#Swap!Douma | Explore Tumblr posts and blogs

echantedtoon · 6 months ago

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KNY Swap Au Ramblings P2

I've seen a lot of others make their own versions of a swap au and I wanted to create one too just for fun. None of this is cannon, and not everyone will be swapped out and it'll have my own twists on things. And have some things added for new story elements.

Most of the role swaps I've seen are usually with either Sanemi and Genya or Gyutaro and Ume replacing Nezuko and Tanjiro. Or the rolls are swapped with Tanjiro being the demon instead. But for this I'm swapping out the Kamado Siblings for the Tokito Twins. I won't go into depth about everyone but I will give important differences to the story.

WARNINGS: Mentioning of killing, death, regular demon slayer content, etc.

EDIT: If you don't agree with any of the placements or head cannons that's fine. This is only my take on things.

Some people liked my Swap Demons concept so I decided to do a second but with the Swap Haishira. If you don't agree with the placements or headcannons like before that's fine. And again not everyone will be swapped out or changed.

I based Swap Muzan partially on the swap au headcannons by @demonslayedher on Tumblr.

MASTER MUZAN KIBUTSUJI AND HIS FAMILY:

Honestly not much about him as a person has changed. He's still very much scheming, cunning, smart, strategic, and has a temper. The only difference is that he doesn't really y'know kill, eat, and murder people like Cannon Muzan. He runs the Demon Slayer corps like a smart well oiled machine and somehow he's very good at it. Of course not many people in the corps have the mind to oppose him with his temper and hatred for being tested. Despite his... personality, he's a very efficient planner and more than once some of his plans have worked in stopping demons. Despite his own short comings and the disease he has, his abilities to run the corps effectively has earned him the loyalty of most of the slayers. Even if not everyone likes him as a person they can admit he's an efficient leader. He may not always be understanding but he's smart enough to know how to approach sensitive topics and deal with the consequences that comes with having slayers and being the leader of the corps.

Not much of the disease has changed. The only difference is that he has it in this timeline instead of Kagaya.

His wife, Rei Kibutsuji, is the one who helps run the corps if her husband's disease is too much for him to deal with that day. She was engaged to Muzan when they were both sixteen due to her family's various connections to resources and married at eighteen. Her family's various connections and resources has been a great help to the corps. Providing various medications for them to experiment with to combat the disease plauging the Kibutsuji family for generations, secret hiding courters for various slayers in the areas, Intel, and other things which helps. Her more level headed calm persona often helps to balance her husband's temper and her insight to various situations and things help him to make better choices in some instances. She is almost like a mother figure to the younger slayers in the corps and many respect her opinions on difficult situations.

They both have a single daughter, Muzan's heir, around the age of ten. Not much is known about her but she's very wise for her age and attends the final selection in place of her mother if she cannot spare a moment from her father otherwise she is always by her father's side helping him. Her first name is unknown to everyone but her parents and is a well guarded secret for security measures. Most call her by her given title of 'Young Kibutsuji'.

HAISHIRA DOUMA:

Honestly Douma as a character and personality wise does not change one bit. He is still emotionless, apathetic, and everyone still dislikes him. But his story changes slightly as a slayer. His parents were originally followers of Gyomei's cult and upon his birth believed to be blessed by the gods with such a beautiful child. Thus child Douma became the (sideshow-) poster child whenever his parents went out with others to spread the 'good word' of Gyomei's eternal paradise cult. When he was about 8 the same instances occur in cannon. Douma's mother finds her husband cheating with other follower while out trying to recruit more followers. After killing her husband and his affair partner she took her own life leaving Douma just... standing there. Awkwardly just staring. Before just leaving to just...wonder aimlessly really for a long time until after a long time he's attacked by a demon in the mountains after attempting to seek shelter in a shrine as it was something familiar to him. A fight insued in which he nearly died if Urokodaki hadn't come along, he may be retired but he could still slay a low level demon in self defense if needed. The man is surely confused by why such a young child is here by himself, but is even more shocked by the fact he didn't show any emotion at almost getting killed by a demon. Unsure of what exactly else to do, Urokodaki decides to take him under his wing for now.

Later he did end up later learning water breathing techniques from Urokodaki along with Hakuji, and two other boys named Sabito and Giyuu who both went missing or died in their final selection. During his training Douma has formed a personal breathing style derived from Water Breathing known as Ice breathing which match his cold personality. Strongest Haishira which makes Hakuji angry. Actually was the one who ended up recruiting Gyutaro into the slayers after finding both himself and Ume in the entertainment district during a mission. He doesn't have any real reason to be a slayer other than it gives him some kind of purpose. Personally no one really likes him except for Gyutaro whom is grateful for the help he's received from him. Muzan only hasn't gotten rid of him yet because he's a honestly a very powerful force on the battlefield.

