Chapter Text
It's been 6 years since the death of Sanemi and Genya's family Sanemi forbidded Genya from being a demon slayer which Genya followed that rule when his brother would leave for a mission Genya stayed home reading books and messing with animals he found or go to village for food and more books.But he did that in the daytime never the night because his brother was strict it was a usual night for Genya his brother out on a mission while he read books but he heard a knock at the door"what the hell who's out this late at night mabye it's Nemi?"Genya thought he got up and open the door only to be met with the sight of tall pale skinned man with black hair and red eyes and dressed fancy.Genya froze in fear the man smirked"You must know what i'am little child i smell stregnth in your blood so you would be a perfect demon"the tall male said.
Genya shoved pass him trying to run but the man tripped causing his head to slam against the wood Genya groaned he was kicked causing him to land in snow"Remember my name child Muzan"the tall man spoke before he shoved his finger into Genya arm pumping blood into his body.That was the last thing Genya heard before he blacked out.
Sanemi was returning home from his mission it was cloudy out so the sun was blocked Sanemi stopped in his track at the famliar scent of blood he ran towards his house he stopped in his tracks seeing Genya on the snow he was bleeding from his forehead and arm the blood was on his kimono "GENYA"Sanemi yelled he ran to him kneeling beside him."How the hell could this happend how did a demon find his home Genya always stayed inside at night so why was he out"Sanemi thought Genya body was still warm Sanemi quickly picked up Genya and put him on his back and ran all he could think was that he had to get Genya to a doctor.
Sanemi's lungs burned he didn't know how the hell Genya survived or why the demon let Genya go he just kept going Genya hand twitched slightly Genya lifted his head from Sanemi's shoulder and growled his eyes were bloodshot he growled at Sanemi"Genya stay still"Sanemi said but Genya try pushing his shoulder and kicking his legs slightly.Sanemi lost balance from Genya moving to much Sanemi gasped he felt Genya slip from his hold he quickly twisted his body reaching out for genya's hand he was able to grab it he pulled Genya to his chest and soften his fall using his sword Genya growled and try shoving him.
Genya was able to get out of his grasp he dashed towards Sanemi,Sanemi got a clear view of genya his hair now had purple tips and his eyes were light purple, Sanemi flipped over his head and landed he then shoved the sword into Genya mouth causing Genya to thrash.Genya growled Sanemi fell on his butt along with genya Sanemi wrapped his legs around Genya waist"The hell he's growing his size"Genya thrashed around growling Sanemi heard the sound of feet agannist snow his eyes widen.Sabito standing in front of him"what are you doing why don't you just slay that demon right there"Sabito said Genya put his hand on the sword trying to pull it out his mouth his eyes shut tight and nose scrunched up.
Sanemi kept a tight hold on the sword so he wasn't able to pull it out"He's my younger brother he'd never kill anyone"Sanemi said Genya kept struggling but eventually gave up because he was exhausted he just stared blankly slightly dozing off Sanemi removed the sword from Genya mouth who just sat there.Sanemi stood up "If you want to get to my brother you'll have to kill me"Sanemi said Sabito sighed he dashed towards Sanemi their sword swinging fast Genya just sitting there until he saw the sword close to Sanemi chest"N-N-Nemi"Genya said he ran towards them.He jumped in front of Sanemi the sword pierced Genya chest he yelled out in pain he grabbed the sword causing his hands to bleed"Genya"Sanemi said in shock Sabito stared in shock Sanemi quickly pulled Sabito sword out of Genya chest shoving Sabito back.
Sanemi caught Genya as he had one of his eyes shut breathing heavily before Genya fell asleep Sabito face straighten"I suggest you tell the corp about your brother cause if they find out themselves you're screwed"Sabito said disappearing Sanemi sighed before putting Genya on his back.He went back to the house and cleaned up Genya and layed him in bed before he went to find bamboo he chopped into mouth size with a purple straps he tied it around Genya's mouth before making a bamboo basket and putting the sleeping demon inside.
