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Izuku was still a small boy when his father introduced him to the world of humans, they all walked the same earth after all.


Their castle in the giant forest of mysteries, humans dared not traverse into it. In fear of the creatures that lived there, in fear of the demon king whose castle was taller than any man-made structure. The forest dead center of the human's world, no human knew exactly how large the forest was, how long demons had lived there. Not a single human knew that the demon king and prince were as gentle as could be.


Hisashi helped his son with a spell, to hide his little green demonic marks and to hide his twisty childish horns, to turn his claws into chubby little hands. Izuku looked like any human boy, save for his excited tail, how heavy it swayed side to side. Izuku was too young to learn to hide that much yet, but a cloak would do the trick. Hisashi held Izuku’s hand as the demon king opened a portal, a little bit away from a human village. Hisashi wanted to show his son the wonders of the humans, how they thought and how they celebrated with festivals and food.


“What food do they eat? Goblins? Sun ogres? No, they probably eat selkies, the ocean is close by!” Izuku looked around excitedly, taking in the sight of the oncoming village. Hisashi’s little spell broken quickly and the boy's marks appeared on his temples and his cheekbones. Izuku’s father sighed and placed another spell, a little more magical power behind it so that it would hold longer.


“I think mostly  they eat fish or chicken, Izuku.” Hisashi chuckled as his son pouted, he knew that answer was boring to his curious child. “Do you remember those large creatures; cows?”


“They’re not that large! I could pick one up, remember?”


“Yes, Yes, I remember. Though, humans can’t pick them up.” Hisashi stepped to the side, a horse-pulled wagon passing by them with leisure, Izuku’s eyes widen as he watched his first human sit lazily on the seat of the wagon. “They drink the milk of the cows, then humans eat the cows, cook their meat and such.”


Izuku made a face as he looked from the human to his father, the cows were so pretty when one wandered into the forest. At least the meat demons ate came from brainless demons, livestock that reproduced with the purpose to be eaten. Izuku still remembered petting the cow, staring into her beautiful black eyes and blinking when she blinked at him, her long lashes tickling his face when he got insanely close to her long face. She was beautiful, large and brown. He remembered how his mother demanded he put the cow down when he picked her up and ran to the castle with her.


Izuku found himself asking. “Does it hurt them?”


“If the butcher isn’t careful, yes, it hurts them.”


“Then, why do they do it? I thought humans were nice, father…”


Hisashi pursed his lips and thought for a long moment. “Humans are like us, they can be gentle, they can be cruel, that’s why you mustn’t judge one on the actions of another.”


“But if all humans eat meat then-“ Izuku’s round eyes found themselves attached to the town, how ribbons flowed off the roofs of houses, beautiful omegas and betas in dresses and gowns. Alphas in their best clothing. Izuku tugged on his father’s hand and bounced in place happily, he wanted to get closer and witness more of the human's village. His moments of cynical speculation forgotten quickly.


Hisashi followed Izuku where the boy led, young women placing necklaces of flowers around their necks, a red crown of flowers for Izuku. The boy smiled at them and sook they found food. Izuku following his nose until they reached a station, grilled duck strips for sale, just a piece of copper for two servings. Hisashi paying a piece of copper for a delicious treat for his son, Izuku’s fangs digging into the duck. Hisashi doing the same, matching his son's wide grin. His son's cheeks pink and he was glowing in the sun that light up the festival.


Izuku was literally glowing.


“That boy!” The merchant exclaimed, gaining attention from other humans who were close by, all of them looking in Izuku’s direction.


Hisashi pulled Izuku’s hood over his head, hiding his son’s glowing marks and sparkling green eyes. The child was growing stronger by the day, Hisashi’s spells weren’t working like they used to. Evidence of how Izuku would become the demon king, the child’s magical power already on par with his father’s. Hisashi picked Izuku up, the boy protesting as the sudden moves made him drop his food. Hisashi hastily walking away but he could hear the beginnings of angry murmurs, of scared crowds, of the demon child. The crowd turning from festivities to anger at the demons who entered their tradition.


“Izuku, do you remember how I said some humans are cruel?” Izuku nodded in confusion, he hugged his father’s neck, holding on tightly as he was jostled. “You can not show the humans how you look, they fear the unknown, fear those who look different.”


