Hey! I had a fun time with this one and hope you enjoy! I based this off of H20: Just Add Water (anyone else remember watching that? who was your favorite character?)

YALL I WAS JUST LOOKING UP THE LYRICS FOR INSPO FOR THE TITLE AND TELL ME WHY WHEN I LOOKED UP H20 THEME SONG LYRICS THIS CAME UP JWEFBIASLJDFKLF

I'm gonna water her crops, huh, huh, huh (Viral pussy hoe, ayy)
I'm gon' make her H2O, out her pussy hole
I'm gon' make her H2O, out her pussy hole
Put some diamonds on my fist, now my wrist too cold
Put some diamonds on my fist, now my wrist too cold

y'all this is canon that at some point Levi finds this song and reenacts it on Eren I don't make the rules

Eren was nervous, really nervous. His foot was tapping the whole way to the island, and whenever Levi asked what was wrong Eren simply smiled, even though it was strained, and said to 'wait'. Truth be told he was about to tell Levi the most insane thing ever told in mankind, and he was pretty stressed about his reaction.

Levi, being the bestest boyfriend of all time, kept trying to reassure him in small ways. As he steered them to Mako Island, his hand would periodically lean over and tap his shoulder or leg. He would also lean down and kiss his cheek or nose, giving Eren that adorable there but not there smile that just barely pulled at his lips. Eren loved that smile. He loved Levi, so the thought that the news he was about to share could change how Levi feels for him too was absolutely gut-wrenching.

Eren tried not to show it, but he has had at least 3 panic attacks about this very moment, going over the worst-case scenarios in his mind until he threw up. Armin and Mikasa were nearby, waiting for their cue should it go south, should Levi decide that this secret was too much. They had originally begged him to not say anything. They had made a promise to never tell another soul after all, but it was starting to affect his relationship. He felt Levi getting more and more distant the more Eren turned him down to go to do this or that. Whenever Levi asked him to go surfing, what used to be their favorite pastime, and he had to decline each time, he saw the look of confusion and sadness in his beloved's eyes. Levi never knew the real reasons and Eren could barely provide them. He couldn't allow it any longer. This will be the biggest obstacle they ever had, and Eren was about to face it head-on.

They walked through the jungle, Eren following the well-worn path under the watchful eye of the moon. In only a few days it would be the full moon, the most dangerous time for him, Armin, and Mikasa. He managed to convince his two best friends that with Levi on their side, they would never have to worry about a full moon ever again. They eventually caved, knowing how horrible Eren felt about keeping such a big secret from the love of his life. Levi was silent, seemingly understanding that this was important to Eren and wanting to let him lead the way. Eren loved that about him, he was so kind and observant, always wanting what was best for his friends and family. Always willing to hear them out and lend an ear. Eren found the hole he fell into that fateful day 3 months ago and stared for a moment. This hole irrevocably changed his life, for better and for worst. He huffed and looked over to his boyfriend, winking at his confused expression and jumping in. Levi called out to him, clearly confused at his sudden disappearance but sure enough as Eren was dusting himself off Levi arrived behind him.

"What the fuck? Why the hell is there a slide here?" "No idea." Eren answered easily, moving further through the hall until he entered the large chamber. The dirt floors lead to smoothed walls, no doubt eroded due to past flooding. The ceiling had an opening at the top, leading all the way up to the tip of the mountain they stood beneath. Through it the moon shone brightly, its brightness lighting up the cave so they could see without lighting the torches that lined the walls. But what made it magical was the pool. Smooth rocks lined the crystal blue water with a light seemingly shining within reflecting the moon on its calm surface. Eren stood beside the pool, admiring the water. He could make out the tunnel that led out into open water, just big enough for him to swim through, but much too long for a human to swim. This will either make or break me. This damned water… really fucked me huh? With a sigh, he stripped his shirt and pants off, blushing and laughing when he heard a wolf whistle from behind him. Levi leaned up against the wall, looking at him like he wanted to eat him.

"Is this why you brought me here? Wanted to go for a skinny dip?" He asked, silver eyes gleaming in the moonlight. Eren was quickly reminded why he brought his boyfriend here, his small smile quickly turning into a strained one as he quickly took off the rest of his clothes.

"Eren? Seriously, what's wrong? You've been quiet the whole way here." Levi asked, moving forward and putting gentle hands on his beloved's bare waist. The brunet leaned into the embrace, letting out a shuddering breath when Levi's ripped arms immediately wrapped around his torso and pulled him into his muscled chest. He is so hot. Fuck.

"Do you know where we are?"

Levi remained quiet for a moment.

"… we're at Mako Island."

"True, but specifically we are here, at the moon pool." Eren murmured, gazing at the water that seemed to pull at his very soul to jump in.

"Ok… a moon pool. Never heard of it. How did you find it?"

"Remember 3 months ago when me, Mikasa, and Armin wanted to come out here for a night to sleep under the stars?" Eren asked, turning around in Levi's arms to get a better view of his expression. His eyebrows furrowed but he eventually nodded.