Sanemi arrived at the Head quaters he explained to the corps about Genya it was strange to them that Genya slept Shinbou kept Genya in the basmet with a nice futon he slept for 3 years straight Sanemi was now 21 when Genya woke he acted perfectly normal but the problem was Genya height remained the same.First Sanemi thought Genya just didn't get a growth spurt but then Shinbou told him demon's don't age"WHAT SO YOU'RE TELLING ME HE'S STUCK AT 13 UNTIL HE TURNS BACK INTO HUMAN"Sanemi yelled,Genya just looked up at him confused.Shinbou just giggled at Genya's confusion"yes demon's don't age he would be 16 if he hadn't turn into a demon"Shinbou said"he was older than those two twin and now he's a year younger"Sanemi said pointing at Yuichiro and muichiro who Yuichiro being temper-headed brat in Sanemi Pov and Muichiro the clueless one.
Genya just stared at them not really doing anything suddenly Mitsuri busted in"KYAA SANEMI I HEARD YOUR BROTHER HAS FINALLY AWOKEN I'VE WAITED SO LONG"Mitsuri yelled she ran towards Genya and crouched down to Genya's height"Ah his hair is a mess i thought you take care of it Shinbou-san There there little one"Mitsuri said.Genya tilted his head"AH how about i do your hair"Mitsuri said patting his head Genya eye soften showing he smiled Mitsuri smiled back she sat down and Genya sat down in front of her Mitsuri combed and brushed his hair into a ponytail adding a purple flower clip on the side of his hair he hummed happily.
Mitsuri clapped her hands togther"Now look you have the same hair clip as me from now i'll take care of you when Sanemi is gone"Mitsuri exclaimed Genya hummed smiling at her he then turned to his older brother an ran to him and hugged him Sanemi froze Mitsuri stared in shock a long with Shinbou.Sanemi stared for a while before crouching down and hugging Genya back who hummed happily he put his face into Genya shoulder"Genya"Sanemi said as his brother hummed again clinging to him like a child"Don't ever do that again please"Sanemi said softly it was slightly muffled but Genya hummed as an agreement Sanemi picked up Genya who shrunk his size although he was still small already but he shrunk to the size of a toddler to curl up slightly.Genya rested his head on his brother shoulder his hand on Sanemi chest on top of his heart.
Shinbou Mitsuri and Muichiro smiled while Yuichiro stared in shock at how nice Sanemi was being Sanemi sneekly flipped muichiro off not showing Genya that he did it cause he knew Genya would be stubborn and start growling at him Yuichiro was getting ready to pounce on Sanemi but Muichiro held him back.Sabito went down to the basement he smiled upon seeing Genya"oh i see you're awake little one"Sabito smiled and cut his arm with a dagger he had Giyuu who was following behind gasped turning pale"Sabito what the hell"Giyuu said.Genya didn't drool at all he just stared at him blankly before turning the other way wanting to sleep in Sanemi arms"Told you he doesn't react to the smell or sight of blood i tested that when he was asleep he didn't even move or awake"Sanemi said"Sanemi i need some of your brother's blood i need to send this to a friend a i met"Shinbou said.
Sanemi slightly glared before taking Genya arm and pulling it away from his chest and pulled up Genya's sleeve who huffed in annoyance Shinbou stuck a needle into his arm Genya huffed again Shinbou drew blood and pulled the needle out before putting in a box and giving it to her crow who flew away.A few hours pass and it was night some of the hashira were on mission while other went to bed Sanemi ended up changing and falling asleep with Genya who was still in toddler form Genya layed on his back one hand grabbing Sanemi's sleeve and the other on his stomach one of Sanemi's arm wrapped around Genya and the other over Genya's head,Sanemi's head on top of Genya's and Genya's head resting on the pillow under Sanemi head.Kanae smiled she never seen Sanemi this relaxed and happy since Sanemi mostly stayed at the house with Genya.
She watched as Sanemi pulled Genya closer and whisper"Thank you god" Kanae looked Genya"He really does bring out Sanemi's happiness"Kanae thought before turning off the light and leaving when it turned Day Kanao went to go see Genya she looked at Genya seeing Kanae crouched down beside him while Sanemi on a mission.Kanae turned her head"Ah Kanao this is Genya he was supposed to be you're age but he became demon so he's three years younger than you"Kanae said Kanao stared at Genya who stared blankly before waving at her Kanao crouched before putting a finger on Genya forehead pushing it slightly causing Genya to close his eyes and cover his forehead.Kanao tilted her head"I thought you said he was 3 years younger than me was his he so small"Kanao said since Genya only reached her knees"Oh he's just in the form of a toddler i think he likes it that way the only time i've seen him his original height is when he was sleep"Kanae said.
