Mermaid Kiri AU
(Bringing from my main account @theGingerTrekie since I got shadow banned again)

"Mmm" Katsuki hummed, his mind felt like mush and his muscles were so relaxed it was hard to hold on to the side ledge to keep his head above the surface.

Eijiro was rutting against him, growling and moaning ferally in his ear, claws digging into his hips to bring him impossibly closer. Despite his recent orgasm, Katsuki's dick was still painfully hard.

He was so overestimated it was borderline painful, his length was sliding between two… two…

"Ohmygod you have two cocks" Katsuki gasped, feeling them tentatively with his fingers.

Eijiro groaned bucked into his touch "there are no birds here, Katsuki"

"What? No that's not…" he sighed, it was too hard to think. 

"You have /two/" Katsuki squeezed his hand around them and Eijiro hissed "won't fit"

"Shhh mate" the merman's voice made him relax again "I'll take care of Katsuki"

"Ei, I…" the blond's protests dissolved into moans as Eijiro started rubbing against him, whispering promises in his ear that shouldn't have turned him on, but did.

Eijiro rubbed Katsuki's stomach again before snaking his hand between his legs. Katsuki gasped when he brushed past his balls and the merman stilled, watching Katsuki's face intently. Eijiro's fingers felt around blindly, rubbing circles around the blond's entrance.

"Eijiro! /fuck/" Katsuki whined, pushing back against his hand. 

Eijiro stared, his eyes wide, as he pressed one finger past the ring of muscle. Katsuki mewled, toes curling, as the merman thrust his thick finger all the way to the knuckle.

"/Tight/" he sounded surprised. "Katsuki unmated? Untouched?" 

Katsuki flushed and turned his head to the side, crying out when Eijiro pulled his finger out and shoved two inside.

The merman bit him on the shoulder and he relaxed enough for him to add a third finger and start pumping them in and out.

"You're my first" Katsuki said between moans "only you"

"Only me" Eijiro breathed, then squeezed Katsuki so tight it forced the air out of his lungs and let out a low possessive growl "only mine"

Even through the haze of arousal and mermaid venom, Katsuki could see the moment Eijiro's control slipped. The blond managed to suck in a half breath before being pulled under the water.

It was so dark, the only thing Katsuki could see was Eijiro's eyes and the occasional shimmering of his scales. His limbs felt too heavy to fight, Eijiro has a vise like grip on him anyway.

Eijiro's fingers slipped out and Katsuki groaned, an explosion of bubbles flowed from his mouth to the surface. He was pushed against the rock wall, the jagged surface digging into his bare skin as the merman spread his legs and bent him in half.

Eijiro kissed Katsuki, opening his lips with his tongue and blowing air into his mouth. It helps a little, but Katsuki will still need air soon.

One of Eijiro cocks pressed against Katsuki's stretched hole as he sunk his teeth into the juncture of his mate's neck and shoulder. The merman held him with his teeth as his length penetrated him.

If Katsuki could've still felt his fingers he would've grabbed Eijiro tightly, but now his hands hung loosely on his shoulders, bubbles carrying his moans to the surface. Katsuki felt so, so full.

Without the venom in his veins the stretch would've burned, he'll definitely be sore tomorrow, but now he struggled not to inhale as it brushed past his prostate. Katsuki was still so sensitive, it was almost too much. He was sure he was crying as Eijiro bottomed out.

Eijiro pulled out halfway and slammed back in roughly, Katsuki's back scraping against the rocks behind him. He let out a muffled cry but Eijiro just bit down harder on his neck.

Katsuki's lungs ached for oxygen, it was hard to keep himself from breathing. It felt like his head was about to pop. 

"Ei… jiro…" Katsuki exhaled what little remained in his lungs, black creeping in at the corners of his vision.

Eijiro released his shoulder and sped back to the surface, he kept himself buried deep inside as he swam. With a grunt he pushed the entire upper half of his mate above the surface, water pouring out of Katsuki's mouth.

Fighting against his primal instinct Eijiro flipped onto his back, maneuvering Katsuki so that he was sitting on top. The position wasn't physically painful,

but every part of Eijiro's body was screaming at him to drag his mate down to the seafloor and fuck him against the soft sand.

So he focused on his mate's distorted face through the water, how his color had returned to normal as he gasped and sputtered, how he looked down at him with a small smile that Eijiro broke with a roll of his hips.

Katsuki put his hands on his chest, limps barely able to himself up. The merman grabbed onto his hips, grinding deep into his mate and thrusting awkwardly. His mate felt so good around his cock, he longed for his second cock to be enveloped in his tight heat.

Right now it was against his stomach, side by side with Katsuki leaking one.

"Touch me!" Eijiro gasped, taking the blond's hand and putting it on his length "Katsuki touch me!"

Katsuki tried to do what Eijiro asked, he really did, but between almost blacking out and the fact that his fingers were so numb that he couldn't even form a fist, the most he could do was sluggishly rub him with his palm.

He could tell the merman needed more than that, he was thrashing wildly below him grinding his cock so deep that the blond felt like his insides were being rearranged. 

"Ka...tsu...ki…" Eijiro said through gritted teeth, he looked desperate.

