Demon Slayer AU

By: FunahoMisaki

(A/N: I own nothing and it was just a little blurb that hit me so I had to write it. Maybe a bit OOC.)

"Let's see this demons true self." Some asshole pillar covered in scars was saying as he splattered his blood on the box Nezuko was in until she popped her head up and stared at him.

"Leave my sister alone! She doesn't eat people or drink blood!" Tanjiro said even as he was pushed down in a way where if he tried to use any of the breathing techniques his chest would explode.

"Then this should be alright then right?" The butterfly looking lady asked smiling coldly but Tanjiro could smell the anger and hatred coming from her and almost all of the Pillars as they all watched and prepared to strike Nezuko down the moment she drank the marechi blood being shoved in her face.

She instead made an annoyed noise and turned her head away from the blood, staring angrily at the person holding down her brother.

"She turned away from marechi blood?" The other pillars were stunned while the heir of the head relayed what happened to his father.

"Nezuko." Tanjiro was relieved and managed to buck off the pillar holding him down thanks to the mans surprise and disbelief over Nezuko turning away from the blood.

Nezuko curled back up in her box sulkily glaring at the stunned pillars but she brightened up and waved slightly at Giyuu who looked surprised but gave her a small wave in return.

"Pardon my intrusion." Tamayo however was entering the shaded part of the room and rushed over to tend to the pillars cut open arm.

"Despite the wisteria around here protecting you and the sunlight you'll still attract many demons if you just continue to bleed." Tamayo scolded the pillar slightly as she began to wrap his wound up and stop the bleeding.

"You're a demon!" The man, what his name was Tanjiro didn't know and he didn't care, as he swung his sword towards her.

"Pardon my rudeness!" Tanjiro blurted out to Kagaya as he raced forward with the hilt of his broken sword in hand and he intercepted the sword aimed at Tamayo. Doing so by twisting his sword handle and what little was left of the blade down towards his own arm so that it was what the Pillars sword hit as Tanjiro thrust his arm in the path of the sword.

"Ouch." Tanjiro winced a little bit as his sword broke further under the force of the blow and some of the metal pierced his arm but thankfully it had parried the other sword and caused the pillar to stumble back in surprise.

His only warning was a flashing of slit purple eyes before a slim foot slammed into his stomach and sent him flying back out into the other Pillars who had stood up in alarm. Nezuko was growling slightly behind her bamboo gag as she glared at them while standing protectively in front of her brother and his wife with her eyes slit.

"Are you alright Tamayo?" Tanjiro didn't care about his arm and the pain it was in as he stared at his wife who was immediately treating his injuries as she pulled the shards out of his arm.

"I'm perfectly fine dear but you were injured. Just after such a rough battle as well. You know that blade wasn't aimed at my neck so why did you…" Tamayo trialed off as she stared at the slayer while he merely smiled brightly at her and leaned forward enough to give her a chaste kiss.

"Pillar or not I'm not letting anyone hurt my wife." Tanjiro said and she blushed slightly but smiled, she was getting used to him giving her affection and kisses with others around.

"You should be more careful dear. Neither Nezuko nor I like you getting hurt either." Tamayo said chiding him slightly while the pillars were all standing with swords drawn but they were frozen as they stared at the couple.

"It's nice to finally meet you in person Tamayo-san. I am Ubuyashiki Kagaya, the current head of the family and Demon Slayer Corps." Kagaya said turning slightly towards the demon doctor who gave him a small smile and bowed respectfully.

"It is nice to meet you Ubuyashiki-sama. You look a lot like your ancestor. Pardon my intrusion." Tamayo said politely and the man merely chuckled a bit.

"You are welcome here Tamayo-san. I see that there is a lot between you and young Tanjiro-kun and this explains Ozaki-chan's report about how a purple eyed demoness and a whitish haired demon had cut the strings holding her and some others captive before their necks were broken by the puppet master." Kagaya said and Tamayo nodded slightly.

"I hope the poor dear is okay. I treated her broken bones as best as I could at the time but it was far from my best work." Tamayo said looking concerned and Kagaya smiled.

"I have been assured that while there is some permanent damage in her off hand, her main arm and hand will recover completely in time. Unfortunately some of the others were not so lucky." Kagaya said and Tamayo closed her eyes slightly with a nod of her head. She had known upon seeing some of them that they were beyond saving but it always hurt to hear it.

"I am sorry for your loss." Tamayo said and Kagaya merely nodded his thanks.

"Boy. Did you call that demon your wife?" One of the Pillars, a blond haired one, asked staring coldly at Tanjiro and Tamayo while Nezuko seemed to be calmed when her brother patted her head and jumped into Tamayo's arms in her tiny form.

"Tamayo and I are Mates in demon terms, married in human terms. She is my wife and I am her husband." Tanjiro said without hesitation as he raised his head proudly and stared them down, his arm moving out in front of his wife protectively in case they attacked.