Hisashi hugged Izuku tighter as the boy's eyes watered, the poor child confused but his father's words scared him. The demon king made sure to start teaching Izuku everything of the human world when they returned to the castle, he didn’t want Izuku to be like his father. The previous demon king feared the humans, never left the castle, harbored Hisashi until the day the old demon died. Hisashi didn’t want Izuku to fear anyone or anything, he wanted him to remain curious until the end of his life.


Izuku began to cry for his mother, he had enough of the human world for his first day amongst them. Hisashi carried his son out of the village, Izuku’s tail curled under him in his lap. Once out of sight of the humans, he opened a portal, stepping through it and he stood in the forest of mysteries, close to the castle, a small walk to ward off any fear Izuku held onto, to air out the stressed scent Hisashi carried.


Maybe their day hadn’t turned out exactly how he had envisioned it.




Izuku never asked Hisashi or Inko again to take him to the world of humans, almost as if he wasn’t interested in meeting them. He kept his nose buried in history books of the strange humans. He studied his magic and when he presented as an alpha, he worked with his magic on shapeshifting.


Hisashi marveled in how his son could turn into a fire-breathing dragon with a few incantations. Izuku standing with a rag to cover his bits in front of his mother whose eyes filled with tears at how quickly her only child was growing up.


Izuku would make a great demon king. Now if only he was more interested in meeting humans than learning about them from books.




The humans had done it again, ventured too close to his territory, taken his animals to kill and go feast on. Granted, they were cows, pigs, and horses that Izuku took from a village because of how dirty they kept their pens, how sickly the animals looked in the hands of the human. The human soldiers injured a couple of the nymphs that giggled and played in the ponds near his castle, they had tried to run and their mossy hair was yanked back. Despite being a demon himself, Izuku thought of them as the real savages. He had seen how they treat their own kind, the power struggle, the poverty, the pain of mothers and children. Even worse amongst omegas, how they were sold and taken by the next brute they stumbled upon.


He had thought many times of conquering the human world. Izuku had thought for years on end how he would create a new structure for each gender, that omegas and betas alike could choose who they mated and bore children for. How alphas would be put in their rightful places, brought down from their accidentally bitty place.


Each time, something one of the idiotic human kings making a little more hatred for the humans fill his demon heart. His father would scold him if he could hear what Izuku thought.


He knew their primitive tongue, listened carefully as they made crude jokes at his translator, Shouto. One of the only half-demons who had survived long in the human world, finding refuge in Izuku’s kingdom. The demon boy scowling at them, though their words persisted.  Izuku decided to let them continue to suffer, he cared little, only wanted to help in a way that would profit him the most. Help himself in a way that they would stop raiding his luscious lands, to stop them from hurting the creatures of his kingdom.


His hand laid on the nymph's cheek, her soft blue skin warm under his hand, a nasty gash on her cheek. Izuku’s hand glowed for a moment as he healed her, she bowed her head and ran over with the other water creatures. He watched at how happily they took her back to the waters. How could humans see those peaceful beings and think immediately that they were harmful, think to even harm the nymphs?


Every year the humans grew braver, settling their villages closer and closer to his forest. He had commanded long ago that as long as the humans did not enter his lands, they should not be harmed. This time they escaped, most of them at least, his furries beasts eating away at the remains of armored soldiers. He picked up a broken chest piece, he recognized the sigil that was pressed into the metal, a kingdom only a moment away by the portal. Days away by horseback for those soldiers. Izuku would wait until they returned to their kingdom, he sent three-eyed crows to watch the men. They would notify him and when they did, Izuku would stand before their old king and see what could be fixed.


Though, Izuku had to admit…


He mostly just wanted to cause havoc.




“Your soldiers have stolen from us. They have hurt the creatures of the Demon Kingdom.” The demon boy loudly said, he stood to the side. Izuku and the human king staring face to face. The man on his throne, Izuku standing nearly 30 feet away. The guards and knights stood too close to their cowardly king, even if they tried to protect the old man, they stood no chance against the demon king.


The old king was pissing himself, fear so pungent that Izuku wished to gag. He had opened the portal in the center of the throne room, the old kings scared to cry and the gasps of the room were what Izuku he heard first. His green eyes surrounded in black, his twisted black and greenhorns large and powerful, his demons armor, his magical power. All of it letting the crowd know exactly who he was, the king said nothing as the demon translator began to speak.


Tell him he must pay a price, I won’t tolerate the humans trespassing or stealing from me,” Izuku spoke in his native tongue, amusing in the least how humans eyes bulge at possibly hearing a high born demon speak. The boy nodded and repeated it to the human king, who stumbled over his words.


