Note: This is a fantasy AU in which (y/n) is a siren, a mythical beast similar to that of a mermaid only a siren is carnivorous.

Quirk: none

Requested by: Golden_wind_edits

 I sat on the rocks in the small cove I came to regularly, kicking my tail back and forth in the water. I was a siren, a mammal that lived underwater who had the upper half of a human and the lower half of a fish. Sirens hadn't gotten the best of reputations. We were predators and a lot of time we fed on mainly fish, however there were times when we'd crave something we shouldn't: humans. We'd surface and use our alluring voices to attract the attention of anyone on a boat nearby, them automatically becoming hypnotised by our singing. The human would be put under a trance, desperate to find the source of the music and once they saw us they'd be attracted to us thanks to our beauty, however the poor human would end up being dinner mere seconds later.

I didn't enjoy taking part in such hunts, as the world of the humans had come to intrigue me so much that the idea of taking a life frightened me. Sirens had become magical creatures to fear due to the fact they had taken the lives of so many humans who dared to venture out to sea, which meant that slaying a siren offered a big reward. Because of this my parents didn't want me going anywhere near the surface, but I just couldn't help myself.

I regularly came to this cove, just wishing I could explore the land beyond it. Thankfully as this cove was surrounded by cliffs it was unlikely that I'd be seen and if I was then the water in front of me was deep enough to dive into. "Excuse me," a voice suddenly snapped me from my thoughts and I turned to see a human walking towards me. He had red and white hair, was wearing a blue tunic and had a sweet smile on his face. "I'm lost, I was wondering if you could give me directions?"

I just stared at him for a moment, appreciating his beauty before spotting his sheathed sword by his side. I let out a sudden shriek making him jump, then jumping quickly in the water to avoid the likeliness of being impaled. He did look kind however, so I couldn't help but poke my head out of the water before I swum out too far. I saw him stood on the beach, looking directly at me. For a moment we simply stared at each other with intrigue, and I was quite surprised that his hand went nowhere near his sword.

"Sorry, I didn't mean to frighten you!" He called out. "Are you sure you should be swimming that far out?"

I remained silent, him having obviously not noticed the fact I had a tail as opposed to a pair of legs. "I was just wondering if you knew the way back to the Todoroki Kingdom?" He asked and I shrugged. I lifted the end of my tail out the water and noticed his eyes widen. "You're a mermaid?" He asked. We were often confused with that species but we were different as they had gills and were a lot less bloodthirsty, whereas we were mammals who needed oxygen to breathe. I shook my head to answer his question. "You're... a siren?" He asked and I nodded. I expected him to gasp and run away but he didn't, he remained stood and I hadn't even used any form of hypnosis on him. "I've never met a siren before," he said and that didn't surprise me, as usually humans who met sirens would end up being dinner. I smiled at him, pleasantly surprised that he wasn't running away. "Well... thanks anyway."

I nodded again before quickly diving under the water, feeling my cheeks heat up a little. I swam down until I could see our underwater castle trying to come up with a lie I could tell my father as to where I had been.

"(y/n)!" My father who was also the king of the sirens called out to me as I approached the castle. I flinched a little, seeing him and his guards swimming up towards me. "Where have you been?"

"Er... just to the caves," I lied, there being a series of intriguing underwater caves nearby but he frowned.

"Don't lie to me, I sent your brothers there to look for you but they couldn't find you!" He shouted and I sighed, knowing I had to tell him the truth.

"Fine... I went to the coast," I admitted and he let out a dramatic gasp.

"How could the only princess of this colony go to the coastline?! You know we have to surface out at sea so that the humans don't see us!" He shouted, pulling me back down towards the castle.

"I know but the coast is so beautiful! I just have to see it, it's stunning, and the land beyond it looks amazing-,"

"No! You will never talk of this again, and I forbid you from going anywhere near the surface without supervision!" My father shouted and I sighed, nodding in defeat. My eldest brother Karma escorted me back to my room and when I was finally on my own I swam up to my window, looking out towards the surface and just wishing I could be up there. I thought about the human I had seen earlier and wondered whether he did find his way back to the Todoroki kingdom. I thought about how he didn't seem fazed when he realised I was a siren, and I thought about his sweet smile. He was charming and all throughout the evening I couldn't stop him from entering my thoughts.

- Timeskip -

The next day I looked out towards the surface, wanting to go back up to the cove to see if there was a chance the human had come back. "(y/n), it's time to Rise," Karma pulled me from my bedroom and took me to the throne room. 'Rise' was what we called our daily swim to the surface to breathe, our lungs able to hold twenty-four hours worth of oxygen.

