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Backtracking

Summary:

Zenitsu keeps experiencing these weird dreams, and once he finally wakes up, he finds that everything he once knew was now different. What's worse is that he has no idea how he got here.

An AU where Zenitsu from Kimetsu Gakuen timeline is brought back into the canon timeline and takes the place of his past self.

Notes:

(See the end of the work for notes.)

Chapter 1: Chapter 1

Chapter Text

Where am I?

 

Zenitsu looked around, noticing he was somewhere he had never been before with his Gramps. This must be a dream, he mused. It looked like he was in some sort of backyard, a peach tree not too far in the distance. In his hands gripped tightly was a wooden sword. What was he wearing? He’d never seen that golden and white triangle haori anywhere in his life, where did he get that from? Why was he holding a wooden sword for? Was this some kind of punishment for complaining about kendo practise? He watched and listened to his Gramps speak. Woah, what happened to Gramps’ leg? And what was he going on about. Thunder breathing? What the hell is that? Maybe it was some kind of special technique for kendo, but why would he be using a sword? He watched himself as he switched into some kind of pose, one leg extended behind him as he took a large breath. What was he doing? Maybe he’d stayed up too late watching action movies again and this was the result. Besides a change in pose, nothing seemed to be happening. Until, his vision turned stark white with the booming crackle of thunder.

 

With eyes opening wide along with a gasp, Zenitsu woke up from his dream. Calming his breathing, which he struggled to do as it hurt for some reason, he turned his head to the side to check the time on his digital alarm clock. However, all that greeted him were tidy well made beds with white sheets. Was he in some kind of hospital? While that would make sense as he did remember passing out, for him exclusively it didn’t because he passes out a lot and he’s never been taken to the hospital because of it. As he scanned the walls of the room, he was surprised to find no clock on the wall. That’s weird… He sat up, an instant rush of nausea and dizziness hitting him like a bus. He was starting to get nervous, where was he? The more he became aware of his surroundings, the more he realised it didn’t look like a hospital and that he’s not quite sure where he was. He attempted to get out of the bed he was lying on, but as soon as he stood on his two feet his shaky legs decided they couldn’t support him. He abruptly fell to the floor, groaning and reaching a hand up to his throbbing head, but surprisingly instead of only hair he also felt something like… a bandage? Did he fall and hurt his head? Also, why did he feel so sick? He didn’t remember feeling sick earlier that day.

 

Feeling his stomach drop and a cold chill run through his abnormally warm body, he realised that he was going to throw up. Frantically searching for something to throw up in so he didn’t just vomit all over the floor, he found what looked like a bin in the corner of the room. He shakily crawled towards it, his sweaty palms comforted by the cool wooden planks on the floor. He made it just in time, hunching over the bin as he hurled up whatever he had eaten in the last few hours. He seriously apologised to whoever’s bin this was, but it was either this or the floor. He promised once he was feeling better that he’d clean this up. After retching for a little bit over the bin, he felt his vision start to blurr. Right before he fell unconscious he heard the sound of the door opening and distinctly familiar voices filtering into the room.

 

Another weird dream? He thought to himself.

 

Instead of being with his Gramps in the place from before, he seemed to be walking on a dirt pathway alone. He was wearing that same haori from before and some kind of black uniform underneath he had never seen before. Wait, was that a sword attached to his side? Was this some form of continuation from the last dream, or did he just have an obsession with swords? He never knew he’d dream himself to be a swordsman, but then again, dreams never quite made sense anyway. He noticed that on top of his head, using his head of blonde hair as a bird's nest, was a little sparrow. Even weirder, he seemed to be talking to it, whining about something or other. Zenitsu had always wanted a bird, not having put so much thought to narrow it down to what bird, but he was never allowed one due to already having enough responsibilities. Seems like dream Zenitsu got his wish fulfilled unlike he did in real life. He watched as the sparrow chirped back responses, sometimes pecking him if it didn’t appreciate his words. Huh, maybe he got his wish fulfilled but it turns out the bird wasn’t as nice as he had thought. Something must have happened to dream Zenitsu because he suddenly broke down, crying loudly out of nowhere. He wanted to know what caused this, but he didn’t get the chance as he was once again taken away from his dreams.

 

This time when Zenitsu woke up, it was dark, the only light provided by the moonlight shining through the windows. How long had he been sleeping for? He wasn’t sure. He noticed he was still in the same room as before, but instead of the beds being empty he saw two figures sleeping. Two very, very familiar people with very familiar heartbeats to match. What were Inosuke and Tanjirou doing here? Where are they? Something besides Inosuke caught his eye and once he realised what it was, he couldn’t help but be slightly disturbed. What is that ugly furry mask? Was it supposed to be a boar? And why were its eyes so creepy, it feels like they were staring into his soul. Looking away with a shiver, Zenitsu tested his luck by trying to stand. He didn’t feel as ill compared to the last time he was awake, although he still felt a bit faint and had a pounding headache. Luckily, he wasn’t as shaky as last time and he managed to stay on his own two feet. 

