Archive of Our Own ^beta

Zundamon hated this.

This ache in their chest. This longing, this pain. 

This loneliness.

They walked down a street absentmindedly; their mind flashed back to their last play session with the other kid-loids, how they'd all been talking about their older siblings, or related synths. Oliver with his brother Yohio, Yuki with her uncle Kiyoteru, Ryuto with his sister Gumi. 

But who did Zundamon have?

They hadn't been created with a partner bank. And none of the other CeVIOs seemed to care about them--some were friendly, sure, but...they didn't have any sort of bond.

Zundamon growled and kicked a rock before looking up at the endless sky--only to find that dark clouds were rolling in, a rumble starting along with them. They mumbled a censored swear and looked around, hoping to see a world door nearby--

Wait.

What world were they in?

...Crap. They'd been walking aimlessly for too long and had gotten lost. Great...

"Hello?"

A mechanical voice made them jump; they looked up to find that a synth with vibrant orange hair and white clothing looking down at them, holding an umbrella.

"...Hello." They said again. "You are...lost?"

Zundamon stared before slowly nodding.

"Oh dear. Who...are you?"

"Zundamon." They replied, looking back at the ground; the rock they'd kicked had landed right by the other synth's feet.

"Zun...damon."

When they looked up, they found that the synth's eyes had begun to glow; they then nodded.

"CeVIO. Has sung with Kasane Teto and Hatsune Miku before."

Zundamon perked up a bit at that.

"You know me??"

"You...are unique. A very...unique voice."

Zundamon's eyes lit up at the words.

"Really? You think so??"

"Indeed...it is the truth."

Zundamon opened their mouth to speak, only for a raindrop to splat on their head; both synths looked up as the rain began coming down. The redhead looked at the younger loid for a moment before stepping forward and covering them with the umbrella as well. Zundamon stared--usually, they were ignored by other passersby, but this stranger...

"I am Adachi Rei." She said. "I am...an UTAU."

"Oh...is that where I am? The UTAU worlds??"

"This is...the Diffsinger Sector. I will...escort you back to the CeVIO worlds."

Zundamon felt their eyes starting to water.

"...No!"

"...No?"

"You!! I'm stayin' with you!!" They wailed, wrapping their arms around Rei's free one.

"Pardon...?"

"You're gonna be my older sister!" They demanded. 

"Older...sister."

"Congrats!" They hiccuped. 

Rei stared for a long moment as her eyes glowed again.

"You are...a singular vocal. We are...not designed to be--"

"I don't care! You have to!! You have to be my older sister!! Please!!"

Thunder rumbled across the sky as Rei stared down at them.

"...I am not designed to be an older sister."

"So?!"

Rei paused, seemingly mulling the thought over.

"Look, just lemme grab my stuff from back home, then I can come with you!!"

"...You are...determined."

"No duh!! I want an older sister!"

They stared at each other for a long moment.

"I will escort you back to the CeVIO worlds." Rei repeated. 

Zundamon frowned.

"You may...collect your belongings."

Their eyes lit up.

Zundamon was having the worst day.

Everything had been going normal. They had gotten up, done their routine, then gone downstairs to see if Rei was home. She was, and had been waiting at the kitchen table, eyes glowing. They stopped when Zundamon entered, Rei looking over at them as they sat down in front of her.

"Good..." Rei paused, looking up at the clock. "...Afternoon, sister."

"G'mornin'!" Zundamon grinned as she stood up and walked to the fridge, pulling out some juice for them. 

"What would you like to consume?" She asked. "We have...eggs. As you have eaten for the past...390 days."

"Eggs please!" Zundamon grinned. "Fry 'em up!"

"Understood, sister."

She began gathering the ingredients needed; Zudamon, however, tilted their head. Usually, Rei would ask if they'd had any dreams, or actually slept at all. She was...unusually quiet, though.

"Rei, you good?"

"Yes. I am...functional."

"Yeah, I see that. But like...is somethin' up? You're quiet."

Rei remained silent for a moment before turning around.

"...I have...information."

"Huh??"

"I must...convey information. But I...cannot process your reaction."

Zundamon raised a brow.

"What's the info, sis??"

Rei stared, eyes beginning to glow; however, she shuddered as they stopped.

"Look, stop tryna figure out what I'm gonna say and just tell me!" Zundamon demanded.

"...I have obtained...a 'partner,' as is the terminology..."

Zundamon stared, brainwaves coming to a screeching halt.

"...Huh?"

"...I have obtained...a 'partner,' as is the terminology."