So Katsuki did the one thing he knew his venom riddled body could do to help Eijiro, he took a deep breath and pitched to the side back into the water. The merman dragged him to the bottom so fast the blond thought his ear drums would rupture,

luckily it wasn't horribly deep (probably about 25 feet) but Katsuki knew that the rapid pressure changes could be wreaking havoc on his body. He felt Eijiro latch onto his neck again, fitting his teeth back into the same bite mark he made before and started a brutal pace.

It felt like Eijiro was trying to crush Katsuki with his body, the mermans abs brushing against his throbbing length with each thrust. The friction (or maybe the lack of oxygen) had him seeing stars and it didn't take long before Katsuki was cumming again with a distorted shout.

Eijiro let out a frustrated groan and resurfaced, holding his mate upright so both their heads were out of the water. Katsuki rested his forehead against Eijiro's, unable to hold himself up at all.

"'M sorry" he breathed, his words slurred and dreamy, It was difficult to keep his eyes open at this point "making you do all the work" 

Eijiro shook his head and backed up against the ledge, using his arms to bounce Katsuki on his length

"Katsuki's body was not made for this" the merman grunted, pressing a kiss on Katsuki's slack lips "my mate is doing so well. Perfect mate"

Katsuki moaned at the praise, throwing his arms loosely around Eijiro's shoulders. He loved the way the merman made him feel, wanted and loved and warm. No one else had ever really made him feel like this.

Even though his nerves were so over stimulated that it felt like he was on fire, the blond wanted more. More good feelings and praise, more Eijiro. 

"T-tight" the merman whined "Katsuki got tight"

Oh so those muscles still worked. The blond focused on flexing his muscles.

"K-Katsuki?!" Eijiro moaned, his eyebrows knitted together with pleasure and he made a strange sound that sounded like a curse "feels so good. Katsuki's insides feel so good"

Katsuki swelled with pride and continued, relishing in the fact that the noises Eijiro was making. The more the more forced himself to move, the more feeling he got back. The numbness in his limbs turned into tingling and shrunk back to just his finger tips. He could feel the +

Soreness now, the dull aches where Eijiro had been rough with him. Katsuki rolled his neck experimentally, happy that he was able to do simple movements with ease again.

When the tingling disappeared Katsuki grabbed onto the ground behind the merman and took over, fucking himself on Eijiro's cock while the merman stared with a mixture of shock and awe.

"What… what is this?" He gasped, throwing his head back 

"What?" Katsuki smirked, rolling his hips "none of your past mates did /this/"

Eijiro whimpered and shook his head, he reached for Katsuki's hips but the blond slapped them away. He could feel his whole body again. Now Katsuki was ready to take control.

"Then just stay still and take it" he slammed his hips down and Eijiro writhed beneath him "if we were on land I could move better, but for now this'll do"

Katsuki grabbed Eijiro's second cock roughly and pumped him in time with his thrusts. The merman's hands hovered over his mate's body, claws trembling. Eijiro's mind was screaming to fight him, flip him, make him submit, but this felt so good.

He had never had a mate take such an active role. Eijiro cursed in his native tongue, doing his best to stay still like Katsuki wanted. 

"After you finish I can go find Shoto and…"

Eijiro didn't hear the rest of his mate's words. All his mind processed "I can go". His mate wanted to leave… leave the nest. Leave /him/. 

"/NO/" Eijiro snarled, his voice threatening.

He ripped Katsuki of him and forced his mate's chest against the wall. The edge of rocks slammed into Katsuki's ribs, knocking the wind out of him and almost breaking the bones. The blond wheezed, crying out when Eijiro teeth cut deep into the back of his neck.

The taste of metal flooded the merman's senses and he growled, spreading Katsuki's cheeks and lining up again. 

"Wait, wait!" The blond groaned "Ei, wait!"

"/MINE/" he hissed

Katsuki felt both of Eijiro's heads kiss his entrance and he held his breath. The merman pressed forwards and this cocks popped in. Katsuki's mouth opened in a silent scream as he bottomed out. It felt like he was being split in half, his thighs trembled and he struggled to relax

Katsuki was glad that Eijiro was giving him time to adjust instead of immediately fucking him into the wall. The blond felt his tongue gently lapping over the bite mark on the back of his neck, running his fingers lightly down the sides of his body.

Katsuki looked over his shoulder at Eijiro's concerned face. 

"Mate" the merman breathed, leaning in and licking the tears from Katsuki's cheeks "is Katsuki in pain?" 

"Y-yes" his voice was wavering "too much"

Eijiro pulled his hips back and Katsuki screamed, instinctively clamping down until the merman stopped moving. 

"Too tight, Katsuki" he whispered, running the blond's sore back muscles "I am sorry… I didn't mean to hurt Katsuki again"

"I-it's ok" Katsuki was trying to focus on his breathing but it was hard to relax now, especially with Eijiro sniffling behind him. 

He reached over his shoulder and stroked the merman's hair, it didn't burn as badly anymore but moving was still out of the question.

"Is there anything I can do for Katsuki?" Eijiro whimpered against his skin "I want to help" 

"Maybe…" Katsuki chewed on his lip before whispering "Maybe… you could sing to me again..."

Eijiro flinched, the sudden movement making the blond groan "Katsuki I cannot! Never again!" 

"I think it would help" 

"Anything but that… I've already hurt my Katsuki enough" 

"I can't think of anything else"

Eijiro was quiet for a few seconds before slowly rolling his hips, Katsuki yelped and shot him a glare. 

