#mer! reader

Courting a human sucks. It is all sugar-coated, a bunch of nonsense to try to appease the other. The way mers did it was simple. Show potential mates you can provide with gifts and food, and make sure your bodies are compatible. Of course, Bakugou hasn’t gotten that far with you and his face heats up whenever he thinks about it. But in the less dirty sense, he knows you find his body attractive and your body was equally as perfect.

So yes, the king should be done with the whole courting thing. It’s been about a month now and you are still frustratingly human. You haven’t given in to his antics.

You haven’t accepted the blonde because frankly, you are absolutely terrified of being a mermaid. Sure, you didn’t have much family nor friends to leave behind, but still, it was a whole new world. You weren’t sure if you were mentally prepared for that.

“You. Pretty,” The mer at your feet huffs, frown still on his face, contrasting the compliment. From his research, he decided that humans like compliments.

“Yeah? Thanks, Kats, but you have told me that ten times today.” He trills in annoyance and uses the tip of his tail to splash water at you. You squeal but giggle at the cool water that falls upon your face.

He grips your left leg and presses his face to your calf. “Mate now?” He asks, just as he had done for the past couple of days. He then begins to gently nibble on any skin he can lay his teeth on. You give him a sharp glance, warning him to be gentle. Your legs are already littered with bite marks thanks to a certain someone. He rolls his eyes, but abides, not wanting to piss you off.

Once satisfied with the mer you sigh. “Yknow, human courting is more than just giving compliments.”

He lets out an overdramatic growl and you raise your eyebrows. His orange face fins fall flat against his head. “Human ways stupid,” He hisses and you roll your eyes.

“Forgive me King Bakugou, ruler of the sea, for being a human,” You tease sarcastically and he glares at you. You smile and reach to pet his hair, he grumbles but leans into the touch. “Alright, I have seen that you tried. I'll be your mate Katsuki. Just give me a week to you know–prepare to be a mermaid?”

He pulls away from your leg, eyes wide. He almost seems to be happy, but of course, knowing Katsuki, he wasn’t about to show it. So, instead, he barks a complaint, “Too long. Now!”

You gently push the tip of your foot onto his forehead, forcing his head to tilt back. He bares his teeth at you, but doesn’t move from the position. “A week. Keep complaining and I won’t be going at all,” You threaten and he narrows his eyes at you.

Sometimes, Katsuki was demanding. It was fine in most cases, but if you sit there and take it all the time, it will definitely go to his head. You are not one of his subjects to boss around. 

So, alas, he moves away from you and nods with a huff.

He swims back up to the dock and uses his tail to push himself out of the water, as he has done countless times. He rests his forearms next to your legs, successfully holding you still. He is slightly shorter than you in the position, but still way more threatening out of the two of you. 

“Kiss?” He asks, but it comes out more like a demand.

Nevertheless, you are happy to oblige, and you swear you could see a small smile on his face when he presses his lips to yours.

When Katsuki heads home for the day the last thing he wanted to see was two idiots in his court. 

“Did you see when she pressed that strange thing on his forehead?” The blonde-haired, and yellow-tailed, mer trills. He stares curiously at the figure above the water that is walking away.

“Yeah, and Bakugou didn’t even try to bite it off! He is totally whipped.” The red-headed shark, who looks almost exactly like a mer, excluding the extra large fin on his back, says in return. The two are so close to one another that they look like two schoolgirls talking about their crushes. They don’t seem to notice their king’s presence.

Katsuki, suddenly grabs the two of them by the back of their necks, causing them to jump. He has a murderous smile when talking. “And what the fuck are you two idiots doing over here?”

The two eye each other and smile sheepishly. “Just you know. Looking for our king!” Eijiro, the braver out of the two says enthusiastically.

“And new queen,” Denki half mumbles and Katsuki eyes him suspiciously. He can’t help but like the way it falls from one’s mouth though. But, the larger mer refuses to say that out loud, so instead he growls and drags the two away.

Then, he begins planning for your arrival.

Today was the last day of you being human. You sigh and go through your items, wondering if you’ll ever need them again. Becoming a mermaid is a life change, obviously. So, you were struggling just a little. 