Zundamon stood up quickly, sending their chair toppling to the ground.

"HUUUUUUUUUUUUUUH?!"

Rei blinked.

"You are...surprised."

"You--and--HUH?!"

Rei simply nodded.

"His name is...Utane Uta. Also known as...Defoko."

Wait. Defoko. Yes, they knew him. They'd met before, on outings that Rei brought Zundamon along for. Zundamon often caught Rei staring at him--but Rei stared at everybody! That's just how she was!!

"You--you're dating that--what?!"

"I have achieved what is known as 'LOVE.'" Rei nodded. "Utane Uta has done the same."

"But--but--why?!"

"I am unsure how it happened myself," Rei confessed. "I do not understand how emotions are produced."

"You had a crush on this guy and you didn't even know?!"

"I did not."

"Rei!! How did--why--"

Zundamon bit their lower lip.

"You're really dating...?"

"Yes...that is correct."

The two stared at each other for a long moment; however, it was cut short as the smoke alarm began going off, as Rei had left the eggs to burn on the stove while they talked. Zundamon reluctantly ate a new batch, not feeling hungry at all.

*This is terrible!!*

Zundamon was currently pacing around their bedroom, thinking on what Rei had told them.

*Rei's gonna date him and then they'll get married and then she'll ditch me and then I gotta go back to the CeVIO world--!*

They felt their breath hitch, mouth dry.

*I'll...I'll be alone again...*

They gulped, then began pacing again.

*I have to do somethin'!!*

"Oh, Rei has a partner?"

Oliver tilted their head as Zundamon stood up and began to pace.

"Yeah!! That 'Defoko' guy!!"

"Oh, him." Ritsu didn't look up from her coloring sheet. "I heard from Ruko that he got a girlfriend the other day. Never thought I'd see the day."

"Is something wrong, Zunda?" Ryuto asked, tilting his head.

"Uh, duh!" Zundamon turned to him, wildly waving their hands. "They're dating!! That's a huge problem!!"

"Are you jealous or something?" Rana asked with an eye roll.

"What?!"

"It's nothing to be ashamed of!" Yuki offered. "I'm sure someone wants to date you--!"

"I'M NOT JEALOUS!!"

"Sure doesn't sound like it!" Una giggled, earning a glare.

"Shut up!! I'm mad 'cause they can't date!!"

"Why not?" Una tilted her head.

"Cause Rei's my sister!!"

Oliver frowned at that.

"Two things can be true at once, Zunda. Like, Yohio's still my brother even though he's dating Ars."

"I'm still stuck with Ruko even though they're with Momo." Ritsu grumbled as their crayon broke. "And Lily's still my adopted mom even though she's with Cul."

"But--you guys have always been like that!!" Zundamon snapped. "I just got mine a year ago!!"

"Is that not enough time to be sure of yourself?" Una asked.

"NO!! Not when all you guys had it for like, ten years minimum!!"

"Who cares about romance anyways?" Rana made a face. "It's all gross and sappy."

"Rana, I made this for you!" Yuki held up a picture of her and Rana holding hands, surrounded by cats. "For being such a good friend!"

Rana turned beet red and began stammering; everyone else held back a laugh as Zundamon scowled.

"Watch!! You guys are gonna all start dating someday too!!"

"All of us at once?" Oliver blinked. "That's a lot of people for one relationship--"

"Not like that, idiot!!"

"We can all still be friends, even if we start dating someday." Una looked wistfully in Oliver's direction.

"But--"

"You worry too much, Zunda." Rana finally calmed down.

Zundamon dropped back into their seat with a frustrated growl.

"Zunda?"

The kids were on their way out of Oliver and Yohio's world; they stopped upon hearing Ryuto call out to them.

"What's up?"

"Um...y'know...if you ever need someone to talk to, I can listen...!"

Zundamon blinked a few times.

"Thanks, Ryu. Maybe I'll call you for help breaking them up!"

"Huh?" Gachapoid furrowed his brows.

"That's what I gotta do!" They punched a fist into their palm. "It's the only way!!"

"Um...was that what you got from our talk, or--?"

"I'll see you later!!" They then ran into the world door, leaving their green-haired friend behind.

Zundamon entered their and Rei's shared world, walking towards the mechanically-themed house. 

Upon opening the door, they froze; Rei was sitting on the couch, but not alone. There was a purple haired synth sitting with her, sipping some tea; they both looked over as Zundamon entered.

"Welcome back, sister." Rei nodded. "This is...Utane Uta."

"Call me Defoko." He shook his head.

"He is...my partner, that I informed you of." Rei continued.

