I found a siren in the amazon that was interesting to me and I felt matched Eren quite a bit. I'll put the story in the ending notes so as to not spoil it as I took inspiration from her story. This was fun to write I hope yall enjoy!

Levi swatted at yet another stupid bug trying to take God knows what from him. He ignored Hange's screeches behind him about 'not hurting the local fauna' but Levi stopped giving a shit one hour into this hike. Hange tricked him into coming along, claiming they were going to a cenote to relax before going home the next day. Instead, the tour was meant to show a small religious sight deep in the Amazon jungle. He knew Hange loved religion and culture, and Levi enjoyed it too to an extent. But not by hiking through thick flora while mosquitos and flies and bugs that science hasn't even discovered yet keep trying to steal his blood. Stupid shitty glasses and their stupid hike through the middle of nowhere.

"Levi! Indaiá says we are taking a break!" Hange called out. Finally. Levi found a small patch that wasn't covered in large plants by the base of a tree and sat, taking out his water bottle from his backpack. He gulped the whole thing down in record time, groaning at the cold water. He was not built for this climate. Sunscreen only did so much against the unforgiving rays against his pale skin. The sounds of birds screeching and frogs croaking filled the jungle, Levi tuning out the babble of Hange asking Indaiá about their home as he wiped the sweat from his brow. Too hot. How anyone is able to live here is insane.

Between the natural noises surrounding him, his ears picked out a peculiar one. A voice. He looked around at their small group and did a quick headcount. They were all there, this voice was not someone here. He stood and moved towards the sound, careful to avoid roots that threatened to trip him. He didn't think, simply following the enchanting melody that became clearer with each step. The sounds of the Amazon seemed to fade as he focused on the sound of the singer. The voice was young, their gender unclear with the pitch. He followed dutifully, ignoring the warning bells in his mind. What a beautiful voice. Why is their song sad? The sound of running water soon joined the singer, the two seemingly inseparable from one another. He broke through and saw the Amazon river before him. The mighty river rushed past, dark green water hiding any predator that would come for him. The notes changed, the melancholic rhythm turning swiftly into one of joy, then seduction. He looked around, grey eyes desperately trying to find the owner of the beautiful voice. He didn't have to wait long, a sudden break in the murky water catching his eye.

A head slowly poked from the water, long brown hair cascading down past their tawny beige shoulders. Their face was beautiful. Large green eyes stared back at him, set in a long face. Curiously, they had a red tattoo going around their eyes, letting the emerald green stand out more. Their lips were brown, open as they sang to him, calling to him. He obeyed, wading past the thicket of all sorts of aquatic plants. The person, a man from the look of their chest, rose farther out of the water, showing off a multitude of black designs across his arms. A hand reached out, Levi blindly reached for it, entranced at the beautiful man. Levi's fingers touched his, and the man smiled.

"Yîara~" The man sang the final word, slowly sinking back into the water. Levi felt his heart stop, moving towards him desperately.

"Come back! Don't-" Levi couldn't finish, the hand holding his pulled sharply. He was beneath the water before he truly registered what was happening. Air. I need air! I need- Lips found his and his brain silenced.

"Ro… hayhu." That heavenly voice murmured against his lips. A warmth surrounded his body as darkness consumed him.

Levi groaned, a pleasurable warmth consuming him as he fought for consciousness. His eyes didn't want to open, his body ached in places he didn't even think he had. What the fuck happened? An odd slurping noise grounded him, allowing him to open his eyes and feel the damp air around him. A hot pleasure cut through him like a knife, feeling like way too much as he gasped and moaned. He came, mind struggling to catch up in between each burst of cum. He looked down, eyes widening when he remembered what he did last, and who was looking at him now.

Glowing green stared into him, a sinful mouth suckling at his flaccid cock. His pale skin contrasted greatly with the dark tan skin of the brunet. The mouth opened a little, showing off a vibrant pink tongue that was curled around his glands. He shuddered at the sight of sharp teeth, not unlike that of the native piranha. They simply studied one another for a moment, Levi trying to figure out why this gorgeous man was sucking him off in his sleep, while said gorgeous man stared into his eyes as if daring him to speak. After a few moments, Levi decided to break the silence.

"Who are you?" His voice sounded raw as if he had been using it for a while. The pretty man stared, slowly letting the limp dick in his mouth go. Levi cringed at the sensation, both from the sudden cold on his oversensitive prick and also the way the man's hands seemed to gravitate towards said oversensitive prick. A strong hand fondled him, ignoring the groan Levi let out.

"Eren." He said simply, voice rough and accented.

"Where the fuck am I and why are you attached to my dick!?" Levi quickly questioned, moving to sit up but wincing when Eren quickly moved forward, caging him in with his body. Nose to nose the man stared.