“The men who trespassed will be punished! Please, I ask you to leave us, my people have done nothing wrong!”


Shouto made a show of speaking in a demon tongue.


“He’s groveling, I think you should kill him, he reeks of livestock.”


“Now, now, tell him I’ll return during the next full moon. That he offers what he deems worthy for the crimes of his soldiers.”


Shouto scowled and told the human king, the old man stuttering and sweating as Izuku and Shouto walked through a portal. The demons left them all alone, heavy thoughts on what would even be worthy as payment for a demon king.




Izuku did as he promised, he returned the night of the full moon. The king had amassed a large pile of worthless golds and silvers, horses and cows. Izuku sighed and let his eyes wander over the pile.


Tell him they’ll burn tonight…”


Shouto nodded and told the human king who cried out, shaking his head.


“Wait! Please! We offer one last gift! We hope it is to your liking, King of Demons!”


The king waved over some guards, who nodded and left Izuku’s sights. The alpha men return quickly, they dragged a human boy, who is tied in ropes, dressed in sheer clothing, gag over his mouth but the way he pulled and resisted against his restraints had Izuku guessing what profanities the boy would shout. Though, the captured boy was a beauty amongst every human present.


Blond as the sun, eyes red as blood.


A human slave. Recently captured by the looks of the marks on his wrists, the marks on his ankles. Izuku can already smell that the boy is an omega as well, no older than 15 or 16 human years.


The human king thinks he has pleaded the demon king with the offering of an omega, he had assumed correctly in guessing Izuku was an alpha.


Izuku wanted to rescue the omega, if there was something he despised more than having his territory trampled on. It was the mistreatment of omegas, such beautiful and gorgeous creatures treated like animals, like breeding livestock.


“He is untouched! He will do well to please you!”


Izuku growled at the human king who got too close to the human boy, anger as his fangs dug into his lip as the old man grabbed the slave's chin roughly to properly show his face to the demon king.


Izuku moved in a swift motion, the human king’s hand on the floor. The human king screaming and holding his handless arm, guards drawing their blades but they did not move in advance of the demon king.


The slave boy stared up at him, red eyes continuously glaring. Izuku grabbed the boy's restraints and opened a portal, his words reaching Shouto.


“Burn it all to the ground.”




The boy fought back when a couple of servant demons took his clothes off, stripping him for a bath under Izuku’s command. Izuku couldn’t help but be a bit amused, usually, humans were frozen with fear.


“Get off me! Don’t touch me!” The boy was relentless and one of the servants gave Izuku a deadpan look. The demon king nodded and waved them away, the human boy scurrying to pick up his clothes. Izuku touched the tub with his clawed hand, the water was warm but it wouldn’t stay like that for long. The blond kept Izuku in his sights, watching his every move, pressing himself against the wall as the demon king came closer. “D-Don’t touch me!”


Izuku touched him anyways, letting droplets of water touch the boy's cheek. The blond blinked and slapped the man’s hand away, glaring at him and rubbing his wet cheek.


Izuku tilted his head and looked back at the tub, using a bit of magic to bring a goblet size of water towards them, dropping it on the boys head. The boy blinked and looked surprised, he was drenched now. He looked at Izuku again, questioning his motives.


Izuku brought another goblet of water and dropped it over the boy's shoulders this time.


Red eyes never leaving him as he continued to do so, little bits of water splashing and hitting Izuku’s armor. He was washing away any dirt to get a better look at any injuries, they needed to be healed immediately, he didn’t need the human boy to get infections. He reached down and held onto the boy's wrist, even as he tried to pull away, Izuku didn’t let him. He healed the raw skin and the boy stopped struggling, his eyes wide as he looked down where they touched. Izuku easily got a hold of the other wrist and did the same.


His clawed hand trailed over the boy's ribs, a nasty bruise vanishing, over his cheek, a small cut disappearing. This was as far as he tested the waters, not wanting to push the boy any further, he didn’t need the human omega to panic on him over being touched too much. He stepped back and left, letting the servant demons deal with the more calmed slave.




Izuku learned the boy's name, asking an enchanted book of whatever he pleased to know.




Katsuki had no surname, as many slaves don’t. He did not ask the book anything more, he closed it and traced the intricate patterns on the cover. He was curious about this human, he had learned much about alphas and betas, omegas were a rarer gender. Even if they were in scriptures and books, the telling of them was that they were nymphomaniacs, sex-crazed beings. The symptoms similar to that of an Alpha’s rut, why was it different? Humans had their cycles much too often. Izuku experienced rut possibly once or twice every two years, he knew of other omega demons that would have similar cycles.