You got rid of most of your stuff, but you were hesitant about removing them all. If going with Katsuki didn’t work out, would you be able to come back? You had to ask later.

So here you are, walking out of the small shack you called home. You approach the dock with only a bag full of the mer’s gifts during his courting process. You couldn’t imagine leaving them behind.

Katsuki is at his usual spot, peaking his head above the water. A pink figure is next to him. Your eyes widen, in the six weeks you knew the mer, he has never introduced you to anyone. This had to be the person changing you.

You gulp, but a familiar bark calls you over. You smile nervously. “Hey, Kats. Who’s this?” You take in her appearance. Bright pink hair, skin, and tentacles. An octopus. You have never seen one that looks like her. She was beautiful.

“Mina. Friend. Ch-Change you.” The octopus tried to talk but it comes out as strange gasping and gurgles. You could tell it was the mer language but was definitely a little different considering it was coming from an octopus. So you just smile and wave at her.

She smiles so wide in return and you begin to feel a little comforted. Mina grabs at your ankles and begins to continue talking in the language you cannot for the life of you understand. You look toward Katsuki for help, a little afraid that she might drag you in. She looks nice enough, but she is a sea creature. You don’t trust them completely yet.

“Look at her tentacles Bakugou! Only two of them. How weird!” Katsuki rips her hand away from your body and growls at her.

“Watch it. That is your Queen that you dare to touch without my approval.” Mina shrinks her hand away and nods hesitantly. She totally forgot how important you are. 

The octopus tries to do a curtsey, but it looks more like she just submerged more of her body in the water. Katsuki huffs and nods while you look at her confused. “Katsuki what is she doing?”

“Showing Re-spect. Queen.” You look at him wide-eyed. You were not going to get used to this. 

“Oh. Um, thank you?” Mina has no idea what you are saying but continues to stare at you with stars in her eye. Unknown to you, but she has been waiting for the day the blonde finally chose his mate for years now. You laugh awkwardly.

She grins at the sound and turns toward the king who is wishing this process went a lot quicker. “What did she say? Tell me Bakugou!” 

He rolls his eyes. “She says thanks. Now can you get on with it?” She nods, used to the blonde’s behavior, and beckons Katsuki to grab for your hand. He holds his hand out to you, and you take it. He begins to lead your hand to the octopus but stops.

You begin to tremble, nerves getting the best of you. Katsuki looks at you, eyes furrowed with concern. He quickly scans the area. “No danger. Don’t be afraid. Protect you. Promise, mate.”

You smile at the reassurance but it doesn’t help. It wasn’t like you didn’t want to be a mermaid, but this once again is a huge change. Your whole world is about to do a 180. 

You don’t know how to phrase this any nicer, but you have to get it off your chest. “If I…If I want to go back home, as a human. Will I be able to?” 

Katsuki grimaces. He had to admit that question hurt, but it was reasonable. Mers may mate for life, but humans don’t. After a while would you leave? Would he let you leave him? He didn’t like pondering such nonsense things. 

But, for your sake, he turned to Mina and translated your question. She takes a second to think about it but nods and explains how easy it is to reverse the spell. 

He feels hesitant about telling you this. “Yes. But–Don’t leave. Stay. With me.” Katsuki pauses, looking up at you. He huffs. “Please?” He has never asked for anything in his life, and if anyone in his court heard this they would be flabbergasted.

This is also the first time he has also said please to you. You smile and run your fingers over his webbed ones, and nod at him reassuringly. “Wasnt planning to. Just wanna keep my options open. Just in case, yknow, something bad goes wrong.”

He, like usual, grumbles, but he does understand. You’re smart. Thinking about how a situation could go bad, and how to keep yourself safe. Things queens should be thinking about it. So, although it feels wrong instinctually to agree with you, he can’t help but feel a little prideful at your statement. “I un–understand. But, nothing go wrong.”

You chuckle at his statement, but don’t disagree. You hope nothing does go wrong. You hope that the two of you will stay together forever while you are down there. 

Mina gurgles, annoyed that she can’t understand what you guys are talking about. Katsuki clicks at her sharply and she rolls her eyes. Then the mer brings your hand onto hers. You gulp. “Ready?” He barks.

“As I’ll ever be.” 