"You chose to-"

"Becoming Mates is not something done easily or lightly. A Demon or Demoness's mate is always a human, however since most Demons eat humans you can imagine why even those who find their mates often do not keep them. To even find your mate is a very rare and a very wonderful thing for a Demon, especially one who does not eat humans. To even find out if you are Mates a human must bite a Demons neck, and if the mark does not heal over and vanish then they are mates and the demon must bite the human in turn. You can see how that causes a lot of deaths." Tamayo broke in to begin explaining things to the Pillars as she stepped up a bit and put her hand on Tanjiro's shoulder. Her wedding band was on display, as was the bite mark on her neck and the bite mark on Tanjiros neck.

"We do not get to chose who our Mates are. No one is quite sure how Mates are chosen for each demon. We do not have any control over that at all, just as the human doesn't either. Just know this. I do not like to fight as a rule. I am a doctor not a warrior. That will not stop me from fighting to defend my husband. You do not understand just how all encompassing being Mates is." Tamayo said and her voice was cold as ice but her normal small smile was on her face as she stared them down.

"If anything were to happen to Tanjiro then I will go berserk. I will hunt down the one who took him from me and I will sadistically and gleefully show them just how big of a mistake that was. There would be nothing that would stop me from doing so either. And as soon as I was done exacting proper revenge on the one who took my Mate from me I would step into the sun with a smile on my face in order to end my own life and rejoin him in the beyond. Tanjiro is my everything and the only one who could stop me if I were to ever lose my way." Tamayo said seriously and Tanjiro turned to look at her and then took her free hand in his own as he brought her fingers up to his mouth, kissing her knuckles to get his attention.

"And why should we not kill you both right this moment?" The butterfly woman asked staring coldly at them both with a smile on her lips and her sword in her hand.

"Trust me. It would be most unwise to pick a fight with Tamayo-san." Kagaya wisely advised his Pillars while making sure his son was right by his side just in case.

"The minute you try to do so you'd have to get close to me and cause me to bleed. Which is a mistake since Tanjiro already saved all of your lives once today from that." Tamayo said coldly in return and she could see the flash of confusion in each of their eyes.

"My Blood art is not one that can be turned off. My blood itself, as soon as it leaves my body, already begins releasing the mists and illusions that I use to weave my spells. They effect Demons quite potently…however just breathing in the fumes at all from my blood can be lethal for humans, even Demon Slayers. When Tanjiro intercepted the sword strike aiming at my shoulder earlier he did it not just because he didn't want to see me hurt but also in order to save your lives. Trying to kill me would only release the potent blood fumes from my body no matter where and how you cut me and just one whiff would be enough to kill most humans." Tamayo said and they all were wide eyed at that as they stared at her looking a bit horrified. Especially given how close she was to Kagaya and his son.

"Not just that but I am older than any demon you all have faced in your lives. I am older than Upper Moon One and have had all those years to become stronger and wiser. I am not a fighter but you do pick up some things over the years." Tamayo said with a cold smile to them while they were all wide eyed and a few of them were even trembling slightly, Tanjiro being able to smell their fear and horror at hearing this information.

"Now I'll leave you all to your meeting just remember what I said before you make any rash decisions, especially involving my husband. I'll have Nezuko-chan with me Tanjiro so don't worry about her." Tamayo said looking a lot happier and fonder as she looked at her husband.

"Alright dear. I'll find you as soon as I'm done here. Be good for Tamayo Nezuko-chan." Tanjiro said smiling at her and giving her a quick kiss before kissing the top of his sisters head while she nuzzled him happily and then wrapped her deceptively small arms around Tamayo's neck.

"She's a perfect angle and we both know it." Tamayo said and Tanjiro chuckled slightly while she calmly walked from the room and Tanjiro stepped back into the yard.

"I apologize for her scaring and threatening you all. She is very protective." Tanjiro said bowing slightly to everyone while they all stared at him with stunned eyes.

"Is…Is all of what she said true?" The pinkish haired pillar asked staring at Tanjiro who chuckled slightly and rubbed the back of his neck sheepishly.

"It is. She mentioned being there when Yoriichi nearly defeated Muzan himself and how Yoriichi spared her because there was no need to kill her when she hated Muzan and wanted him dead just as badly if not more so than any Demon Slayer did." Tanjiro said and he smelt their fear spiking. There was a demoness in their HQ who not just had a blood demon art that was lethal to anyone inhaling it but also who was older, and therefore likely stronger, than Upper Moon One?

Fuck. If they set her off then… The devastation she could unleash was…was immense.

"Thank you for your time Tanjiro-kun and your report. I am sorry for how they treated your sister but I'm sure if you two could take out the Moons then they may accept her as one of us." Kagaya said to the boy who smiled brightly at him, and the pure sunshine behind it had all of the Pillars faltering slightly and Kagaya didn't need to be able to see to also falter slightly under the sheer cheer of it.

"Don't worry about it sir. I didn't expect them to accept her or Tamayo or even Yushiro immediately after all. Besides I plan on killing all of the Demon Moons and Muzan himself eventually. And as soon as Tamayo finishes her cure for demons to turn them back to humans things will be a lot easier." Tanjiro said bowing to the man and then turning and leaving to find his wife and sister. There was pure silence behind them for a long moment.

Then a shout of.

"WHAT DO YOU MEAN CURE?!"