 

Confident that he won’t crumble to the floor, he once again gave his friends his attention, mulling over his situation. He wanted to ask them what was going on but he’d feel bad if he woke either of them up. He didn’t want to bother them, he was already annoying enough to deal with. However, he had no idea where he was and he wasn’t sure if it was okay to go walking around. Deciding that he didn’t really want to take a chance with either option until he could figure out where he was, he walked up to one of the windows and stared outside. It seemed to be a garden outside, quite expansive and well kept. He wanted to go outside and walk around as some fresh air might do him some good but ultimately decided against it. He didn’t feel comfortable wandering around a place he didn’t know. He sighed, maybe he should just go back to sleep? It’s not like he had much of a choice unless he wanted to wake either Tanjirou or Inosuke, which he doesn’t want to disturb them. With that in mind, he laid back down in his bed with his eyes on the ceiling until his consciousness slowly drifted once more.

 

He wasn’t alone in this dream, but he wasn’t with Gramps. This time, Zenitsu was walking beside Tanjirou, both of them talking words that sounded muffled for some strange reason. He looked the same as the previous dreams, but Tanjirou looked slightly different than in real life. He also was wearing that black uniform with a black and green checkered haori, a box adorning his back. He wonders what's in the box. Despite all noises in this dream being muffled, the scratching coming from the box was ever so clear. Why did Tanjirou have a box? Why was he even questioning his dreams anymore? Zenitsu noticed he appeared to have been crying, face twisted in a pitiful expression. This didn’t surprise him in the slightest, he had a tendency to cry a lot so this was not out of the ordinary. He watched as he and Tanjirou conversed, unable to decipher what was being said. 

 

Eventually, Tanjirou reached into his haori and pulled out a single onigiri, handing it to Zenitsu. Wow, even dream Tanjirou was too nice to dream Zenitsu. He watched as he took a bite, then seemed to say something. With whatever asked being responded with Tanjirou shaking his head, he watched as he split the rice ball in half and handed it to the redhead. The redhead responded with his regular cheery smile. The first dream was kind of interesting, but honestly? The last two have been quite mundane. He never thought he’d dream about him and Tanjirou sharing a rice ball, but here he is. He heard a noise from above, seeing a crow cawing out something that, despite the distorted sound in this dream, sounded like words. A crow? Talking? What is this, some sort of fable? He watched as both he and Tanjirou were heading somewhere, running out of view as the dream started to vanish.

 

When Zenitsu awoke this time, he was once again alone. It was bright in the room, therefore leading him to believe it must be sometime within the day, probably morning because he’s never been one to stay asleep for a long time. How long has he been in this place? Was he hallucinating or something? Last thing he remembered, he was on the rooftop of the school building waiting for everyone to eat lunch before passing out, so he still has no idea why he’s here. Also these dreams, he’s never regularly had dreams as he’s never able to sleep for long amounts of time, and when he did have a dream he could hardly remember them. These recent dreams, however, were different. It was almost uncanny the amount of detail he could remember, almost as if he was there. Most of them weren’t anything interesting either, so why? Everything was too perplexing, overloading his brain with unanswerable questions. 

 

He sat up, head turning to the approaching heartbeats. He should be relieved, finally able to ask where he was, but instead he felt apprehensive. What's worse is he didn’t know why and he didn’t get time to mull over it. The door to the room opened, behind it was Tanjirou, Aoi and Inosuke chatting about something. This ceased as soon as their eyes laid upon him. With just one blink, Tanjirou and Inosuke were standing by his side, the sound of relief overwhelming in strength.

 

“I’ll go get Shinobu,” Aoi said to the boys before leaving. Shinobu? Why would she go get Shinobu?

 

“I’m glad you’re awake, we were getting worried.” Zenitsu was snapped out of his thoughts, directing his attention to Tanjirou. His eyes widened and face paled, reaching out a shaky hand to weakly grip on to the sleeve of Tanjirou’s checkered haori. He was wearing the exact same clothes from in the dream, how was that possible? He’d never seen these clothes before, how did he know Tanjirou would be wearing them? Also, aren’t they a bit outdated? Tanjirou looked down at him, tilting his head in confusion. “Zenitsu? Are you okay?”

 

“Where… Where are we?” Maybe this had a good explanation if he knew where he was? His eyes trailed to Inosuke, the mask that had been besides him the other night now placed over his head. It freaked him out, he’d never seen Inosuke have this mask before. Sure, he never followed the dress code as he never buttoned up his shirt properly but this was new. Everything was unnatural, was this also a dream? But it wasn’t like his other ones. He wasn’t watching himself from the outside.

 

“We’re at the Butterfly estate, I carried you here after we fought with that demon.” Zenitsu blinked at Tanjirou’s explanation, hearing Inosuke mutter angrily ‘damn demon, I’ll cut it down if I see it again. No one beats the great Inosuke.’