"What the fuck?" 

"Katsuki relaxed more! I thought I could try! It hurts not to move…"

"Yeah I'm sure /you're/ in a ton of pain"

"Katsuki…"

"If I could relax you could start again, I don't want to stop it's just… it's a lot"

Eijiro sighed then took Katsuki's hands and laid them on the ground, placing his own hands firmly over them. 

"Hold on and don't let go" he whispered "please"

"Eijiro…?" 

The merman leaned close to Katsuki's ear and began to sing softly.

The effect was immediate. Katsuki felt like it turned to Jello and his eyelids sagged. The blond sighed and laid his cheek against the rocks, since Eijiro was already so close his body didn't feel the urge to move like it had the last time.

The merman rocked his hips and Katsuki could vaguely feel it, but it felt like it was happening to someone else and not him. The song kept getting interpreted by little moans, until Eijiro stopped singing completely and started thrusting at a steady pace.

"Don't stop" Katsuki mumbled, his voice breathless. 

Eijiro groaned and nipped at his ear as he picked up the pace, lewd noises and splashing sounds echoed off the walls.

"Does it feel good now Katsuki?" The merman panted, taking his hands back so he could grip his mate's hips.

Katsuki hummed dreamily, still in a daze. It did feel better now, Mermen must have magical dicks because the slide is smooth. He really wanted Eijiro to keep singing instead of grunting in his ear.

The merman was getting close, his breathing was ragged and his claws were digging into Katsuki's hips so hard they almost broke skin. Katsuki could feel himself getting pulled down, but his hands were holding on to the rocks keeping him above the water.

Why was he holding on again?

Eijiro pulled out to the tips and changed angles before thrusting back to the hilt, slamming directly into Katsuki's prostate. His eyes flew wide open and he saw stars.

"Oh /fuuuck/" the blond keened, and Eijiro repeated the motion "Eijiro!"

"Katsuki is mine." Eijiro grunted, going impossibly faster "tell me. Say it!" 

"I'm yours! Only yours!" 

"I'm yours" he repeated softly in Katsuki's ear before cumming with a shout.

He felt Eijiro cum inside him and it was a strange and uncomfortable feeling that lasted for almost thirty seconds. The merman practically squeezed the life out of Katsuki, holding him so tight that his thought be heard his ribs creak.

When Eijiro finished he slid back under water to catch his breath and Katsuki scrambled back into land.The blond's skin was wrinkled and his eyes burned from the saltwater. Cum leaked down his thighs and he shuddered at the feeling.

"How long did you say this is gonna last?" Katsuki asked when he heard Eijiro resurface

"Days" 

"Right…" damn it he was gonna die "I need food and water" 

"I will hunt for Katsuki" Eijiro said puffing out his chest

"I can't drink salt water"

Eijiro's smile faltered

"I don't have a phone either, I need to tell my friends where I am" 

"Can't leave. No time. I will care for Katsuki" 

"Right" 

Eijiro swam off leaving Katsuki alone in the dimly lit cave.

"Katsuki… Katsuki wake up, it's done…" 

Katsuki groaned. He felt like absolute shit. After Eijiro had returned from hunting it had been almost non-stop sex. He only stopped to hunt or to let Katsuki eat.

The merman always brought back prepared food that he must have stolen off of ships, luckily always bringing back a decent amount of bottled drinks.

The blond had lost track of time, he couldn't see the sky so there was no way for him to tell how many days went by. He was pretty sure he had blacked out for chunks of it, he was honestly amazed he survived.

His body was achy and sore, covered in a layer of salt, grime, and cum. His head hurt from dehydration and his eyes stung. His throat was dry and there were sores in his mouth from swallowing so much salt water. His skin was so dry it hurt to move.

The blond opened his eyes slowly and looked at Eijiro's bright smile hovering over him. Katsuki blinked a few times, confused.

"You're on land?" 

"I am!"

Eijiro helped Katsuki sit up and he stared at the merman's legs.

It looked like he had sawed his tail in half and it healed that way, there were scales on the outer part but raw scar tissue on the inside and his feet looked like you had wrapped human feet in translucent algae.

It was honestly pretty freaky, especially since Eijiro still had his two cocks dangling between his legs.

"You have…" Katsuki didn't really want to call them legs 

"I do!" Eijiro seemed proud of himself "I can switch between these and my tail easily now!" 

"...huh…"

Katsuki tried to stand but his legs gave out and Eijiro caught him, his head was spinning. 

"I probably need to go to a hospital" 

"A what?" 

"I need to go, Eijiro"

fuck he didn't have pants or a phone… Eijiro sat Katsuki by the water's edge and jumped it, his legs fusing back into a tail before he scooped the blond into his arms.

Katsuki held his breath as he sped out of the cave, the light outside was blinding but it felt so good to feel the sun.

Katsuki wished that Eijiro's heat had ended at night, that way it would be easier to sneak into the beach naked without getting caught… 

"Wait, Ei, where are we going?"

"To the place I got Katsuki's food!"

What? 

Eijiro took him towards the private cove in the Todoroki estate, a single buoy floated in open water.