"We found this pool while we were here." Levi was clearly confused about where this was going, simply staring into Eren's eyes as if he could find the answer himself. Eren sighed again, eyes lowering.

"My life changed that day, Levi. I've wanted to tell you since the moment I realized but… I just… I keep thinking that maybe if I did you wouldn't… want me anymore-" Eren started to explain but was quickly cut off by Levi grabbing his hair and yanking downwards, lips colliding in a wet kiss. The warmth filling his heart left no room for worry, so he simply enjoyed Levi's pale lips against his. After a minute, Levi finally pulled back, moving Eren's head until he looked directly into his eyes.

"Eren, I've been in love with you since I was 9. You are it for me. I cannot and will not settle for anything else. We've been dating for 4 years, what could you possibly think would turn me away from you?" Levi asked, eyes searching his. Eren wanted to melt, never getting tired of Levi's I love you. Because of his past trauma, saying 'I love you' has always been hard for him. He usually showed his love in smaller gestures, so Eren knew those moments where he said it out loud were something to be cherished. Eren was silent for a moment too long, allowing Levi's mind to spiral into the possibilities.

"Are you… cheating on me?" The hurt was evident in his voice, eyes giving way to the pain he would feel if it was anything other than a resounding no.

"Of course not! No, I… I love you. I don't even find other people attractive anymore." Eren quickly responded, happy to see the tension quickly leave Levi's shoulders.

"Then what the hell else could you do? If you killed someone, you know I'd help you bury the body. You could kill me and I would thank you for the honor." Levi teased, tickling Eren's side a bit just to see him smile. Eren gave himself that moment to just feel Levi, to enjoy his strong arms and beautiful eyes. I love this man so much. He stepped away, naked skin on display as he walked to the edge of the pool.

"I'm not gonna bother just telling you. You'd never believe me anyway. No sane person would."

This of course only confused Levi even more. He didn't let Levi speak though.

"I'm going to show you, instead. Then… then I'll answer any questions you have."

He took a breath, and then a second one, feeling his heart beating like an erratic butterfly.

He loves me, we'll be fine. He loves me, we'll be fine. He chanted, closing his eyes and swiftly diving into the water.

He watched with concern as the love of his life dove into the water, confused and worried at the cryptic way Eren was talking. What could he possibly think would make me want to leave him? My very reason for existing? The reason I wake up and work hard at school? Levi never cared about school, never cared if he passed or failed. Why should he? He was gonna end up in the gutter, that's what every adult told him. He had no reason to doubt it. No dreams, no aspirations. he gave up on life, simply surviving each day.

Then Eren came into his life.

This young kid saw him on the side of the road, covered in bruises and eating a stale piece of bread. He stopped and stared for a moment, Levi ignoring him since he was used to the looks, but then Eren held out a hand. Levi thought he was trying to take his food and hit his hand away on instinct. That didn't stop the kid from smiling, keeping his hand out for him.

"Wanna be friends?"

And they were. He took Levi with him everywhere, the mall, the coffee shop, and toy stores. They were inseparable. He taught Levi how to surf, and through the crash of the waves, Levi felt his soul just a bit more each day. Levi barely went home, instead, he lived in a large shed behind Eren's house that the Jaeger's happily gifted him. He barely saw his uncle, and when he did Eren was by his side, holding his hand all the while.

Levi loved him, with every part he had. So what did Eren think could possibly change that?

He waited for the brunet to surface, watching as a concerning amount of bubbles rose to the surface. What the fuck? He charged forward, about to jump in as the bubbles began to clear when suddenly Eren's head broke the surface. He relaxed watching with a smile as Eren moved to the edge of the pool, anchoring himself on the smooth stones lining it.

His wet hair framed his achingly beautiful face, the long brown strands curling in a way that made Levi want to play with it. Levi was about to lean forward to do so, remembering Eren had once given him blanket permission to touch his hair whenever he wanted to. However, as he kneeled down to be closer he noticed something odd in the water. Something large and orange was floating behind Eren.

A tail.

"Eren! Get out of there! There's something-" Levi started, grabbing Eren's arm to pull him out, but with the new vantage point he saw it more clearly. It was a tail alright, but it wasn't on some mysterious sea creature. It was attached to Eren. Levi froze, staring at the tail in both awe and horror.

"Eren… what?" Eren smiled shyly, the tail swaying back and forth as he let himself be more horizontal, the tail coming out of the water.

"I'm a mermaid."

They both were quiet for a few moments, Eren waiting for Levi to react, and Levi waiting for the camera crew to yell 'This is HYC Live and you've been pranked!' When neither of these things happened Eren apparently decided to take the initiative.

"Levi? Are you… ok?" Eren questioned softly, hand tentatively reaching out. Levi grabbed it, eyes glued to the large tail even as he rubbed Eren's thumb with his own. After a few moments, he looked into Eren's eyes, the same beautiful green he was used to. This tail, whatever it was, didn't change who Eren was. What Eren was to him.