Your vision begins to fade, and the last thing you see is Katsuki grinning, canines hanging out of his mouth that looks almost animalistic.

When you awake you are underwater and breathing it. You of course panic when your first wake up, but immediately remember.

You begin to take in your surroundings. You are in a dark sort of cave. It’s hard to see much, but you are very much alone. It unnerves you. Where the hell was Katsuki?

You begin to move but forget about your new appendages. You quickly turn around to get a look at your tail and gasp. It was pretty. A light green, with glittering scales that are not that exciting in the darkness. But still, you could tell it was beautiful. It was definitely smaller than Katsuki’s massive orange one, but definitely still large. 

You put all your years of playing mermaid in the public pool into the effort at this exact moment and suddenly, you are swimming. Not fast, of course, considering you are definitely confined into a small space, but definitely something. You smile wide and swim in circles, twirling around, fulfilling your childhood dreams.

Suddenly a noise startles you out of your thoughts. You freeze and quickly duck low, hiding from whoever it was. Chances were, it was Katsuki, but you aren’t willing to risk it. 

“I don’t know man, this seems like a bad idea. Bakugou is going to kill us if he sees us.”

“Just one peek. It will be fine, Kirishima, stop being such a guppy. We will ask her not to tell him we were here!” Eijiro looks over toward the blonde mer, and nods hesitantly. He begins to drag the shark toward the end of the cave.

Suddenly, a rock is thrown at them. Not hard, considering you are not used to the dynamics of force in the water, but definitely still there. The shark jumps and looks at you in shock. “M-My Queen.” The two strangers bow at you and you grab another rock.

“Who are you guys? And where is Katsuki?” You hiss, green face fins spread in alarm. The two look at you in shock.

The yellow-tailed mer is the first to respond. “How…How can you understand us? Didn’t you just transform?” 

You begin to lower the rock in confusion. Then it hits you. You weren’t using your vocal cords the same as usually do. You were clicking and trilling at them. It was instinctual, you didn’t even know you were doing it. 

Another figure appears and you hiss on instinct. When you do so though, you immediately cover your mouth, eyes wide in shock. 

“I did it!” Mina says with a smile and swimming up close to you, way closer than normal personal space. She grabs your hand and begins to assess it. “I gave you something that helps with understanding mer linguistics. I just couldn’t wait to talk to our new Queen!”

“Does the king know?” Eijiro says eyebrows pinched in concern. He knows that Katsuki doesn’t like doing things without his approval. Especially stuff involving his new mate. That’s why if he and Denki were found out, they were fucked.

“Well, no! But he will be happy! Anyways, what are you guys doing in here? I am making sure the transformation went well.” She turns back to you and runs her hands over your face fins. You flinch at the strange feeling. “My Queen, can you please open your mouth for me?” You abide, and she begins to count your teeth and checks your canines.

Kaminari swims closer to the octopus. “We wanted to take a look! Bakugou really scored, huh? She is so pretty and–”

“I’ll ask you guys again. Where is Katsuki?” You hiss, cutting the blonde mer off. You weren’t trying to be rude, but you were overwhelmed, and the fact that he is not here when you are so vulnerable is upsetting you. 

“Demanding! Perfect for a ruler!” He responds, a smile on his plastered on his face like he was used to being treated like this.  

“He is hunting for you, my Queen.” The large shark, you were most wary about says, with a soft reassuring smile on his face.

“Y/N. Please, all of you call me Y/N, all this “my Queen” talk is throwing me off.”

They all look at each other hesitantly, wondering how exactly Bakugou will feel about being on a first-name basis with you. But, you were their queen, and this was your first command. So they all nod at you. “Of course…Y/N,” The blonde mer says and you smile. “Im Denki and this is Eijiro. And of course, you met Mina. We are part of King Bakugou’s court.”

Mina lifts your arms up and moves them around, humming to herself. “Anyways, don’t worry, he will be back soon. These two idiots aren’t supposed to be in here but don’t be afraid they are harmless.” The two grin at you at her statement and you return the gesture.

Suddenly, there is noise at the entrance of the cave. Mina drops your arm instantly, and moves to take a peek. She gasps and quickly turns her shocked gaze toward the other two. You watch the boys’ faces pale drastically. 