A few weeks passed and Genya went with Sanemi Giyuu Sabito and Shinbou to where the spider family live after hearing a lower moon was their and mutliple demon slayers were dying and disappearing Sanemi decided to bring Genya along because Genya hasn't been out in awhile and kagaya said Genya has strength.Genya jumped out of the box he got from Sabito and grew to his original size and ran beside his brother they stopped seeing a boar head kid kill a demon the boar head turned his head huffing"what in the fuck"Sanemi said.The boar head kid laughed like a maniac"I'm going to slay that newborn demon"the boar head laughed Genya hummed in confusion the boar head ran towards them Sanemi picked up Genya and threw him on his shoulder and ran the boar head try cutting Sanemi ankles"THIS KID IS CRAZY AS HELL"Sanemi said"GIYUU HELP I'M BEING CHASED BY SOME CRAZY ASS KID"Sanemi yelled.Sanemi ended up tripping because of a dumb rock he didn't see"REALLY A FUCKING ROCK"Sanemi thought h Genya fell out of his grasp.
Genya fell onto his back and layed there the boar head stood over him"my name Insouke Hashibira and i kill demon eh why do you look like Tezuko but a male verison and have yellow tips and a bamboo muzzle with purple straps WHATEVER I HATE THINKING"Inosuke yelled he was about to connect his sword with Genya neck.But suddenly he was kicked away and he landed on his stomach above him stood sabito with his foot on Insouke back"It's not nice to hurt an innocent demon"Sabito said Sabito turned his head away from the struggling boar head and turned to Sanemi"Grab your brother and run and don't trip over a rock like a dumbass again" Sabito said.
Sanemi scooped Genya up into his arms carrying him bridle style while Genya just sat there staring blankly Sanemi stopped when he saw a burgandy hair kid and Black hair kid on the ground an a demon's head on floor while Giyuu stood there Sanemi let Genya down about to go check the kids out.Until he heard growling from behind him he turned his heads back to see Genya drooling while staring at the demon girl who's bleeding Genya's eyes shock his hands clenching and unclenching"That what Genya must have the urge for demon blood to devour it"Sanemi said Giyuu and the burgundy head boy eyes widen in fear.Giyuu shielded his sword"Tanjiro protect your sister I've heard of demon slayers like this who can devour demons it seems since he turned into a demon he now has a strong urge to devour a demon"Giyuu said Genya let out a shaking breath.
Genya growled before dashing towards Tanjirou and Nezuko but he was stopped by Sanemi who had his arm in his grasp Genya let out a gasp as he was slightly forced back he growled again Genya struggled more acting just like a demon as Tanjirou stared in horror and held Nezuko close.There was suddenly a tearing sound Genya ripped his arms from Sanemi grasp Sanemi immedatily dropped his arm as they faded into dust Genya's arm immedatily regenrated"SHIT"Sanemi yelled Genya ran Giyuu was close to wrapping his arms around Genya but Genya flipped over him and chased after Tanjiro and Nezuko.Genya reached his hand out his nails expanding even more he was close to grabbing Tanjirou haori but his legs were cut off by the boar head from earlier"Thought you could get away from me peach wasn't able to stop me knocked him out with the hilt of my sword"Inosuke laughed mainacly Genya growled as a blonde showed up"You wont hurt Nezuko or Tanjirou"Zenitsu said.
Genya growled out again his legs regenrating quick he stood up now bare foot he dashed towards them he disappear and reappeared behind Zenitsu and then kicked him in the back before he jumped above Inosuke he was in front of the full moon he twisted his body before raising his leg Inosuke was quick to dodge the attack.Inosuke eyes widen seeing how Genya made a big hole in the ground"if i hadn't move in time he crush me with just a leg"Inosuke thought Genya appearing beside him giving him a death glare sending fear into Inosuke body for the first time Genya kicked him away.Inosuke went flying foward passing Tanjirou and crashing into a tree.