 

“Eh?” He wasn’t able to say anything to what was being said, it was just so… absurd. He’d never heard his friends speak this way before. Where the hell was the Butterfly estate? He’s never heard of that place in his life. Also demons? What were they going on about, was it some sort of nickname for something? He pinched himself for good measure, just a harmless test to prove he was dreaming, but the dull pain in return only furthered the realisation that this was indeed reality. “Demon?” It was all he could manage to question.

 

Tanjirou opened his mouth to speak, but was cut off when Aoi and Shinobu entered the room. “Ah Zenitsu, you’re finally awake,” her smile was just as pretty as usual but the underlying rage vaguely burning in her heartbeat made him nervous. Her attitude seemed the same but he’s never heard that undertone so strongly in her heartbeat before, it terrified him.

 

“How are you feeling?”

 

How should he respond? No, he obviously wasn’t okay when it came to the mental department but physically he felt okay. Definitely not one hundred percent but way better compared to the previous times he was awake.

 

“My head hurts.” She stared right at him and Zenitsu felt all the eyes in the room were on him as if he was being observed. Were they expecting a different response? He didn’t know what they were looking for, but whatever he said must not have been it. Maybe they expected him to whine about how painful everything was. Actually, that’s probably how he usually would have acted but at the moment he was struggling to think normally. The more his brain caught up to the current circumstance he was in, the more disconcerting everything became. He could never imagine that this situation would occur in real life.

 

“Nothing else? No side effects?”

 

“Side… effects? From what?” Despite the smile, he could hear the frustration coming from the woman by the door. He wasn’t acting ignorant on purpose, he just genuinely didn’t know what was going on.

 

“From the blood demon art. Do you feel any different?” He involuntarily felt his breathing pick up its pace, too many thoughts plaguing his poor mind. This had to be some cruel joke. What is blood demon art? Why would he be affected by it? Did it have something to do with the demon Tanjirou mentioned earlier? He didn’t understand what sort of demon they meant. Were they referring to a person? He slowly felt himself submit to his crushing anxiety, and his thoughts that were begging to be said were finally let free in the form of panicked, fast paced shouting along with frustrated tears.

 

“Blood demon art? I don’t know what you’re talking about! I don’t know anything about what this ‘demon’ is! I don’t know what’s going on, I don’t know where I am, I don’t… I don’t understand! You’re all acting weird and it’s scaring me! Please stop, it’s not funny!” Clearly no one expected him to break into hysterics judging by the looks he was receiving. He couldn’t even manage to speak anymore, struggling to breathe from the intensity of his crying. His head felt like someone was smashing it with a hammer from the strength of his distress. Caught up in his breakdown, he didn’t notice Shinobu leading everyone but herself out of the room to give him space.

 

With everyone now gone, Shinobu returned to his side and placed a hand on his shoulder, squeezing it firmly to grab his attention. Eyes now on her, he watched as she had exaggerated deep, calm breaths, the hand placed on his shoulder hinting for him to mimic her. So he tried, slowly past his haze of pressing worries, his unbearable headache and his never ending tears, to copy her. After a while he felt like he could finally breathe, his shaking shoulders ceased and his insurmountable troubles and pain faded ever so slightly.

 

Out of his thoughts and now aware of the present, he stared tearily at Shinobu in confusion as she retracted her hand and closed her eyes, taking one final deep breath. “Agatsuma.” He flinched from the tone, looking away in embarrassment. Did he really just have a mental breakdown in front of everyone? Wow, he really is pathetic. He could see her smiling once again in the corner of his eyes, but she sounded anything but happy. “What’s the last thing you remember before you woke up here?” He repressed the last of his urgent worries and emotions so he could try and answer her without bursting into tears.

 

“I was on the rooftop of the school building waiting for everyone to eat lunch and then I passed out…” The more he tried to recall that memory, the more hazy it became. Is that all that really happened? He usually had a reason for passing out, but he can’t seem to remember why. Shinobu’s smile never wavered, but her sound did, and it made a sickly feeling start to clog up in the bottom of his throat.

 

“Who were you waiting for?”

 

“My friends, like usual. You know, Tanjirou, Inosuke, Genya, Kanao. Most of them are really Tanjirou’s friends, not mine, but we all usually sit together.” As he listed off the names, that sound only grew stronger. It was starting to become overwhelming, he wished it would stop. Shinobu seemed to be at a loss for words, the silence becoming more dense as time passed.

 

“I see.” She responded calmly but her heart betrayed her. He really wished he couldn’t hear heartbeats right now. She seemed to be contemplating her next words. He couldn’t help but feel somewhat comforted and uneasy by the fact that she also seemed to be struggling to understand what was happening. 

 

“Do you know what a demon is?” He knew just by the tone of this bizarre question that these questions wouldn’t end any time soon. He just hoped everything would be explained, he’s not sure he can cope being this worried and confused for much longer.