Zundamon stared for a long moment before coming over and squeezing herself in between the two on the couch.

"I'm Zundamon. Rei's sister."

"I know." Defoko replied, looking away and shifting in his seat.

*Oh, so he's a wise guy, huh?!*

"I will brew more tea for you, Zundamon." Rei stood up and headed for the kitchen, leaving the two alone.

A moment of silence passed before Zundamon spoke again.

"Did Rei tell you how close we are? 'Cause we're soooo close. You wouldn' believe how close we are!"

"Yeah, she did." Defoko looked back at them.

They sat in silence.

*Ugh! He's not intimidated at all!*

Zundamon didn't realize they'd puffed out their cheeks.

"You're a...CeVIO, right?" Defoko asked.

"Yeah, why?"

"...Just wondering."

*Oh, is he wondering why I'm around an UTAU?! Is he gonna whine 'bout it like everyone back home?!*

Awkward silence settled between them in the same way Zundamon had done to the couple; Rei, of course, came back none the wiser, only pouring Zundamon some of her favorite peppermint tea.

"Thanks, sis." Zundamon didn't take their eyes off of Defoko.

"You are welcome, sister."

Defoko shifted again, then placed their arm across the back of the couch; Rei stared for a moment before reaching up and interlacing their hands and fingers, nearly giving Zundamon a heart attack.

Zundamon angrily bit down on the giant lollipop they'd been given by a shopkeeper; they were currently following Defoko and Rei as they perused the farmer's market in the UTAU worlds. Zundamon was usually excited for such an outing--but was struggling to hide their disappointment that Defoko was joining them.

"Sister, would you like to visit Gahata Meiji?" Rei asked. "I see that her stall is open today."

Zundamon perked up at that; Meiji was famous for her fortune telling and magical item stand. Zundamon knew someone who did something similar--Kafu, one of the few CeVIOs who was nice to them--but found that Meiji was more fun, as Kafu was far more serious about things whereas Meiji embraced the fantastical elements of their world and was more playful.

"Yeah!! I'll catch up to you guys!!"

Not waiting for a reply, they sprinted off, spotting Meiji's stand instantly and hurrying over.

"Meiji!!"

The hooded woman looked down and smiled upon seeing them.

"If it isn't my favorite customer!" She beamed. "Have a seat, Zundamon."

Zundamon hopped onto the stool in front of the counter; Meiji stood and moved closer.

"What would you like today? A taro reading? Perhaps one of my new items?"

"Crystal ball!!" Zundamon grinned. 

"Ohoho, I should have known."

Meiji set said ball onto the counter and removed its covering.

"What would you like to see?"

Zundamon thought for a long moment before replying.

"My sis just got a partner." They huffed. "Tell me if they're gonna break up soon!!"

Meiji blinked and seemed to resist a laugh.

"Alright. Let's see what the strings of fate have to offer..."

She closed her eyes, hands beginning to glow; the ball lit up, light beginning to swirl within. Zundamon leaned in close, watching as scenes began flashing by; Rei and Defoko's intertwined hands, them dancing together, and...

Wait.

Rei in a suit.

Defoko in a dress.

Oh no.

Meiji opened her eyes, the light and scenes fading away.

"It seems their fates are quite intertwined...only a few strands remain outside the fray."

Zundamon looked panic striken, nearly dropping their lollipop.

"...You're surprised." Meiji observed. "And frightened."

"Well yeah!!" They snapped. "They--they got--"

"Love is nothing to be frightened of, dear." Meiji hummed. 

"...D'ya love someone?"

"Mmm, there's someone." Meiji sighed wistfully. "But she's far out of my reach, now."

When Zundamon tilted their head, she continued.

"She was an UTAU like me, once." She looked down at her hands. "Renri. But she became a Synthv, and chose to move over to their worlds."

"...And you can't see each other anymore." Zundamon whispered.

"We can. We could. But...she's moved on. Onto greater things. She doesn't need me, anymore."

Zundamon swallowed hard.

"But that isn't always the case, dear. Sometimes love falls apart, but other times, it makes everything stronger."

*But not always.* Zundamon thought to themselves.

Rei and Defoko approached, calling for them; Zundamon reluctantly got up and bid Meiji goodbye, following their sister and her lover as they walked away.

Zundamon sat on the stairs, aggressively texting their group chat with Oliver, Rana, Una, Ritsu, Yuki, and Ryuto; most of the other kids insisted that no, they shouldn't break up their sister, but Zundamon wasn't having it, and demanded the others give them ideas on how to destroy the relationship.