Eijiro quickly stutters out, “M-My King….You are here–” before the two of them are pinned to the floor, held down by the backs of their neck. You gasp and Mina sighs, knowing this was going to happen.

“What the fuck are you two doing in here? I should banish you. Coming in here on my sleeping mate, your Queen, without my permission,” He hisses out, face fins spread wide, pupils constricted, and claws digging into their necks, causing the two to wince. “No, not banish, I should kill you guys for–” 

You let out a small yelp, shocked by what the hell is happening. You have never seen Katsuki angry before, and now he is using full sentences to threaten to kill people. His very own subjects! It made you think about what he could do to you.

That’s not even talking about his appearance. He looked animalistic. Like he really would see his threat through. You didn’t know if you really were cut out for the world under the sea. 

Katsuki whips his head toward you at the sound, and his eyes widen. He takes in your very much shaken appearance, trying to hide behind Mina. He of course didn’t mean to scare you. He assumed you were still asleep. “Out. All of you. I’ll deal with you later. Now!” The three quickly scamper out of the cave, leaving you alone with the king.

He sighs and rubs at his face. He swims up to you, but instictually, you flinch away due to his appearance. His eyes slowly contract back to usual and his facial fins relax. “Sorry. Sorry. Don’t be scared. Will not hurt you. Sorry. Mate. Protect.” He using your language again. It’s a little muffled under the water, but understandable. 

But what really shocks you was how desperate he sounds. He really was afraid that you were scared of him. It made your heart throb. You have to think about it, but you speak in your tongue. “It’s okay. I’m okay. You shocked me a bit, but I’m not afraid of you Katsuki.”

He gently grabs onto your arms and this time you don’t flinch away. He sighs and hugs you. Katsuki mumbles, “Those fucking bastards.” In your neck and you laugh. 

“I like them. Eijiro freaked me out at first, but they seem nice.” He jumps and pulls away from you, holding you not at arms length.

He furrows his eyebrows at you, confusion written all over his face. “What? Speak.”

“Um okay?” 

“What the fuck? How the hell can you understand–Mina. That idiot! I knew she would somehow ruin this.”  He pinches the bridge of his nose and you laugh.

“What’s the big deal? This is a good thing. You now can use full complex sentences. It’s honestly kinda weird, but now I can understand you more, without the growls and grumbles,” You reason and he looks away from you, a small blush on his face. He mumbles something under his breath. You hum in question.

“Nothing. I just–Whatever doesn’t matter.” 

You cock your head to the side. “C’mon tell me, if I am to be your mate I have to understand what’s going on in that hard head of yours.” He rolls his eyes at your grin.

Katsuki mumbles out, “Didn’t want you to learn it yet.”

You furrow your eyebrows in confusion and then bring back the teasing. “Why? So you could be the only one to talk to me?” You smile and lightly tug on the two orange fins attached to his face.

He blushes and turns away from you. You have your answer. A laugh falls from your lips and he growls in embarrassment. “You possessive little shit! How would I be able to rule a kingdom without speaking your language?”

“I would teach you the basics. You could ask me to translate the rest.”

“With your fantastic English speaking?”

“Fuck you! I’m fantastic at speaking it, better than you.” You laugh at his cocky statement, and his eyes fall to your tail.

His grumbles stop as he stares at your tail. He runs his claws over it gently, admiring it. You stop your laughter to follow his gaze. “It’s pretty. Smaller than mine. It fits you. I knew you were destined to be a mer.” 

You smile at him. It was rare for Katsuki to speak so gently with you, so you were soaking it all in. But, you turn the conversation back to what’s important. “You scared me earlier.” He scowls, remembering your terrified face, just a couple of minutes ago. “When you weren’t by my side when I woke up.” 

His ruby eyes scan your face. “I was hunting. I was with you every second for the past week. If I didn’t I would most likely starve to death. I don’t know why the hell you woke up the one time I was gone. It’s your fault.” You give him a glance that said, really? at his ridiculous answer and he scoffs, giving in immediately. “Sorry. Didn’t mean to scare you.”

“It’s alright.”

He nods before he leads you over to the stone ledge covered in seaweed that you awoke on. “Rest. You just shifted. Mina says you should be sleeping. Can’t have you die on the first day of being a mer.”