Katsuki squinted at it, there was a picture of his face attached to it as well as a ice box and a waterproof bag with a fully charged brick phone. The merman helped him float as he opened the ice box and down the two bottles of water,

choking halfway through the second when he swallowed wrong. Then he grabbed the phone. Deku and Shoto must have gotten it just for this, the date and time weren't set and there were only two numbers in the contacts. Katsuki took a deep breath and called Deku.

The phone rang a single time. 

"KAACHAN!" Deku was already crying "we searched for days! We thought you were dead! What happened?!..." 

Katsuki held the phone away from his ear as Deku rambled for the next minute or so.

"I need clothes" he interrupted "and probably a doctor" 

"Right! Right. You're at the buoy? Well come get you." 

"Hurry up, shitty nerd." Katsuki licked his chapped lips "how long was I gone?" 

"What? You don't… Shoto call Fuyumi!"

"Fuck I don't have brain damage" at least he didn't think he did "I was in a cave, I don't know what day it is" 

"Kaachan you've been gone for almost three weeks" 

"THREE WEEKS?!" Katsuki glared at Eijiro "you said /days/ fish for brains not weeks!"

"I kept leaving food for you because it kept disappearing, but we didn't know if you were getting it or not..."

"I got it." The blond sighed, grabbing a snack bar out of the box before muttering "thank you."

Deku and Shoto showed up about twenty minutes later on a small motor boat and Eijiro hesitantly handed Katsuki over. The blond felt dizzy and nauseous, and it didn't help that Deku was so openly horrified by his condition.

Eijiro looked guilty, blowing bubbles in the water while Shoto wrapped Katsuki in a towel. 

"You look like shit" Shoto stated, putting a huge hat on his head to protect his skin from the sun.

"Feel like shit" Katsuki grumbled, too weak to protest when Deku started rubbing Chapstick on his lips while pointing out everything that was wrong with him under his breath. 

Shoto sighed and turned the boat back on.

"Whoa wait… Eijiro?" Katsuki glared over the edge "Eijiro aren't you coming?" 

"Kaachan you can't bring a mermaid to the hospital." 

"We can't just leave him here" the blond hissed. 

Deku blinked and scowled "Yes we can?" 

"No we can't"

"Katsuki, mate." Eijiro grabbed the side of the boat and pulled his head up, causing the whole thing to rock dangerously "I will wait here for my Katsuki"

"Eijiro there's no way anyone will let me come anywhere near water for a while..." Katsuki whispered, his eyes scanning over the bruises he had left on the merman's neck and chest "Come with me."

"Katsuki…"

"Please."

Eijiro sighed and flopped onto the deck, groaning as his tail split into legs again. Deku averted his eyes and handed Eijiro a towel which the merman simply held instead of covering himself with it. He sat down next to the blond.

"I cannot say no to my mate" 

"Damn right" Katsuki leaned his head onto Eijiro's shoulder and yawned "your mine."

"I'm Katsuki's"

Eijiro discovered very quickly that he did not like hospitals. It was full of sickly humans and it smelled of illness and blood. Eijiro was already uncomfortable enough, his mate's "friends" had forced him into restricting "clothes" and "shoes"...

He decided that he hated shoes

The receptionist had panicked at the sight of Katsuki when they walked in and they were rushed back into a small room with gross pictures of human insides on the walls.

Eijiro also decided he didn't like doctors. The strange human in all white came in and started touching /his/ mate. The merman growled and Katsuki shot him a look. He would try not to growl anymore… maybe he should've stayed in the water.

Eijiro didn't get the chance to tell Katsuki that mermaids were typically more aggressive immediately after a heat, a primal instinct to protect their newly impregnated mates. So when the doctor stabbed Katsuki's arm, Eijiro nearly attacked the woman.

Luckily Shoto had been close enough to shove him back in the chair, his thumb digging painfully into the gills in his sides. 

"Is he… ok?" The doctor asked, alarmed, scanning Eijiro's face.

"He has a thing against needles," Shoto responded calmly. 

Eijiro bit his tongue hard as he watched the doctor stab his mate repeatedly, first with a tube in his arm and then around some of the deeper bite marks on his face, neck and shoulder.

"What happened to you!?" She asked as she looked at Katsuki's body under the hospital gown "You look like you were mauled by a shark but the bites are too small" 

There was a nervous energy in the room. Katsuki shrugged "I don't remember"

"You don't- this is more serious than I thought..."

They were moved upstairs into a bigger room with more chairs, a private bathroom and a couch. Shoto picked up a phone to order more food, while Deku called Katsuki's parents to let them know he was alive.

Eijiro was going insane standing still.

"M gonna shower" Katsuki announced, standing on wobbly legs. 

Eijiro was by his side in seconds to steady his mate, the sight of that fine in the blond's arm was stressing him out.

He helped Katsuki to the bathroom, and sat him down on a bench near what the blond identified as "the shower" but to Eijiro it just looked like weird metal high on the wall. There was a plastic container full of orange liquid that smelled nice, his mate called it soap.

It made millions of bubbles that Eijiro rubbed gently over his mate's skin. He decided he liked soap.

"Katsuki I'm sorry" he whispered, crouching on the floor as he cleaned Katsuki's legs "I hurt Katsuki badly" 

"S fine, I feel better anyway" Katsuki pointed at the tube in his arm "I was just dehydrated." 