With our guards around us we swam to the surface, far away from the coastline and the humans. From where we were we could still see the cliffs, but mere moments later I was being dragged back to our castle by Yuuma, another one of my brothers. "This is unfair," I scoffed, folding my arms as he took me back to my bedroom. "I feel like I'm being held in a prison!"

"Look, dad just wants to make sure he knows where you are. He wants to keep you safe, we all do, is that so bad?" Yuuma asked.

"I'm careful with what I do," I said sternly and Yuuma sighed.

"Do you need anything?" He asked and I shook my head. "Don't leave this castle (y/n)."

"Fine," I rolled my eyes dramatically as he left. I knew there were guards on my door so I instead went to the window, slipping out of it and making sure I wasn't seen by any of the other guards that patrolled the exterior of the castle. I swam as quickly as I could away from the castle and towards the coast, finally feeling free and hoping that I could see the charming human again.

Carefully I peeked above the surface, there thankfully being no-one in sight so I headed to the rock I usually sat upon, appreciating the view. A rustling behind me suddenly caught my attention, and I turned to see the charming human working his way down the steep path that ran along the side of the cliff. Still feeling cautious around humans I dived into the water but kept my head above the surface, watching him as he approached. "Hello again," he said politely. I noticed that this time he didn't have his sword with him, and I spotted his white horse on top of the cliffside.

"Hello," I said simply, staring at him.

"I wondered whether you'd be here again. It's a beautiful place," he said admiringly looking around the cove.

"I'm not supposed to be here," I admitted.

"Really? Why not?" He asked.

"Because humans hunt sirens," I said plainly and his mouth formed an 'o' shape.

"That explains why you were so jumpy yesterday," he said and I nodded. "Well, I don't have any weapons on me. Plus I'm not a murderer," he added and I tried to fight back a small chuckle. "Why do you come here if you're not supposed to be here?"

I remained quiet, not knowing if I could trust him or not. He had a trustworthy sense about him but I didn't want to fall into a trap so I stayed silent and in the water. He looked at me, apparently patiently waiting for an answer but I wasn't going to give him one. I kept my eyes directly on him, watching his every movement carefully just in case.

"I probably should introduce myself first before asking intrusive questions," he mumbled, rubbing the back of his head and I nodded. "I'm Shoto Todoroki, prince of the Todoroki empire."

"Shoto Todoroki," I repeated and he nodded. "Son of Enji Todoroki?"

"Er... yeah," he muttered and I swam further away from the cove.

"He has slaughtered many of my species," I said and Shoto Todoroki sighed.

"He's not the nicest of men, trust me I know," he said, gesturing the large burn mark that covered his left eye.

"He did that to you?" I asked and he nodded. I was analysing the prince in front of me, and I finally came to the conclusion that he was trustworthy, so I swam closer to the shore to the point where I could sit on the sand. "My name is (y/n) (l/n)."

"It's nice to officially meet you," he said politely. He came and sat on the sand near me, just out of the small waves reach. "So... why do you come here if you're not supposed to be here?" He asked his earlier question again and I sighed.

"Because I want to explore land. It looks so beautiful," I said, looking towards the top of the cliffs.

"You don't like living in the sea?"

"I don't hate it, it's just my family are very protective. Our kind have always been at war with the humans so they forbid me from coming up here but I can't help myself. I just wish I had legs," I said, brushing my hands against my tail.

"I think your tail is beautiful," Shoto Todoroki said.

"Excuse me?!" I shouted and he went as white as a sheet.

"S-sorry! Is that something I shouldn't say?" He asked desperately. I knew he didn't know any better so I let decided to let it go. "I didn't mean to insult you," he said quickly.

"It's okay, I know you meant it as a compliment," I smiled comfortingly at him. He let out a sigh of relief and I couldn't help but laugh. Together we began chatting about life as a human and life as a siren, comparing our day to day routines and struggles. I was feeling more and more comfortable in his presence, unable to believe that I'd get along with a human this well after just a second encounter with them.

When the sun began to set we realised just how long we had been talking. We knew we both ought to head back to our kingdoms, but it seemed as though neither of us wanted to leave so we organised to meet up the following day.

I swam back to the castle as quick as I could, and expected to get and earful from my father but I was surprised when I realised he hadn't even noticed I was gone. In fact, his attitude from yesterday had changed completely, and he suddenly seemed much more interested in me which was unusual given the fact I was often drowned out by my five brothers. Naturally I didn't tell him of my adventure that day, no was I going to tell him that I planned to go to the surface again tomorrow.