"My cave." Now that Levi was more aware, he realized his lower back and legs were both underwater. He looked to the side, seeing that he was in fact in quite a large cave. Actually, now that he could see better, Levi is sure that they were in a cenote. Eren leaned down and kissed his lips, tongue swiping at the seam while staring into his eyes.

"Wha-" Levi tried to question, but as soon as his mouth opened Eren took over, seemingly devouring him with how enthusiastic and spit-filled it was. Levi struggled for a moment but then realized that he was naked in a cenote with a strange man kissing him. Definitely, not the worst thing I've been through. Possibly the strangest though. He tested Eren's grip on his arms, but he felt weak, sore, and oversensitive, possibly from being drugged. A nip to his lip took him out of his mind and he focused on the man on top of him. He was bigger, not that that is much of a surprise, with a lot of muscle tone. Levi could probably kick his ass normally, but in his current weakened state, the best he could do was not piss him off. Sexual assault aside, the experience wasn't all that bad. He clearly came a lot, despite the hot man on top of him he could only feel his dick give a few weak twitches. Eren broke the kiss, a string of saliva connecting their lips in a gross way.

"Name?" Eren asked as one of his hands moved down and once again grabbed his dick, seeming disappointed that it remained flaccid. Levi tried to shoo his hand away, but it only worked long enough for Eren to instead begin to fondle his balls.

"Would you quit it? Fucking brat my dick is sensitive!" Levi admonished, but Eren simply stared. His lip curled into a small amused smile. Levi was momentarily stunned at the brats beauty, mind halting in its tracks.

"Name?" Eren asked again, softer this time, lyrical in its execution.

"Levi Ackerman." His immediate response. Why did I do that?

Eren hummed, leaning down to nuzzle his neck.

"Levi." He sang the word, voice harmonizing with Levi's erratic heartbeat. His cock swelled instantly much to his dismay. What the fuck?! Eren laughed at his expression, hand moving to his cock and stroking it a few times, content just to hold it.

"Oi! Stop molesting me! Why the hell am I here? Did you drug me? Kidnap me? Why-"

"Shh… porangabá." His lips sucked marks down his neck and chest until he finally reached his prize. Levi's poor, oversensitive cock. The groans Levi emitted were loud and strained, his body stuck between the line of pain and pleasure as Eren sucked him within an inch of his life. His hands grabbed onto Eren's drying ones, pulling lightly to get him off. Too much!

"Eren! Stop… don't stop… FUCK!" He came down his throat, going limp as Eren continued to suckle at his head. His hips bucked into that hot mouth, tears forming in his eyes from the overstimulation.

"… please." Levi begged, panting when Eren gave a harsh last suck before sitting up. He crawled forward, moving over his body and gently lowering himself so that he covered the sensitive man. His head found his neck, nuzzling into him until he stilled, his warm puffs of breath against his sweaty skin the only indicator he was alive.

"I don't understand." Levi finally said after a few minutes. His breathing had evened out and his body stopped shaking as much.

"'m lonely…" Eren replied softly.

They lay there for a while, calmly feeling the other's presence as they came down from their highs. Levi shifted a bit, legs cramping from the odd position when they bumped into Eren's legs. Or, what he had assumed were Eren's legs, but the scales he felt were not that of a human. He tried to sit up but Eren barred him from doing so, teeth placed into his jugular as a threat should he move further.

"What is that."

"Don't look." "Eren."

"They fear when they look. No want fear." Eren admitted, pulling his teeth away to instead hide his face in Levi's chest. Levi took this as his chance to sit up and get a clear view of what he was talking about it. His breath hitched. Eren had no legs, but rather a long green tail. The verdant color was a lot like the murky green of the river, mixed in with lighter and darker hues as if painted. He couldn't look away, gawking at the still appendage as realization dawned on him.

"You're…" The word hung in the air, Eren's shoulders tensing.

"No fear. I won't hurt Levi." Eren quickly pleaded, shrinking further into his chest.

"I'm not afraid. I'm just… confused."

Eren leaned back to look at him, confusion and hope in his eyes.

"No fear?"

"No fear."

Eren smiled, the look different then the one before.

"Why would I be afraid?" Levi asked, laying back down and pulling the attractive merman with him. Eren happily snuggled closer, reclaiming his spot at Levi's neck.

"I am a son of Iara. Man fear her, man fear me." Levi remembered hearing something about an Iara, back in the town they departed from. Someone was trying to sell him some sort of charm to 'keep Iara away'.

"Who is Iara?" He asked, chuckling at the affronted sound Eren made.

"Iara is mother of waters. She is first. Eren is fifth."

"First of what?"