Eijiro kissed the inside of his mate's knee "I am still sorry"

The blond sucked in a breath and spread his legs a little more, looking away "I said it's fine" 

Eijiro moved a little higher up his mate's leg and kissed him again, pressing his lips against his skin for longer "my Katsuki"

He bit his lip and focused on a random tile on the wall, as he felt the merman's fingers tickle the inside of his thighs. Katsuki gasped quietly, spreading his legs more. Eijiro purred and placed his hands on either side of his mate's hips as he left a trail of kisses up his legs

After all their time together Katsuki was still so sensitive, he was panting looking down at Eijiro with half lidded eyes. Katsuki's length was fully erect by the time Eijiro got to it and placed a kiss on the tip. 

"My Katsuki" he repeated

"E-Eijiro" Katsuki gasped, letting his head fall back against the wall "oh fuck"

The merman took him in his mouth, sucking gently while teasing the slit with his tongue.

After three weeks Eijiro knew what Katsuki liked now, what to do to pull small gasps from him and make him squirm. Now without the burning need to breed, Eijiro could take his time and make Katsuki feel good.

Katsuki ran his fingers through Eijiro's hair and covered his mouth, trying to quiet his moans as the merman bobbed slowly on his cock. The blond knew this was not the time or place to be doing this, plus he had just spent the last /three weeks/ doing this, but it felt so good.

The added pressure of his friends being right outside made Katsuki's heart race and the way Eijiro was looking at him like he was the only person in the world made his whole body hot.

He thrust his hips up into Eijiro's mouth, hoping he would get the hint to go faster, but the merman held his hips down and sucked at an even slower pace. 

"Eijiro" Katsuki whimpered "fuck! /please/"

Eijiro hummed, working him with his tongue as he sped up ever so slightly. Katsuki was going to die, writhing against the merman's iron grip. He momentarily forgot that he was in a hospital shower and moaned loudly when Eijiro took his entire length into his throat.

Katsuki cried out in pleasure when Eijiro swallowed, the tight muscles massaging his cock, it was so hot and tight. He tried thrusting again, legs trembling, but the merman held him still and began fucking his face on the blond's dick.

"Ohmygod" Katsuki screamed, wrapping his legs around Eijiro's back and pushing down on his head with both hands "eijiroeijiroeijiro fuck you feel so good!"

The blond came with a shout, spilling down Eijiro's throat while the merman choked and sputtered. There wasn't much, but Katsuki was surprised he had anything left to give. He let Eijiro go and he popped off with a gasp, his eyes teary and his face red

"Is that how Katsuki feels underwater?!" He asked between coughs

Oh shit, the blond had accidentally choked him. He had forgotten they weren't in the cave anymore, out of the water Eijiro needed his mouth to breathe.

"Shit sorry!" Katsuki said, wiping Eijiro's face "are you ok?" 

He nodded and Katsuki sighed "ok, let's turn the water off and-" 

"WHERE IS THAT FUCKING BRAT?!"

The door flew open, hitting the wall with a loud bang. Eijiro growls and turned, teeth bared ready to protect his mate, but when he saw the woman in the doorway he frowned. It was a Katsuki clone, same hair, face and eyes, but she was older and a woman

She was also wearing clothes like she had just stepped off a cruise ship, hair pushed back with huge sunglasses and a bikini under her crop top. She made a disgusted face at Eijiro.

"Who the fuck are you?" She hissed, pushing him out the way and glaring down at her son "don't fucking tell me that you made everyone think you were dead because you can off with some" she eyed Eijiro again "some /guy/" 

"Mom."

"I swear you made everyone worry for nothing," Mitsuki continued while fusing with Katsuki's hair. Eijiro noticed her hands were trembling.

"You made me and your father think you were /dead/. My grandmother won't stop ranting about a mermaid taking you. Do you know how stressful this has all been?"

"Mom." Katsuki said firmly, pushing her hand away "I'm fine, stop freaking out"

"You have got some nerve" she hissed, taking a step back and crossing her arms "What happened? Where were you?" 

"Don't remember. Can I put some clothes on, hag?"

Mitsuki slapped her son upside the head and Eijiro had to clap his hand over his mouth to keep from growling at her. He didn't understand how humans interacted with their parents and as much as he wanted to attack his woman for striking his mate, he needed to behave.

"That's a load of crap" Mitsuki spat, handing Katsuki a towel "where were you?" 

"I was fucking a mermaid for three weeks" he snarled, drying himself off 

Mitsuki slapped him across the face and Eijiro winced.

"Fine, don't tell me" she said, voice wavering at the end of her sentence "you insensitive little brat"

She left the room and slammed the door behind her. 

"That went better than I thought" Katsuki shrugged, pulling on the hospital gown with Eijiro's help. 

"That was… better?"

Katsuki nodded but didn't elaborate and slowly left the room. Eijiro followed close behind to make sure his mate was ok and to help him back into the hospital bed.

Deku blushed anytime he looked in their general direction and Shoto had headphones in with music playing so loudly Eijiro could hear it. Mitsuki had left.

The hospital kept Katsuki for three days before releasing him to go home. His parents left to continue their vacation shortly after, so it was easy for Katsuki to sneak Eijiro into his house.

~ 5 years later ~

Katsuki waited in his apartment nervously drumming his fingers against his thigh with one hand and feeling the outline of the ring in his pocket with the other. He had been mentally preparing himself for this day ever since Eijiro agreed to stay on land with him.