Human omegas had their heat every month regularly. Human alphas had their rut every two months. Even beta humans experienced weeks in the year where their fertility rates shot up, though that seemed much better than how the two other genders had it.


He knew humans lived much shorter lives but it seemed more of a hindrance than anything. He couldn’t imagine the anguish.


Izuku looked up, his chamber door opening and a fluffy headed Katsuki was ushered in. The slave boy’s previous clothing no longer in sight, the servants had dressed him in much more appropriate clothing. Instead of sheer skirts and shirt, he was dressed in black pants and a shirt that covered some of his chest. The demons green eyes fell towards the claiming collar the human boy still wore, something for the demon king to tear off and to find new skin to sink his teeth into.


The slave glaring at Izuku as soon as their eyes met. He thanked the servants, they gave the human boy a weary look and left. Izuku wanted for them to leave then turned back to his desk to think, he could hear the human slowly begin to pad around the room. Izuku could imagine what he was looking at, decorative weapons, the horns of a dragon planted on the wall, wings of beautiful fairies in glass displays. All collections for the hundreds of years Izuku had lived.


Izuku wanted to know what the human would do, almost wondered if the human would try and fight him. He had forgone his armor in his chambers, if the human managed to grab on his weapons that hung on the wall. Katsuki could scratch him if he tried hard enough. It would be entertaining, to say the least.


“What are you going to do with me?”  


Izuku turned his head towards the omega and raised an eyebrow, he had no reason to respond to the human boy. It would be much more interesting if the boy thought he couldn’t understand his primitive language. Katsuki glared at him, fists balled at his sides as Izuku kept the air of silence around him. Those red eyes were rather beautiful, if they were the eyes of an alpha, Izuku would hesitate to keep them in a jar for his collection.


“Answer me! I asked — What are you doing?” Katsuki took a step back as Izuku moved in an instant, standing in front of the omega, holding his chin up to look at the demon. “L-Let go!”


His voice cracked as he tried to pull away but being touched again by the demon made his body freeze up in fear and shock. Izuku knew he was double the threat for the boy, a demon and an alpha. Izuku’s head motioned to the bed and Katsuki followed his eyes, face flushing as he turned back to the demon, new fears emitting off him in waves of scent.


“You’re fucking crazy! I’m not getting into bed with you!”


Izuku sighed and rolled his eyes, he reached down and picked the boy up, placing the lean body over his shoulder and walking to the bed in long strides. Katsuki let out screams, kicking and bringing his fists down on Izuku’s back.


The demon king dropped the boy on the bed, watching him scramble to the other side of the bed, away from the demon, watching with wide eyes. Izuku pointed at the bed and walked back to his desk, sitting down and looking over his scriptures again.


“What…” Izuku heard Katsuki mumble from the bed, but he didn’t hear the bed creak or anymore shuffling to signify that the boy got off the bed.


Izuku would use magic to place books back on the shelves, bringing new books to look over. An hour passed and when he turned his head towards the bed, Katsuki was glaring at him, his legs from to his chest, his chin resting on his knees. But his eyes were heavy, his shoulders slumped and Izuku could almost smell how drowsy the omega was.


“Are you scared?”


Katsuki didn’t reply, how could he? He didn’t understand that demonic language. Izuku understood human language, though he was sure his dialect would be too strange for the human to understand. If he practiced when he was younger like his father wanted then maybe he’d communicate easily. Izuku said nothing else and went back to reading.




Izuku read on foods that were more beneficial to humans, Katsuki was rather thin, extremely so. The demon king decided if he was going to keep the human boy, might as well keep him nice and well-fed. It would be up to Katsuki to eat though, by the behavior the omega had kept, it didn’t look like he would be subservient to anyone, not even Izuku. Light began to glow in the room, it was dawn and Izuku had sat all night reading.


He looked over and was glad to see Katsuki still sleeping, the boy falling asleep against the pillows sometime in the night. Izuku had decided that he would make the most of this situation, learn of omega behaviors and their cycles from an omegas point of view. Books were useless, written by alphas who wrote a perverse and delusional version of omegas.


Izuku wanted to write books and educate other curious demons, wanted to fill his father’s journals on pieces of missing information.


The demon king made up his mind.


He would hold on and learn from this human boy for as long as he could.