“Die?!” You screech and Katsuki laughs mischievously.  

“Im fucking with you. I didn’t dedicate six weeks courting your ass just for you to die. Sleep. Now.” You use your new appendage to hit his stomach at his teasing. But, you’re not used to your new strength, so you accidentally hit him way harder than you meant to. He winces and falls forward, having the wind knocked out of him. Your eyes widen and you spit out apologies immediately.

“Pretty and strong. Perfect.” He wheezes and you laugh nervously, fretting over him. He just pushes you back down on the slab, mumbling how he alright. He then curls up next to you and begins to lull you to sleep.

Two weeks go by, and now, officially you are Katsuki’s mate. Two nights ago it became official, and the both of you have bite marks on each other’s necks. 

The one on yours is huge, he didn’t even try to make it hidden. It’s right below your ear, and no matter how hard you try, it will be shown to everyone. Possessive bastard.

Katsukis is a lot smaller, you were hesitant about biting him in the first place, so you placed it near his collarbone. He stopped wearing jewelry so that it could be shown and you swear he goes out of his way to crane his neck to display it when talking to someone. It was ridiculous.

But, other than his antics being queen honestly hasn’t been that hard. His court loves you already and his mother absolutely adores you. She saw you once scold Katsuki for being mean to one of his subjects and fell in love immediately. 

You live in a palace. It was absolutely massive and was made out of gold. Katsuki says it has been here for hundreds of years. It was completely different than your beach shack, but you were growing fond of it.

Katsuki’s room is definitely very…Katsuki. It was more like a cave in all honestly. He says he likes to go with his roots. His instincts. Mers originally lived in caves after all. You have done some touch-ups to make it more home-like, but kept it the way he likes. 

The gifts the both of you received hang upon the walls. It was a little strange to see a tennis ball held in such a protective case, but you didn’t say anything, not wanting to hurt his feelings.

Currently, you were talking to Eijiro as you were swimming to the dining room. You have slowly convinced Katsuki to actually eat in the dining room with the rest of his court, instead of bringing dead fish back in his mouth like a wild animal. 

He agreed but forces the chefs to make his and your meals the fish he hunted. Everybody snickers about it behind his back, but nobody has the guts to say anything to his face.

Surprisingly, you actually enjoy eating fish. It took a couple of days of getting used to it, but it was a lot better when the chefs prepared it. You had no idea how they made the sauces for it, considering you guys were under the sea, but you knew you probably didn’t want to find out.

“And then we helped the guppy find his parents!” Eijiro clicks, snapping you out of your daydream. He was telling you about his day guarding the city.

You smile at him. “How sweet. I’m not surprised, you are a great soldier.” He grins at you and nods. The shark seems to have taken a liking to you, considering you don’t shit on him constantly like Katsuki does. You don’t mind. It was nice to have friends, you didn’t have many on the surface.

Suddenly the door behind you opens and the two of you turn toward it. Eijiro, like always, bows low in greeting. You smile.

Katsuki swims over toward the two of you, with the usual scowl plastered on his face. “Why talk to him?” He grumbles, not liking that you are alone with the shark. He knows nothing will ever happen, but still, it was annoying that he has so many kingly duties that he doesn’t get to spend as much time with you as his court does.

You rephrase his statement. “He asked us what we are talking about.” The shark nods and Katsuki looks at you like you slapped him. You cock your head, confused.

“Don’t trans–late. He is idiot.”

“You know he is a member of your court.”

“Our court.”

“Yes, our court.” He nods in triumph and you sigh, but smile. Katsuki has been going out of his way to talk to you in English. He likes the idea that only the two of you can communicate with one another like this. 

The blonde swims up to you and presses his lips to yours, without a warning. Eijiro lets out a disgusted noise, before turning away and heading to the dining room by himself. 

“Really?” You sigh when you pull away. He grins mischievously and grabs you by the hand, before leading you to the dining room.

Upon your entrance, your court “stands” from their chairs. They all bow and simultaneously say, “Greetings to His and Her Majesty.”

You smile and wave at your new family, you manage to get a small wave back from Denki. You still aren’t used to the whole dramatic greetings. Katsuki just nods in approval. 