That night I found it difficult to sleep, having never had anyone enter my thoughts more than Shoto Todoroki.

- Timeskip -

It had been weeks and every day Shoto and I met up in the cove. When I wasn't around him I longed to see him, and he admitted to missing me when he was back at his palace. Shoto had mentioned that there was a possible way for me to be able to explore land and fulfil my dream, to which I nodded eagerly. He said he'd find out more for me but he hadn't mentioned it since.

Once again I slipped from my quarters in the castle and avoided the guards, heading in the direction of the cove. I swam as fast as I could towards the rays of sunlight and gasped in fresh oxygen when I reached the surface.

I wiped my wet hair from my face and looked over to the cove to see Shoto, however stood next to him was a woman in a hooded cape. I let out a loud yelp and dove under the covers, just after hearing Shoto call out my name. From underwater I could make out their silhouettes and saw Shoto actually entering the water, calling out to me.

Carefully I poked my head up from the surface and I saw a warming, relieved smile on his lips. "(y/n) it's okay, Uraraka is a friend," he assured, reaching out for my hand but I hesitated. "Trust me, (y/n)," Shoto whispered and I finally nodded, swimming back to the shore.

"Hello (y/n) (l/n)," the woman in the cape said and I froze in fear, hiding behind Shoto. "I believe you're searching for a way to explore land despite being a mammal of the ocean?"

"Y-yes," I stuttered, still clinging onto Shoto.

"I have found a way for you to do so. I have a potion here that will transform that tail of yours into a pair of human legs," she explained and my eyes lit up. "You will be able to walk and you will have human legs permanently."

"Permanently?" I repeated and she nodded. "But... what about my family?"

"I'm sorry, it's a permanent spell. There's no way for you to alternate between the two," Uraraka explained and I looked up at Shoto who had a sad expression on his face.

"C-could you give me some time to decide?" I asked.

"The potion will be available for twenty-four hours. After that it will be ineffective," she explained and I nodded. In the blink of an eye she had disappeared, leaving Shoto and I alone in the cove. There was silence between us before Shoto collapsed next to me, not caring about the fact he was now soaked.

"What should I do?" I whispered and he sighed, his head in his hands.

"You can't leave your family," he said after a moment and my heart broke, wanting to live a life above water, hopefully with him. "Can I be selfish for a moment?" He suddenly said, looking directly at me. I nodded and to my surprise he cupped my cheek and pulled me in for a kiss. I happily reciprocated, having never felt warmth like this before. It felt incredibly, and sparks of emotion flew around in my stomach.

"S-Shoto," I mumbled, looking into his heterochromatic eyes as we pulled apart.

"I love you," he admitted and it felt as though my heart exploded.

"I think... I think I feel the same way," I whispered and a small smile played at the corner of his lips. "I want to live a life with you up here, I want to be with you and I want you to teach me things."

"What about your family?" He asked and I felt a tug in my heart.

"They wouldn't understand," I muttered. "They hate humans, and they lock me up whenever they find out I've swum too close to the shore." Shoto wrapped his arm around me and pulled me into his warm body. It was this action, the feel of being in his arms that helped me make up my mind there and then. "I'm going to do it. I don't care, I want to do it, I want to live up here with you."

"Really?" He asked desperately and I nodded quickly.

"I need to tell my parents though, but I'll meet you here again in the morning?" I asked, the sun now setting.

"Absolutely," he whispered and we shared another passionate kiss before I headed underwater, waving at him. I was in an incredible mood, feeling nothing but happiness as I swam to the castle, through the gates and towards the throne room. Confidence and desperation was fuelling me, as well as excitement at the thought of being able to see land.

"Mother! Father!" I called out as I entered the throne room.

"Ah, (y/n), what're you doing here? I thought you were in your chambers," mother said but I shook my head.

"I have some very big news. I've fallen in love," I said and they gasped.

"What? With who?" Father demanded and I sighed.

"With a human I met in the cove," I said and launder gasps were heard from everyone in the throne room, including my five brothers.

"A HUMAN?! YOU'VE BEEN CONVERSING WITH A HUMAN?!" Father roared making me back away a bit in shock.

"I have!" I shouted, trying to keep some of the confidence I had before I entered the room. "I've fallen in love with Shoto Todoroki, and he loves me! I'm going to live on land and you can't stop me!"

"Oh yes I can! No daughter of mine, no princess of the sea shall dare live on land! How do you even expect to live up there?!"