"Explain."

"Armin, me, and Mikasa all took a dip in here that day. It's such a pretty pool and the full moon was out so of course we swam in here. The next day when I got home I didn't think anything special happened. Then I took a shower and imagine my surprise when this huge fucking tail took over my legs out of seemingly nowhere." Eren explained with a laugh.

"Armin came over, flipping shit because when he was walking to the store a sprinkler went off and he was suddenly laying in someone's yard with his own tail. The Mikasa came over because when she was at her job she naturally got wet and suddenly was swimming with the otters in their tank. So whatever happened in this pool, it made us into this. Whenever I touch water, I become a merman. Even if it's just a drop." Levi listened carefully, noting each twitch on Eren's lip, realizing that Eren didn't see this… condition as a net negative at all.

"Is that why you've been skipping school when it rains?" Levi asked, chest warming at the large smile on Eren's face.

"Yes! And why I haven't gone surfing with you! It broke my heart watching you go alone. Though to be honest, you never were, I always swam beneath you."

He's been going beneath me? To think he wanted to go so bad he would risk getting caught just to be near me…

"That must be difficult, constantly having to be wary of water." Levi wondered aloud. Eren nodded and groaned, tail slapping the surface in annoyance.

"It's exhausting! Do you know how much money I've spent to get Zeke to do the dishes when it's my turn? I barely have any money to my name because of it. Not to mention everyone thinks I'm depressed because I can't go surfing anymore."

"Wait, do your parents not know?" Eren shook his head.

"We agreed not to tell anyone. I'm sure our parents wouldn't send us to a lab to be tested but, you know my mom. She would probably prohibit me from stepping outside. Mikasa's parents would probably lock her in her room for all eternity too."

"So, you're not… mad? or disgusted?" Eren asked after a quiet moment. Levi then realized that Eren was nervous not because he was a Merman, but because he was worried Levi would hate him. Somehow.

"Eren, I love you. Why the fuck would I hate you for this? As if you having a tail sometimes is something horrible." Eren brightened considerably, tail splashing happily in the water.

"Really?! Thank god! I told them this was fine! They were worried you would tell people and break up with me… and… I kinda was too. It's not every day you find out your boyfriend is a merman." Eren replied, making a face when Levi responded by flicking his forehead.

"Brat."

"Hey!" "Get over here and kiss me already you shit. You had me worried as fuck." Levi ordered, happy when Eren easily leaned forward to meet him. They kissed slowly, Levi unconcerned with time as he tasted the salt on his lover's tongue, the wet strands of his soft hair brushing through his fingers. After a few minutes they pulled away, foreheads touching as they took a moment to breathe.

"Eren… since we're sharing stuff… I have one more question." Levi murmured, not wanting to break the atmosphere but his mind kept spiraling towards one thing as they kissed.

"Of course. Anything."

"Do you have genitals?"

Silence.

Green eyes stared into his, shock and embarrassment coloring his face.

"LEVI!"

"What?" "That's so embarrassing! I thought you were gonna ask if I had super powers!"

"Well do you?" "I do actually!" "Oh yeah? They got to do with your merussy?"

"… never say that again." Levi let out a laugh, pulling Eren into a hug even as he pouted.

"You're so mean! I came out with this big secret and your mind is still in the gutter!" Eren complained, slowly nestling into Levi's arms. "But…"

"Yes?"

"Shut the fuck up I will swim away from here so fast I swear to god!" Eren threatened, but considering he was nuzzling further into his shirt Levi couldn't find it in himself to believe it. He waited a few moments, and sure enough, Eren muttered something into his shirt.

"What was that? I can't hear you little fish." Levi teased, laughing when Eren immediately swatted at his thigh. "Geez, so violent."

"I HAVE A PUSSY OK? FUCK!" Eren shouted, hiding in Levi's shirt once more.

"… what?" Levi was astounded, sitting still as Eren remained quiet in his lap. He has a… fuck. Eren could feel himself harden instantly at the imagery, eyes roaming the back of Eren's tail in search of the hole he now very much wanted to find himself in. Eren seemed to understand where his mind went, no doubt feeling his hard-on right through the black jeans he wore.

"Levi!" He admonished, thoroughly scandalized.

"What? Your ass is literally heaven, imagine what your pussy would feel like." Eren groaned, tail shuddering in the pool.

"So embarrassing. Not now but… eventually. Ok?" Eren murmured, eyes finding his lap. He was so sweet, so perfect. Levi would wait years for that pussy.

"Promise?"

Eren sighed, arms wrapping around his waist, content to merely lay there for a while.

"Promise."

I was so close to naming this 'No Ordinary Girl' lololol I hope you guys had fun! Join me on Twitter if you want to see the art I made for this story! daemonic_nomad
Also I did the drawing before I wrote the story, I remembered that all the mermaids had orange tails and gave him an orange tail too. Tell me why when I looked up H20 for a reference on the moon pool that I remembered they had male mermen in the show, and THEY have BLUE tails. fuck.
EDIT: I caved