"First of water people. She saved me, many moons ago. My brother argued with me, accused me of many things. None were true, but he no listen. He… he try to kill Eren. I hurt. I hurt him too and… it kill him." Eren recounted woefully in that melodic accent of his. "Father heard, people heard, they blame Eren. I try to explain but father not good listener. He demand I die. I drowned. No breathing. Then Iara came then. She made me… 'ype. I lived in water now. She say 'kill the man that hurt you. Kill so they hurt no other.' So Eren killed. Many man die to me. But man learned, no longer come to me. Eren is… alone. It hurts my heart."

Levi listened carefully to every word, heart breaking for the poor brat. This magic shit is wild but, I can see his tail. He has no reason to lie about it. Levi pulled Eren closer, hugging the man close. Eren melted at the touch, grabbing at Levi as if he would disappear.

"Stay." Eren simply said. Levi stilled and sighed, squeezing his shoulders and shaking his head.

"I can't. I have people I love and care about out there. People who would miss me." Levi said softly, heart dropping when he felt wetness on his shoulder.

"Is there no way you could come with me?" Levi asked. Eren sighed and shook his head before suddenly he stopped. He sat up, eyes staring into his with an almost manic light.

"Yîara." Before Levi could respond Eren was suddenly gone, pushing himself back into the water.

"Eren! Wait!" It was too late, his tail sunk beneath the water and the surface stilled, no sign of the merbrat.

"Well shit."

Levi was there for a while, he couldn't tell time but he could look around. He studied the drawings on the wall and admired how they went from crude scratches to artistic figures. Fish and mermaids seemed to be the main theme. Eren had a collection of human things, from weaponry to jewelry, a comb, and even a waterlogged phone. All things he found no doubt. Once he had looked over the entirety of the cave twice he found his clothes, groaning when he saw that Eren had ripped off his shirt quite literally. He was bored, unwilling to try and find his way out when he considered all the predators he knew to live in the river. Black caimans, pythons, piranha, and that was just some of the predators in the water. Even if he managed to get out, he had a high chance of getting written off the census by a big-ass jaguar. He wasn't about to risk being someone's supper. Especially since he didn't know how to get out.

He sat down in the water and sighed when suddenly Eren rose from the surface, an odd chirping noise leaving him.

"My Levi! Iara gift me! Look!" Eren suddenly shouted, jumping onto him in haste so they were both laying on the rock once more.

"Eren-!"

"Look!" Eren insisted, shaking something in Levi's face. Levi grabbed his hand to hold it still. He held a glass bottle of sorts, it was small, no bigger than his palm and filled with clear water.

"A bottle?"

"Yes! Iara, bless the mother, gave me hope! She see my heart and bless me with bottle. Levi go on land, go home. He take bottle and fill it with water from big water. Eren will be in bigger water! Eren go home with Levi!" Eren cheered, wet body practically vibrating against him.

"So if I go anywhere with this bottle and… fill it with water, you will appear?" He clarified. Eren nodded happily, tail splashing about behind him.

"Levi pour out water, Eren come back here." He explained, pushing the bottle into Levi's chest.

"You take?" Eren asked, hope filling his expressive green eyes. Levi gave him a tiny smile and nodded.

"Yes, Eren. I take."

"Levi! This ice cream is good! It's… uh… how you say… delicious!" Eren gushed, chocolate ice cream melting onto his fingers that Eren's pretty tongue was quick to lick up. Levi watched with a smile, glad to share another part of the world with Eren.

They sat in the lake beside his new home, Levi putting all the foods they ate for dinner on the floating dock while he enjoyed this time with Eren.

"Eren," He called out softly, tucking a strand of hair behind his ear when he looked over.

"Che rohayhu."

Eren's eyes widened, nearly dropping his ice cream into the warm fresh water. Then he smiled sharp teeth on display that reminded Levi of the deep bite mark on his neck.

"Levi, che rohayhu."

Porangabá = Beautiful Man
Che rohayhu = I love you
Yîara = Mother of the Waters (other name for Iara)

According to the oral tradition of Brazilian folklore, Iara was a beautiful young indigenous woman in a tribe of patriarchal customs, who developed a talent for warfare and gaining admiration from all of her tribe and respect from her father, the chief of the tribe, but stirred up the envy of her brothers, who decided to sabotage her by murdering her during the night. The legend says Iara knew how to defend herself from the attacks of her brothers and accidentally killed them. Discovered by her father, she took refuge in the woods but was captured and punished for the murders of her brothers by being drowned in the river (some versions orals claim they killed her and dumped her body in the river, blaming the night goddess, Jaci, for her disappearance). Turned into a mermaid upon being saved by the nearby fish on the night of a full moon or by Jaci in some versions, she decided to take revenge on all men by seducing them and drowning them in the river. According to some folkloric accounts, those who survive end up going crazy, or survive with teeth marks on their neck.

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