His boyfriend was going to come home from work and Katsuki was going to propose, then they would stock Eijiro's nest with supplies so the blond could go through Eijiro's heat without almost dying.

Katsuki had been quietly prepping his boyfriend for this too, shoving him romance movies to slowly introduce him to the idea of marriage. Eijiro seemed excited about it, even asking "are we going to do that?" After a cheesy love story.

Katsuki had just smiled as he said "if you want to", but he didn't tell Eijiro that he had already gotten a ring.

He knew exactly what he wanted to say, he had practiced in front of the mirror for weeks. Now his boyfriend just needed to show up. Eijiro was late which was unusual. Katsuki got up and paced around their kitchen, trying to calm himself down.

Maybe he got held up at work. The weather has been awful today so maybe his boat was taking longer to dock than normal. Katsuki checked the time, Eijiro was 30minutes late.

His heart skipped a beat when the door finally opened and Eijiro stepped inside, stripping off his shirt immediately.

"Eijiro I-"

"Katsuki I have to leave" 

The blond froze "w-what?" 

"My heat's coming up, I can feel it" Eijiro sighed, removing his pants too "I gotta go, I'm going crazy"

Katsuki relaxed a little bit and fished the ring out of his pocket "oh that! You mean we gotta go? I got stuff ready for you nest it'll be easier on me than last time we-"

"No Katsuki, just me. I have to go"

"And I'm coming with you. We're mates, we're going to spend your heat together" Katsuki was scowling, following Eijiro to their room. 

"No you're staying here. I can't heat share with the same person twice."

Eijiro said it so casually as if that was common knowledge as he went through his jewelry box and fished out a locket necklace with Katsuki's picture in it.The blond grabbed his arm roughly. 

"What the fuck are you saying?"

"I'll be gone for a month tops" Eijiro frowned cupping Katsuki's face "hey what's wrong? Why are you crying?"

"You're fucking leaving me that what's wrong!" He screamed, pushing Eijiro away "You want me to wait here while you go fuck some random person? Fuck you!"

"Hey hey hey, Katsuki it's not like that!" The merman tried to hug him but got pushed away again "I'll come right back! It's just for me heat then I'll come home"

"If you leave now you won't have a home to come back to" Katsuki hissed "if you go we're done"

Eijiro's face fell "Katsuki it's /one month/! I've been here for five years! I gave up my entire life to be with you! This is the one thing I can't control!"

"Why can't you spend it with me? I spent weeks preparing, I have oxygen tanks and meals ready…"

"I thought you knew." He rubbed his face "Katsuki I can't get you pregnant, I have to go for my heat but I'll come home to you and we can go do whatever you want, we'll take a month just for us, ok? I'll make it up to you"

"No. If you leave then it's over" 

"Katsuki, please" 

"What's it gonna be"

Eijiro looked broken, clutching the locket around his neck so tightly his knuckles were white as tears started to spill over.

"Katsuki, I can't stay" he whispered "but I'm coming back-"

"Don't bother. I'm clearing out your stuff" 

"Katsuki" 

"/leave/"

Eijiro stared at the ground, lip quivering before pulling on a pair of shorts. He kissed Katsuki's forehead, letting out a choked sob and then left. The blond collapsed to the ground and screamed, tears flowing. He grabbed the ring out of his pocket and threw it across the room.

"/FUCK/" he yelled, punching the ground with his fists. 

He wanted to run after Eijiro, but instead he destroyed their apartment, throwing furniture and breaking dishes until he was too tired to stand. 

It took exactly three days for Katsuki to realize just how badly he had fucked up. He had been cleaning up his wrecked apartment, accidentally digging up every memory he had with Eijiro.

He even found the box of courting gifts he had received when they first met, the blond had kept every single one.

Katsuki was a mess. He noticed Eijiro's phone in his discarded pants and opened it to find that his boyfriend had pre recorded messages for him to watch while he was away.

"Hi, my love! If you're watching this it means I've left and you already miss me!" Eijiro flashed a blinding smile in the recording "just know that I miss you too and I'll think about you every day! I love you and…"

he looked around dramatically, "I'm gonna sing for you now. I don't know what it will do since it's a recording so please watch it in our home with locked doors just in case"

Katsuki was crying before but the singing made it a million times worse. He wished it would put him in a trance like it did in person, but instead he just felt an unbearable need to be with Eijiro.

The song was the same one he sang the first time years ago, but now Katsuki knew what it meant. The song was about love, and how with it anything was possible.

There were 30 one minutes videos, one for each day Eijiro thought he would be gone. Now Katsuki knew why he had been so late that day. The blond watched the first three and then cried himself to sleep.

Katsuki spent the next 2 weeks cleaning the apartment, fixing everything he broke and stocking up on Eijiro's favorite foods. His boyfriend had said one month tops, so Katsuki would do everything he could to get ready for his return and apologize for how he reacted.

He watched his videos daily, Eijiro sang in most of them. It was painful. At the three week mark Katsuki took time off work and spent his days on the beach, surfing like he used to in hopes that he could see Eijiro when he came back.

One month came and went… then three more… Eijiro still hadn't shown up. Katsuki waited on the beach, skin getting tan and hair sun bleached like it was when he was young. He didn't know what else to do, he had no way to contact Eijiro.

