking his fingers again, he was pawing at Eren's knee again, his eyes huge and shining.

"More?" Eren prompted, and when Levi nodded, he quickly gave him another one, snorting at how enthusiastically he took it from him. Once that one was finished, he asked for another, then another, and another, until half of Eren's fish fingers were gone.

"Alright you, that's enough for today," he finally said, batting Levi's grasping fingers away. When the mermaid deflated with a morose groan, he added in a stage whisper, "I'll bring you your own portion tomorrow."

Levi brightened up considerably at that, smiling widely and straightening up in the water. Eren decided that he should finish his lunch quickly, as it was already almost time to go, and he took another swig of his tea in his thermos. He felt Levi's curious eyes on him, and when he put the thermos down, he heard the mermaid click questioningly.

"It's tea," Eren explained. "Hot tea. For some reason I thought it would be a good idea even though it's hot as balls out. Although it's slightly cooler by the water."

Before he could take another sip, he took in Levi's longing stare, sighed, and relented with, "I'm guessing you want to try a bit of this too?"

Levi shrugged noncommittally, trying not to show how excited he was at the prospect. He could only imagine that if the fish fingers had tasted wonderful, the rest of Eren's lunch had to be just as amazing. But Eren saw right through him, of course, saw how he was just barely keeping himself from vibrating with excitement, and he rolled his eyes good naturedly. He then leaned over, holding his thermos out to Levi.

"Be careful," he warned, "It's pretty warm, and it'll spill, so drink it slow."

Without a word, the mermaid carefully took the thermos, heeding Eren's warning and holding it with both hands, before lifting it to his lips and tasting it carefully. The heat certainly took him off guard, causing him to startle and almost drop the thermos. After all, he had never eaten something this hot before. Warm certainly, but not hot. But his curiosity won out, and he went back in for another taste.

And as soon as the rich flavor of the tea hit his tongue, he knew in an instant he'd be willing to sell out his best friend to the devil if only he'd be allowed to drink this stuff every day.

Eren watched as he tipped the thermos back further and began to gulp down the tea more enthusiastically, seeing that his cheeks were dusted pink, could have sworn he heard a soft moan escape the mermaid's throat, and realized fondly he was going to have to make room in his bag tomorrow for another thermos in addition to the fish fingers.

000

Later that night, Eren was glancing at the clock, already preparing himself for the horrid time he knew he would see. Sure enough, the numbers were glowing one forty one at him. And he had been laying there for three hours, unable to find even a wink of sleep.

He knew why, of course. He was so tense, his throat, abdomen and shoulders were exceedingly tight, his back felt hot and cold at the same time, and if he closed his eyes for too long, he could feel a headache developing. He was straining his ears without him realizing it, constantly opening his eyes after closing them and looking towards his doorway, or his window, or towards the dark corners in his room to see if something was there. Or worse, eyeing his phone to see if it was going to have a new text message on it.

He had discovered that he had gotten yet another handful of them from him when he had opened up his phone after getting out of the aquarium. He was so engrossed in his work there that he rarely if ever looked at it during the day, and he didn't feel safe having it near the water anyway, so his messages tended to pile up. So it was quite the shock after his wonderful, productive day, to see his ex's name appear in his inbox. His messages ranging from apologies to threats saying he was going to fly down there and teach Eren a lesson as to what happens to people who try to leave him had promptly thrown an icy bucket over his perfect day. It had set him on edge, and to his horror had begun to bring forth old habits that he had been trying so hard to break.

That evening, he had found himself unable to eat anything but a thin, weak soup and a large cup of water, too scared to consume anything with too many carbs, and then insisted that he go for a run after dinner, saying it was to clear his head. He even took Fern with him for good measure, and while she had loved the run, even she seemed to sense something was amiss, constantly looking over her shoulder at him as she galloped along. When he got home, he caught himself staring at the floor, too nervous to look anyone in the eye. He had also been too afraid to say anything much, and had remained uncharacteristically quiet, much to his parents' dismay. He tried to tell them that he was fine, but of course they didn't believe him.

And no here he was, trying to fend off yet another panic attack as he realized how late it really was and how long he'd been lying awake. He was tired, he really was. He could feel the desire to sleep gnawing at his consciousness, but his fear was much stronger. Fear that Reiner would do as he claimed and show up at his doorstep, ready to do him and his family harm. The boy shuddered anew. What would he do if that happened? He didn't even want to think about it.

Eren sighed heavily, trying to both soothe his nerves and expel his frustration. However, he accomplished neither, and he was running out of options. He had half a mind to go out into the living room and watch t.v until he fell asleep. The silence was beginning to unnerve him, and the worst part was, before Reiner, it never had before. It used to be that he could sleep just fine in the ringing quiet, even preferred it, but now he was finding that the absence of sound made it so that he was constantly on alert for something to break it. Like the sound of a door slamming open or-

He shut off his train of thought. He couldn't take this anymore.