Was actually the one who found the brothers in the mountains while tracking down a powerful demon and took pity on them after seeing Yuichiro's unnatural demon behavior. That's what you're supposed to do right? Help others! He was nearly executed by Akaza for his actions at the next Haishira meeting.

HAISHIRA HAKUJI A.K.A AKAZA:

Not much changes a lot about Akaza's backstory other than instead of poison Koyuki and her father were slain by demons instead of poison. Shocked, in grief, and filled with rage Akaza began hunting demons down on his own. He was unaware that a demon Slayer corps existed at the time until he also ended up just coming across Urokodaki in a similar fashion to how Douma was. Similar to Douma, Akaza developed his own Snow Breathing style derived from water Breathing, and fights a mixture of using his blade and his own physical body up close to deal damage with brass knuckles embedded with Nichirin spikes if demons are close enough. His previous martial art skills helps him to be flexible and untouchable in battle. Despite studying under the same teacher and both having breathing styles derived from water breathing, Akaza HATES Douma. He hates his fake personality and how he acts all buddy, buddy to him. His mission is to eradicate the demon king and avenge Koyuki's death. The most loyal to Master Muzan. Akaza respects his serious attitude and cunning mind.

He thinks Douma sparing Yuichiro and Muichiro was a stupid idea and has mixed feelings about it all. Much rather prefers to be around the Kamado Siblings he himself recruited.

HAISHIRA GYUTARO AND UME:

Gyutaro is actually the Haishira. Ume is works safely at the butterfly mansion with Kanao, Aoi, and Nezuko in care for the slayers and kakushi who need to heal (changing my mind on Aoi and Kanao being demons). Backstory wise everything still proceeds as is cannon. Haishira Douma happened to have stumbled across the two siblings while hunting the previous Lower Moon Three in the area at the time. Feeling sorry for the two, he brought them back with him and sorta just dropped the two in Shinobu's lap. Gyutaro is extremely grateful to Douma for helping him and when the older man expressed interest in Gyutaro's already good fighting skills, he suggested that he join the corps since he has no where else to go. Unfortunately due to Gyutaro's unusual body conditions, he wasn't able to master the breathing styles Douma tried to teach them. Shinobu in a rare form of kindness after seeing Gyutaro interactions with Ume, offered to teach him her Insect Breathing she mastered because her body also isn't as strong as most Haishira. Gyutaro is the Mantis Haishira having previously learnt insecct breathing from Shinobu before her strange disappearance. He fights using his thin but flexible body like a preying mantis striking his prey. His weapons are duel Nichirin scycles custom made from his memories of using them for his job. He is surprisingly very good at killing demons and enjoys his new purpose.

Ume is often wanting to become a slayer like her brother, but Gyutaro forbids it forcing her to stay in the butterfly mansion with the other girls out of harm's way. Not much to say about her. Her whiny personality often collides with Aoi who keeps her spoiled attitude in check when making her help around the mansion while her older brother is out slaying demons. She does get the occasional visit from the Ice Haishira tho it's rare.

RETIRED HAISHIRA NAKIME:

Again not much to say about Nakime. Y'know that guy from Dororo who can use the sword in his biwa? Yeah that's her. Retired Sound Haishira. She can still slay demons with ease however she has retired after killing the Demon Tengen and his wives with a few other Slayers and loosing her eye I the process however she remains behind in the corps to help Urokodaki and others train the new slayer recruits.

HAISHIRA HANTENGU:

Not much is known about the quadruplets and their younger brother. They were all brought in one way or another from a horrible family situation by Rei after their grandfather Hantengu had a mental break and their father Urami just up and left them all.

Sekido is the oldest one and trained with Kaigaku and Zenitsu by gramps and is a few years older than them. He and Kaigaku are always butting heads and tolerates Zenitsu only to an extent because he reminds him a smidge of Aizetsu. But otherwise he dislikes the 'whiny lightning brat'.

Aizetsu is the only current water breathing Haishira after training with Urokodaki and mastering the style. He deals with depression after everything he endured and is always worried about his brothers especially Zohakutan being the youngest.

Karaku is the current Wind Haishira. Self explanatory. Often he's paired with Sekido for missions. Despite the two brothers fighting like cats and dogs with rabies, they are surprisingly very good at fighting together during life or death situations. May or may not have a crush on someone in the corps.

Urogi is the only Hantengu brother who isn't a Haishira or Slayer. He is unable to use any breathing styles unlike his other four brothers. No one is sure why and honestly he's a little disappointed and sad, but he found a good purpose of helping to care for the many messenger crows that the corps uses. He's surprisingly very good with them and even matched many crows with their perfect match in a slayer including all of his brothers and surprisingly Akaza. Is the closest with Zohakutan as he's always the one who constantly keeps tabs on baby bro using his birds. Zoha thinks it's annoying but the comfort of having someone to fall back on for help is comforting to him.