"Kaachan, it's been six months" Deku sighed, sitting down in the sand next to him "I think you have to accept that he's not coming back" 

Katsuki looked at Deku, who was offering a sympathetic smile, and punched him square in the nose

Katsuki didn't start losing hope until the one year mark. He was sitting alone on the beach, listening to Eijiro's singing on his phone on repeat. Listening to mermaids' songs on repeat probably wasn't good for his brain, but he couldn't help it.

It was the only thing that made him feel better, and he found that if he listened enough times the magic would work. The song Eijiro was singing was about going home to your lover's arms. Katsuki had listened so many times that he could finally feel himself slipping under.

He felt his body stand up and start walking towards the water on its own. It felt like Eijiro was so close. 

Katsuki got one foot in the water before he was talked to the ground. The wind was knocked out of him and the fragile trance he was under broke. 

"What the fuck?"

"Bakugou you've done so many stupid things but I'm not letting you kill yourself" Shoto hissed before slapping him across the face "pull yourself together!"

"I wasn't! I was just…" Katsuki frowned, he actually didn't know what he had been doing "What the hell are you doing here anyway?"

"Right…" Shoto stood up and then helped Katsuki "I found Eijiro" 

"What? Where is he?"

Shoto shifted unfortunately before pulling out his phone and showing it to Katsuki "My father has him"

~ 9 months earlier ~

"I'm pretty sure kidnapping is illegal, bro, can you let me go?" Eijiro called banging on the glass of the giant aquarium he was in "or can I at least have a board game? Hello?"

He groaned in frustration and sunk to the bottom of the tank with his arms crossed. It had been almost a month since he got captured. It had been really stupid in Eijiro's part. He had been on his way, arms full of apology gifts for Katsuki.

The merman had been so distraught after he left that he never found a mate and ended up spending his heat alone.  Eijiro spotted a familiar looking boat and thought it would be easier to catch a ride with Shoto so he resurfaced.

Shoto wasn't on the boat, but a huge man with angry blue eyes and a weighted fishing net.Eijiro managed to hold on to the gifts but got taken. 

Now he didn't know where he was, probably in that guys house, sitting alone for days on end.

Thankfully the tank automatically cleaned itself and food would appear every few hours.

He'd pass the time by blowing bubbles or stacking his gifts for Katsuki, but that got boring really fast. Whenever the man showed up Eijiro would talk his ear off.

"Dude even if you don't think in a person this is animal cruelty" Eijiro whined, floating belly up dramatically "I'm dying here."

It took 3 weeks of complaining before the man set up a TV for him and threw in a handful of dog toys and a rubix cube. Eijiro finally learned the name of his captor from watching the local news.

"Millionaire Enji Todoroki said to be back at his main estate for…" Eijiro tuned out the rest because he didn't care, but hey now he knew he was in Todoroki's house! He just had to wait until Shoto visited home and he would clear everything up!

Eijiro tried to ask Enji about his son but that seemed to make him extremely upset. That was not the reaction the merman wanted… he would have to think of another way to break out.

6 months in and Eijiro was miserable. He had solved his rubix cube more times than he could count and chewed through all his toys out of boredom. Enji had scolded him and said he wasn't getting him anymore.

He was on the verge of pulling his own hair out when a familiar face on the news caught his eye.

"Local fashion icon Mitsuki Bakugou's son seen staring at the beach staring at the sea for days at a time… is Katsuki Bakugou on the verge of another mental breakdown? More at 8" 

/Katsuki/

Eijiro pressed his face against the glass, straining to see more details. The video said "live" in the corner and showed Katsuki's back as he stared out at the ocean, then Deku appeared on frame walking towards him. Eijiro growled instinctively.

The green haired man sat down next to his boyfriend… ex boyfriend… and started saying something. They were too far away to hear the audio, but apparently whatever Deku said pissed Katsuki off because the blond punched him right in the nose.

There was a grotesque crack and Deku fell to the ground holding his face. 

"HE'S GONNA COME BACK, SHUT THE *beep* UP, DEKU"

Katsuki was waiting for him.

Eijiro screamed and banged on the glass with his head. 

"IM HERE!" he sobbed "Katsuki, I'm here, I'm here, I'm sorry!"

He sunk to the bottom of the tank, watching his mate get arrested on live television. The cops had to physically tear him off of Deku.

"Katsuki!" He hit the glass again "This is all my fault! I never should've left" 

Enji walked into the room with a scowl "what's all the noise about? Fish are supposed to be /quiet/"

"Let me out!" Eijiro yelled "he needs me! My mate needs me! Let me go!"

Enji raised an eyebrow "your mate, huh?

Eijiro was exhausted, he neck hurt and his fins ached. Enji was determined to get the merman to lead him to his "mate", so he would attach a collar around his throat and set him out in open water.

"I'm not an idiot you know" Eijiro hissed

Enji grabbed his by the collar and lifted him out of the water like he weighed nothing.

"You /will/ take me to your mate." He growled, shaking the merman roughly "it's a win for both of us, you will have someone to play with and I will have a new business venture"

Eijiro was forced to "search" day in and day out for months. By the time Enji put him back in his tank Eijiro didn't even have the energy to float. He laid on the hard floor playing with his rubix cube. He wasn't sure how much more of this he could take.