Eren sat up and turned on his lamp, before he lowered his head so that it was between his knees. He felt dizzy and sick, his heart pounding too hard in his chest, which only aggravated his growing headache. He groaned softly, both in pain and lingering unease, missing the days when all he had to do to fall asleep was lay down and close his eyes. He contemplated texting Mikasa, but what good would that do? All she would do afterwards was get worried about him, and get on his case about reporting Reiner again, and he didn't have the energy to deal with that.

Maybe his mom wouldn't mind if he borrowed Fern for the night to lay on his bed. But his dad wasn't there right now, working the night shift at the hospital as he was, and while he knew she would understand and would be fine letting him borrow her dog, Eren would feel bad, as well as not feel safe doing so. After all, Fern was to remain in her room with her while she slept, just in case. But why did he even want Fern or Mikasa in the first place? It was like there was something pulling him, but in what direction and for what reason he didn't know. The desire was there though, hot and uncomfortable, the desire for…something.

Eren swung his feet over the side of his bed, feeling restless as he tried to figure out what it was his subconscious was telling him he needed. His feet were leading him across the room, and before he knew it, he was standing in front of his dresser. He blinked down at it, finding that he was looking at his little pile of conch shells, as well as his pendant, which he often laid on top of the one of the shells when he took it off for the day. And he found that even just looking at these shells, seeing the physical evidence of the happiest summer of his life, eased the pounding of his heart and head just slightly.

Before he could stop himself, he was picking up one of the shells and taking it back to bed with him. Once he laid down, he held it up to the light, watching it shine through the thinner parts of the shell. He had been so convinced at the end of that summer that he would never see Levi again, and yet against all odds, they had found each other again, and had somehow grown even closer now than they had then.

Eren sighed, but this time it was a sigh of fondness. Just thinking about the mermaid had a calming effect on him. His muscles began to loosen when he thought of how Levi brightened up whenever he saw Eren come into the tank, how he purred when Eren petted his soft hair, and all of his little mannerisms that never ceased to endear him to him. His happy chirps, how he liked to sleep in a ball, the little crease that formed between his eyebrows when he was thinking hard or concerned, or how his smiles were mostly smirks, but when they turned genuine, they were always for Eren only. The boy felt his muscles loosening one by one as he ran his fingers over the shell, especially when he reminded himself that tomorrow (or later today, he supposed) he was going to have to pack an extra tea for his friend and some extra fish fingers too. Maybe he could even find something else that Levi might like to try. How well would he be able to handle human food? They would just have to experiment and find out. And tomorrow they would keep going on more complex sign language phrases and oh he had planned on telling Levi some more of his past work in his budding career as a marine biologist, maybe Levi would have some insight for him as to how he could improve-

And that was when it hit Eren. Right there, in that bed, was where the answer to the riddle appeared right in front of his eyes. His fingers even stilled on the shell as he figured out why he was so restless. Most of it was just anxiety, but that longing he hadn't been able to put his finger on was there as well, raising its little head and attacking his chest with a vengeance once it had been acknowledged and realized. Eren was feeling lonely, terribly so. But it went far beyond that.

He missed Levi.

The boy huffed. What a ridiculous notion. He was going to see his friend tomorrow, in less than seven hours in fact. How could he possibly miss him? He already saw him every day, practically. Was that not enough for him?

It slowly sunk in for Eren that no, it wasn't. Instead of this shell, he wanted Levi here beside him. The mermaid was such a good snuggler, so ridiculously soothing with his presence. Eren felt something in his chest open and it became a little easier to breathe when he remembered the sensation of Levi's arms around him, holding him against his body and forcing his face to hide in his shoulder, remembered his musky, clean smell. Remembered his soft, sweet croons pulling him out of his panic like nothing else had been able to…

…remembered how safe he felt when he was with Levi.

Eren groaned and buried his face into his pillow. How strange was it that he felt safer in the tank of the most dangerous creature at the Sina Aquarium but not in his own home? But he did. When he felt those strong arms around him, heard that soft voice, he felt like nothing could harm him. Levi wouldn't let anything get to him. And as awful as it sounded he found the idea that he had killed before to be morbidly comforting in this situation. It meant that if Reiner somehow ever got near Eren while Levi was with him, the mermaid would have no holds barred about attacking him with everything he had.

And more than anything, Eren wished he was in the tank right now. He wished he could somehow sneak into the aquarium and spend his night with his friend, for he knew he would sleep far better on those stones if thsn in his bed if he had his guardian watching over him.

But for now, all he could do was grip the conch shell close to his chest, and long uselessly for things that could never be. Levi could never be there to protect him all the time, and anymore, Eren could never be truly safe.

A/N: Title comes from the song lyrics for "Élan" by Nightwish.