"I'm going to get human legs," I said firmly and my mother looked as though she might feint. Father immediately swam up to me and grabbed my wrists tightly, his strength preventing me from pulling away.

"H-hey! Let go!" I cried out, trying to pull myself free but it was impossible.

"You will never leave this castle ever again! You'll be locked up and I refuse to let you leave!" He shouted, pulling me down a chute towards the dungeons.

"Dad! Don't you want what's best for me?!" I asked desperately.

"This is what's best for you!" He shouted, pushing me into a small dungeon and slamming the door in my face. I immediately swam to the door and attempted to open it but he'd locked it, and I saw him swim back up the chute through the small window on the door.

I spent ages pulling at the door, trying desperately to open it but there was no way of opening it. I began to panic, wondering if I really was trapped down here and wondering if I would ever get to see Shoto again, let alone be back in the cove in time to drink the potion. I tried desperately to call out to my parents or my brothers, hoping anyone would understand but I was getting nowhere. Tears were leaking from my eyes as I let fear overtake me, wondering why I didn't drink that potion as soon as Uraraka gave it to me. If I had I'd be up on the beach with Shoto now, him teaching me how to walk. The thought of that brought a smile to my lips, but the tears continued to fall as that dream was slowly slipping through my fingers like sand.

I wasn't sure how long I'd been in the dungeon but I was beginning to get scared about the twenty-four hour effectiveness of the potion. I didn't know how long prior to Uraraka showing it to me it had been made, so I knew I needed to get to the surface as soon as I could.

In a desperate attempt I tried pulling at the bars to the window as opposed to the door, hoping I could shimmy one loose. A loud clang echoed as I grasped a loose bar, pulling at it harshly with all my strength. "(y/n)?" A voice caught my attention, so I let go of the bar and tried to act natural.

Yuuma swam up to the small barred window in the door with a solemn look on his face. "Y-Yuuma, what're you doing here?" I asked and he sighed.

"I can't believe dad put you in here," he admitted. "Do you... do you really trust this human?"

"With my life," I assured my brother.

"And do you really love him?"

"With all my heart."

I heard a clang and realised Yuuma was unlocking the door. When he opened it I swam into his arms, hugging him tightly. "You deserve to live a happy life, and if being with the human makes you happy then that's what you need to do. I have to admit, I'm not thrilled at the thought of you being turned from a siren but I'm your brother so I'll support you completely."

"Thank you Yuuma," I whispered, holding him tightly.

"I'll get to see you won't I?" He asked and I smiled, nodding.

"I'll be sure to visit the cove often. You can see me there," I said and he smiled.

"C'mon, I'll take you there," he whispered, us swimming up the chute. Yuuma had already packed a few of my things for me, and together we swam out of the castle. According to Yuuma it was now early morning, and when I told him of the potions time limit we swum even faster.

Thankfully we arrived at the cove just as the sun was rising, but to my surprise Shoto and Uraraka were already there. Shoto had been pacing back and forth, but called out to me as soon as he saw me surface. We approached each other as quickly as we could, holding onto each other. He began dragging me ashore, closer to Uraraka who stood there with the potion in hand.

"Who's this?" Shoto asked pointing to Yuuma who was watching me protectively.

"My brother, Yuuma," I said and Shoto gulped as Yuuma stared at him with a frown on his face.

"So, you've decided to take the potion?" Uraraka asked and I nodded. Shoto held me in his arms as I consumed it, and as soon as I swallowed there was a bright white light around my tail. It was almost blinding, causing all of us to look away, however I looked back when I felt something weird. To my relief I saw human legs were my tail once was, and couldn't help but laugh in thankfulness.

"They feel so strange!" I said before I could stop myself. "Thank you, Uraraka," I added and she smiled.

"No problem," she said before clicking her fingers and vanishing. Shoto helped me stand for the very first time but my legs were weak and I collapsed almost immediately. He held onto me tightly though and helped me move them back and forth, us making our way to Yuuma.

"I can't believe this is happening," he mumbled, his lip quivering.

"Thank you Yuuma, for everything," I whispered, pulling myself towards him and wrapping my arms around him. We had an emotional cry but I assured him that I would be able to see him here at the cove, to which he nodded. He discreetly threatened Shoto about keeping me safe before handing me my bag of wet belongings, then departing to the depth of the ocean.

"I'm so glad we can finally be together," Shoto whispered, helping me to stand again.

"Me too. This is going to be our adventure," I said, pulling him in for a kiss as he held me tightly.