Tanjirou froze"This demon he has power like no other he's like Nezuko a newborn but he attracted to demon blood"Tanjirou thought he used his body as shield covering Nezuko but he didn't feel the impact of Genya kick he turned around his eyes widen Sanemi was in front of him holding Genya leg,Genya try applying pressure but Sanemi didn't move an inch.Sanemi looked up before he pulled Genya towards him Genya gasped Sanemi wrapped his arms around Genya who growled loudly at him trying to squirm away"Genya look at me"Sanemi said Genya looked at him"Remember mrs.Kamado those are her children Remember Nezuko she was your friend Mrs.Kamado gave us blue juice remember"Sanemi said.
Tanjirou stared in shock he remember Sanemi the big asshole who always had random beef with him Genya eye filled with tears"Don't cry it's fine ok"Sanemi said as he hugged his brother who whined slightly Genya randomly started swaying back and fourth before his nails started to retract into small sharp nails and his size shrunk.Sanemi looked in shocked as Genya lay down on the ground a curled up into a ball tears on the side of his eyes Sanemi picked up Genya letting Genya head rest aganist his shoulder his arm under Genya's butt supporting him his other hand on Genya's back"i guess when he uses to much energy he sleeps to regain it"Sanemi said.Genya's arms hung limp Nezuko got out of her brother grasp and ran towards Genya"Nezuko wait"Tanjirou said but Nezuko ignored him.
She looked at Genya face before touching her own bamboo muzzle she reached out to touch Genya's head now remembering him her eyes sparkled she smiled through the bamboo muzzle she tilted her head.She remember Genya playing with her when she was three chasing eachother and all she realized Genya was now just a year older than her and not three years older anymore she hummed Sanemi started walking Tanjirou took Nezuko hand and started walking they reached where Shinbou Sabito and Giyuu was.Sabito was locked under Giyuu's right arm he was struggling to get out but Giyuu just held him"See i told you Nezuko is nice"Giyuu said he then let go of Sabito who smacked him on the back of his head.
Giyuu rubbed his head"Let head back to the head quaters"Sanemi said he put Genya in the box with signature of Genya's name on it Sanemi closed the box he put on his back Nezuko hopped in her box Tanjirou followed them back to the headquater the Kakushi put Inosuke and Zenitsu in the infairmy.When Tanjirou eneter his box was ripped from his back he was pinned and his arms were tied Tanjirou looked in shock they took him and Nezuko Tanjiro and the other hashira were in the sun and Nezuko in the shade Kagaya came out he sat down"Sanemi get your brother to the basement he needs rest we will talk about what happend later"Kagaya said.Sanemi nodded a Kakushi took the box without showing fear and went the basement Sanemi walked in the shade and stab Nezuko box's she let out a pained screamed"WHAT THE HELL ARE YOU DOING"Tanjirou yelled Sanemi put Nezuko's box on the ground he cut his arm letting the blood fall onto the box.
Nezuko box opened and she grew her size she looked up and was drooling Sanemi stood there Nezuko stare"Nezuko"Tanjirou said Nezuko fist clenched she stood there for awhile before turning her head away with her eyes shut"the demon turned away in disgust"One of the twins said Kagaya smiled"she's good meeting dismissed".Shinbou and Mitsuri stood and went to the basement Nezuko huffed and shrunk she huffed angerily at Sanemi before closing her door a Kakushi picked up Tanjirou and another took Nezuko box's Sanemi left to go see what Genya was doing.
Tanjirou sat on his bed Zenitsu taking medcine and Inosuke just staring blankly Nezuko pulled on Tanjirou's clothes pointing to the door Tanjirou was confused Shinbou appeared"she must be looking for Genya"Shinbou said Nezuko nodded she crawled into the box and closed the door Tanjirou picked up the box.He followed Shinbou along with Inosuke and Zenitsu they went down to the basement she opened the door to one of the room in the basement"Ah Genya you're awake"Shinbou said Genya hummed he was sitting there while Mitsuri brushed his hair after washing it.Tanjirou set the box down Zenitsu stared in fear as Genya huffed Nezuko opened her box door she grew her size her eyes lighten up seeing Genya in toddler form she walked to him and sat down Nezuko noticed Genya hair was now out layer she pointed to his hair pin Genya got up and went to Mitsuri he tugged on her clothes.