Zohakutan so far is the youngest Haishira only a few years younger than his older brothers at 14. He's developed a breathing style all on his own Nature Breathing after his three Haishira brothers all tried training him in their own breathing styles. Somehow Zoha was able to mix the three plus add his own differences to create his own unique breathing style. It's proved to be very effective against demons. He's very loyal to Master Muzan after he let them stay and takes killing demons very seriously. Possibly more seriously than Sekido and honestly is always trying to surpass his older brothers to prove to them that they don't have to worry about him. Surprisingly he likes Tanjiro and Nezuko. Tanjiro's personality won him over and Nezuko is the little sister he never had. A lot of the time you can find him sparing with Inosuke.

SWORDSMITH GYOKKO:

Gyokko is the swordsmith who's responsible for the strange concoctions of weaponry that the current slayers use and his biggest rival is Haganezuka. While Haganezuka absolutely hates, hates, HATES Gyokko making strange weapons and for constantly tinkering with the 'true beauty of the blade', Gyokko hates that his fellow swordsmiths 'have no artistic creativity!!' Gyokko is the only swordsmith who is willing to 'get creative' and take special requests from his slayers. But because of his attitude like Haganezuka he rarely gets any requests. He personally made Akaza's Nichirin spiked brass knuckles, Douma's Nichirin fans, and Gyutaro's Nichirin scycles as they actually saw an opportunity to use his creative skills. Because of that they're his favorite Haishira but he also gets upset whenever he has to replace the unique creations he made for them. It's unclear if he is the one who made Nakime's biwa sword but as the two older people talk it's not a far off possiblity.

He doesn't just make swords and weapons. Gyokko also dabbled in pottery and has made his own monstrous mask he constantly wears. Douma has expressed the beauty in his pots and was gifted one as a result along with his battle fans. It still sits in his estate. Haganezuka and Gyokko once got into an argument where Haganezuka ended up kicking one of Gyokko's vases destroying it. That resulted in the worst fight the two had up to present day lasting for hours and ended up with both of them needing bed rest for several months. The two swordsmiths are no longer allowed within twenty feet of each other.

DOCTOR ENMU:

Enmu is by far the most hated member of the corps second to Douma...buuuut he knows his way around medicine and he owes a lot of money to Muzan so this is his way of paying it back. Despite his..'quirk' he's a competent doctor and knows a lot about anatomy. Whenever he's given a demon from final selection to disect- Study or is tasked with researching Muzan's blood and skin cells from his sickened skin, he's very creepily excited and motivated. He used to speak to Shinobu about his discoveries from dissecting demons and ask about her wysteria poisoning techniques until her mysterious disappearance. When Shinobu disappeared all of the full nursing duties became his responsibility and he took over the butterfly estate partially run by Aoi. He's since found her notebooks and journals of her experiments and continues her research. Will later assist Tamayo with her cure for demon kind.

He was hoping to study Yuichiro's body if Sekido ended up killing him but unfortunately he wasn't allowed to do anything. Still occasionally asks Muichiro for some of his brother's blood despite his disgust.

TSUNAGU KAIGAKU:

Not much changes about Kaigaku's backstory. He's a few years younger than Sekido and his brothers and two years older than Zohakutan. Like Sekido has mastered enough Thunder Breathing to become Sekido's tsunagu but not by choice. Muzan assigned Kaigaku this placement because Sekido can and WILL scare Kaigaku back into place when his ego goes unchecked including using physical punishment and harsh training when he thinks it's needed. Kaigaku HATES it and Sekido...But it's been effective and he has become more humble and has learnt to not have such a big attitude after Sekido threw him using a single hand to throw him across the room for the fifth time in one day.

Zenitsu and him fight like siblings (see Kimetsu Gauken on this-) but has learnt not to throw things at him anymore after Tanjiro headbutted him and knocked him unconscious for a few hours. Despite that he can tolerate Tanjiro and Zenitsu to an extent but always fights with Inosuke and Zohakutan. He much prefers to go on missions with Kanao and Muichiro if he's supposed to have a partner for missions as they're usually easier for him to go on missions with. Genya is like him so he can somewhat tolerate his presence if he's not being trained by someone else.

Between Sekido's harsh lessons, Muzan's scoldings, and Tanjiro's kind advise(and humbling headbutts) he's learnt to become a bit better as a person. Not a lot but better, and Tanjiro is always trying to be friends with him. There's hope for him yet.

That's it so far for my ideas on some swap Haishira. I might do a third one with my Swap headcannons for the swap Kamaboko squad and Muichiro and Yuichiro if anyone's interested in that.

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