"Father?" A feminine voice called from down the hallways "Father are you here? I was just about to call Natsuo-"

"FUYUMI!" Eijiro yelled, pressing up against the glass "fuyumi! It's me Eijiro! Eijiro Kirishima!"

"Eijiro?"  Fuyumi walked into the room and when she saw him her face turned white "w-what's going on?!"

She ran to him and put her hand on the glass.

"I don't have time to explain, but please, please get me out! I've been here for months. No offence but your dad is a huge asshole!"

"Fuyumi?" Enji's voice was down the hall. 

Eijiro cursed and then pointed to her phone "t-take a picture! At least show Katsuki I'm ok…"

"Eijiro…" Fuyumi looked so sad for him as she fumbled with her phone "I know my dad used to talk about mermaids all the time but I never thought…"

"Fuyumi!" 

She snapped a picture and whispered "I'll come back for you" before running out of the room.



"I'm gonna murder him" Katsuki was fuming as he stormed towards the Todoroki estate "it's been a whole /year/"

"Bakugou I know but we have to think through this"

Shoto put his hand on Katsuki's shoulder "we have to come up with a plan"

"The plan is to run him over with a truck" Katsuki hissed, shrugging Shoto off, taking two steps forwards and then crumbling to the ground "FUCK" 

"Bakugou, I told you those songs were bad for you" Shoto sighed and helped him back to his feet.

"Shut. Up." The blond groaned "this wasn't the songs it's just…" his stomach growled "I honestly can't remember the last time I've eaten." 

Shoto shook his head "Bakugou…"

His eyes lit up "take me to your house" 

"What? I live in an apartment now-"

"But you can take me to your house. That's where your bastard father has Eijiro" 

Shoto pinched the bridge of his nose "but we need a /plan/. You can't just break in fists flying, there are guards and alarms. I doubt my father will just hand him over"

"Your father abducted a man" 

"My father has lawyers that might be able to fight against that" Shoto spat "I hate his guts but I will admit that he has a silver tongue. Legally he can argue Eijiro isn't a person and he has permits to own large sea creatures. "

"This is bull shit" 

When Eijiro woke up the tank had been drained completely of water. 

"What the hell?" 

"Good you're awake" Enji said, he was clicking away at his laptop "I have a question for you"

Eijiro growled and sat up, resisting the urge to split his tail into legs. It would be smart to keep that a secret from Enji. 

"There's a lot of stories about mermaids but two things seems to be consistent" Enji began, rising from his desk and approaching the tank

"one: that you have magical voices that can enchant people and two: that your tears and/or scales have healing properties"

Eijiro frowned but said nothing.

"It's become clear that you refuse to lead me to your mate so I have to find another way to make you profitable. So I'm giving you a choice" he pressed his index finger against the glass as if he were jabbing it against Eijiro's chest

"either you willingly participate in experiments to figure out what magical abilities you possess or I will find a way to force you. Trust me I will make sure the latter is not pleasant."

"If you find out I do have something of value what are you going to do?" Eijiro asked, pulling his tail to his chest and hugging himself 

"Whatever I need to do to make my dreams a reality" he said simply "think about it. We start later today" 

Enji came back quicker than Eijiro would've liked with a duffle bag, video camera, and a small trembling woman with long white hair.

The woman didn't bat an eye when she saw Eijiro, in fact she didn't even seem to notice him at all, she just stared blankly at the wall. Enji offered her a seat, but she didn't respond so he set down his stuff and guided her to sit down.

"Have you made up your mind merman? Enji said without looking at him. 

"I have a name" Eijiro grumbled, eyeing the duffle bag the other man was unzipping.

 He couldn't see what was inside, but it was something metal… Enji raised an eyebrow and Eijiro swallowed thickly.

"What do you want me to do?"

"I want to test what your voice can do," he said, sticking ear plugs in his ears and turning on the camera.

Eijiro frowned and then looked at the woman "You want me to sing to her? Why?"

Enji didn't hear him, just motioned for him to hurry up. Eijiro gnawed at his cheek. He really wasn't sure what his singing would do, Katsuki said his singing was like being wrapped in a warm weighted blanket. But that was Katsuki. This woman didn't seem fully there…

"Hurry up!" Enji yelled, the sudden loud noise caused the woman to jump out of the chair, her eyes wide with fear.

She started screaming, collapsing to the floor with her hands up like she was about to be beaten. Eijiro dragged himself to the glass and put his hand against his trying to get her attention.

"Hey! It's ok!" He said looking at her and then at Enji  "what's wrong with her?"

Enji reached out to touch her but thought against it and glared at Eijiro "hurry up" he said just loud enough to be heard over the woman's screams.

Eijiro is freaked out, but he does his best to sing calmly. It takes a few seconds for the woman to stop screaming. He relaxes some when she does, glancing at Enji to gauge his reaction. Enji was staring at the woman intently, his scowl had diminished slightly.

The woman stood up and put her hands in the glass over Eijiro's. He smiled at her and sang a little louder, her grey eyes got a little brighter and some of the creases in her face softened.

Then suddenly her eyes rolled back, her fingernails extending into sharp claws that punctured the thick glass and cut into Eijiro's palms. The merman yelped and jumped back. 

"Rei, NO!" Enji yelled, wrapping his arm around her waist and pulling her away from the glass.

Rei's claws dug deep into Enji's arms and he dragged her out of the room, leaving Eijiro terrified and confused.