Katsuki sits at one end of the table, and you sit at the other. You actually hate doing this, you much rather sit next to one another, but it was important for the king and queen to also show respect. 

You receive your custom-made meals, and your mate grins from across the room. “Salmon. Good.”

“Thanks, Kats.” You smile warmly at him, knowing he takes immense pride whenever he has “provided” for you successfully. He huffs but uses his hand to wave the thanks off. Denki has to hold back a laugh.

The others receive their meals and begin to indulge themselves. You are the only one who uses silverware, but you don’t mind, you are now used to the way merfolk eat. The first day it almost gave you a heart attack watching them viciously tear into the fish.

You talk to Mitsuki for most of the meal and occasionally join in Mina’s conversations. Katsuki talks to Eijiro most of the meal, but the two of you make eye contact multiple times. You always smile at him. It was a nice dinner. It always was.

You really love it here. Everyone is so kind to you. Being a queen is not too hard, but that is simply because Katsuki is really good at being a king. He is respected by everyone, so naturally, as his mate, you are too. Plus you haven’t had to make any life-changing decisions. Katsuki did that for you, and you were grateful. You didn’t have much experience ruling people.

Dinner ends uneventfully and you dont mind. The routine is nice. Katsuki leads you back to his room. It was the first time you have seen him all day besides dinner.

The day ends with just the two of you. You lay facing one another, and Katsuki runs his fingers through your hair. He kisses the bitemark on your neck. He then murmurs, “My Queen.” into your neck.

“Hmm?”

“Just like saying it.” You laugh lightly.

You sigh and look toward the stone ceiling. “It’s weird. If someone told me that I would be a ruler a year ago I would have fainted.”

He grins, canines on full display. You remember when they used to freak you out. Now you can’t help but love them. “Would you believe that you are mated to the strongest being of the sea?”

“I think you mean the most arrogant bastard of the sea.”

“Don’t act like you don’t love it.”

You roll your eyes and switch back to your native language. “Mated to a man who thought courting meant trading. What a strange thing.”

“Your fault! Dumbass!”

You grin at him. “How was that my fault? You really thought I was coming onto you that fast?”

He grumbles to himself. “Wouldnt be sup–rised. Happened before.”

You fake gasp. “Don’t tell me. Have you been trading with other mers before you met me? I’m wounded Katsuki!” You knew the answer to that, having heard him multiple times tell you that he only had eyes for you. 

“Yeah. Traded with many mers. Way prettier than you.” He nibbles on your jaw, a sign of affectionate teasing. He has also told you multiple times in high dramatics that he was “mated to the prettiest being of the sea.”.

You laugh and continue the joke. “Don’t worry, I understand. I “traded” with tons of other human men too.”

He growls and runs his teeth over the mating mark. “Joke over.”

You pet his head, still grinning. “Who said I was joking?” He looks up at you, squinting at you and frowning. He can tell by the look on your face that you are lying.

He quickly switches tactics to lightly gnawing on your skin, earning squeals from the ticklish feeling. He pins you down to stop your squirming. It doesn’t stop your hysterical laughing. “Stop! That tickles! Mercy! Katsuki!”

“Say it.”

“Say what!?”

He stares at you. “Fine! Fine! I have only traded with you!”

“And?” The mer prompts, as he moves to your stomach to lightly bite it. You continue to squirm, but you know what he wants you to say.

“And….Katsuki! Im going to pee myself! And I am so happy to be mated to the strongest being of the sea!”

“And?”

“And what?!”

“You know.”

“And I love being Queen of the sea! And I’ll never turn back human!” He releases you with a grunt and you begin to pant, trying to regain your composure.

He didn’t mean to get you to say that last part, but he can’t help but feel an immense amount of joy from the words. He is afraid you’ll get sick of the life of a queen. The reassurance helps.

Once you calm down, you glare at him for torturing you. “I am going to kill you Katsuki Bakugou!”

“With those little fangs? You can try.” You pounce on him immediately and the two of you twirl in the bed. He laughs and growls playfully at you. Katsuki barely lets you win. He smiles when he feels those dull claws, compared to his, pins him against the bed. He will let you have this moment, especially after what you just said.

The poor servants were left red in the face when they passed your door, hearing the thumping, growling, and squealing coming from the King and Queens bedroom.