Mitsuri turned around"Yes little one?"she said he pointed to her hair pin then to Nezuko and hummed"Oh i have more here"She said she handed him a pink one to match Nezuko ribbion Genya walked over to Nezuko she sat down Genya grew his size to his original height and put in her hair.Nezuko made a little chirp noise out of happneiss"Why does he like being so small?"Tanjiro said"Oh he's not that's his regular height"Tanjiro gasped"HE'S THAT SMALL HE'S EVEN A INCH SHORTER THAN TEZUKO"Inosuke said laughing"Why is he so small isn't he our age?"Tanjirou said.Shinbou giggled"Demon's don't age he stuck at age 13 and Nezuko is stuck at age 12"Shinbou said Tanjirou looked in shock he looked back over at Genya who was huffing angerily at Inosuke who kept laughing Genya walked over and kicked the back of Inosuke knee which Inosuke fell"YOU LITTLE SHIT"Inosuke yelled.
Mitsuri laughed"He does still have his brother anger tho"Mitsuri said Sanemi walked in with a watermelon Inosuke was chasing Genya around the room Zenitsu still scared of Genya hiding behind Tanjirou Genya froze which caused Inosuke to fall"Sanemi why do you have a watermelon?"Mitsuri said.Sanemi sighed"I want to see if Genya will eat this"Sanemi said he placed it in front of Genya who sat on the ground Genya sniffed and immedatily started drooling he ripped off the bamboo muzzle which everybody except Nezuko and Sanemi froze in shock Genya then started to try and form word"T-T-Thank Y-ou Nemi"Genya said smiling showing his fangs.Mitsuri almost died for how cute he was being Sanemi smiled as well as Tanjirou and Shinbou Nezuko hummed in frustation before ripping off the bamboo and wanting a slice of the watermelon"Wait let me c-"Before Sanemi could finish Genya dug his nails into the watermelon breaking it in half and handing the other half to Nezuko,Nezuko smiled brightly before throwing a hand up in victory"YAY"she yelled .Tanjirou smiled happy to see his sister eating and hearing her voice Nezuko ripped a piece off and started eating and Genya used his teeth to bite into the red part of the watermelon.
Shinbou looked in shocked at how they were able to eat human food"I'll need a blood sample from both it's strange demons usually find disgust in human food and can't eat it meanwhile these two are eating without disgust or vomiting especially Genya he started drooling just by the smell of watermelon"Shinbou said.She patted Nezuko and Genya head before taking off their shoes and leg wraps she took a sample of blood from both"well i'm off"Shinbou said before running away Nezuko and Genya hummed"It seems both of them broken away from Muzan that's why they can eat human food and don't eat humans"Tanjirou said after the two finished eating their clothes hands and face were messing from eating the watermelon Mitsuri offer to wash Nezuko which Tanjirou gladly accepted.
Sanemi sat Genya in the tub and washed him then sat him on a stool he wash Genya face and hair before dumping water onto Genya's head washing away the soap he then dressed him into a white kimono and white socks he picked up Genya and placed him on the futon and put the bamboo back over his mouth he made sure it was Genya's by checking the straps to make sure it was purple.Genya's body shrunk Tanjirou walked in with Nezuko who was tired and in a form of a toddler"can Nezuko sleep in here?she doesn't want to sleep in the room they made her"Tanjirou said Sanemi sighed before nodding"just place her next to Genya"Tanjirou beamed he picked Nezuko up and place her next to Genya and put a blanket over them Nezuko and Genya immedatily wrapped their arms around each other falling asleep again.
Sanemi and Tanjirou smiled"Seems they really think of eachother as siblings"Tanjirou said"Yeah"Sanemi aggered they went their rooms to sleep people think of Genya and Nezuko as twins since they are so close and people think of Tanjirou and Sanemi as Younger Brother and older brother who always fight.