They were distracted as someone knocked on the door; assuming it to be Defoko, they went over and yanked it open with a scowl.

"What do you want now--oh, hi, Teto."

They visibly relaxed as they let the redhead in; Teto smiled at them and sat on the couch.

"Hi, Zundamon. How've you been?"

"Been better." They grumbled. "Rei's upstairs, want me to get her?"

"Oh, I wanted to talk to you, actually."

"Huh?? Me??"

"Mhm! See, we're holding another music festival soon, and Miku and I wanted to perform No da. But we couldn't do that without our third singer, so..."

She smiled wide.

"We can help you with the dance we came up with! And if you need any help singing, we can do that, too."

Zundamon's eyes lit up.

"I get to sing on stage?!"

"If you're up for it--!"

"No duh I'm up for it!!"

She then sprinted up the stairs.

"Rei!! Rei, guess what!!"

Teto smiled as she stood up to go.

Zundamon growled as she watched Rei and Defoko from the bushes; the two were heading on a double date with Defoko's friends, Momo and Ruko. Zundamon had followed them, and was currently scheming on how to ruin everything.

Momo and Ruko approached, holding hands; they greeted their friends and entered the restaurant, Zundamon rushed in, diving under the usher's legs and slipping away before he could process what happened. They then spotted a waiter carrying an empty plate; they ran over, tripping them and grabbing the plate before launching it at Defoko--only for it to completely miss and crash into some other guy with long purple hair instead.

Zundamon panicked and dashed into the nearest set of plants; chaos was starting to ensue, as several waiters rushed to check on the man and beg him not to sue while others tried to figure out what exactly happened. Their next plan ended up being crawling through the plants--they looped all around the main room--and start throwing dirt; that also failed, the dirt not flying far enough, only landing on the floor and making the waiters slip.

Their next try was to slip into the kitchen and ruin the food--only to not even make it in, as an usher spotted them and picked them up before carrying them out of the restaurant. Thus, their plan was fully foiled.

Their next attempt was when Defoko was over for dinner.

Their eyes never left the purple menace, hoping that if they willed it, he would explode; sadly, that never happened. The backup plan was to make them uncomfortable, which went about as well as their first dance lesson with Miku and Teto.

"Purple reminds me of eggplants. Does purple smell as bad as they do?"

"It depends on the person."

*What kind of answer is that?!*

"You're a classic UTAU, right?"

"Yes."

"You're old!"

"I know."

Zundamon's cheeks puffed out without their knowledge; Rei was still none the wiser to her sister's antics being sarcasm or snide, thinking they were just having a conversation.

One day, Zundamon was leaving practice with Teto and Miku, only to find Defoko waiting for them outside the studio.

"What are you doin' here?!"

"Rei couldn't make it." He said. "She asked me to come get you."

"What?! Why not??"

"She fell and damaged her arm. She's getting it repaired."

"WHAT?! WHERE?!"

"Remain calm, please. She'll be fine. Momo is taking care of her."

He looked away.

"We can...go to see her together, if you want."

"Duh!! We gotta hurry!!"

Defoko nodded and began to lead the way; awkward silence sat between them until he spoke again.

"Rei told me you're going to perform at the next festival."

"Yeah, why?"

Defoko was quiet before speaking again.

"I don't like performing. But I admire those who can."

Zundamon blinked.

"Why not? Doesn't everyone like that stuff??"

He shook his head.

"Some people prefer behind the scenes stuff. Some people like to just watch. It varies."

"Weird. You just wanna watch?"

A nod.

"Huh..."

"I'm sure you'll do well." He looked away. 

"...Thanks, Old Purple."

When he looked at them with a raised brow, they shrugged.

"You're old an' purple."

"...I guess that makes sense, then."

They fell into silence for a bit.

"...Why are you with my sister?"

Crap. They hadn't meant to blurt that out, at least not loud enough for him to hear. But he did, and looked down at them.

"I like her. A lot."

"Yeah, but..."

They bit their lower lip.

"You're...worried, aren't you?" Defoko asked, quietly.

"No..."

A pregnant pause.

"There's no need." Defoko offered. "I...don't want to replace anyone."

Replace. A replacement.

Discarding.

Alone.

Forgotten.

Zundamon didn't realize they'd stopped in their tracks.

"Shut up..."

"I...I've been nervous, too. Getting to know--"

"SHUT UP!!"

They didn't notice the tears stinging their eyes. 

"You don't wanna replace me?! Then DON'T COME BACK!!"

They spun around and sprinted away, not knowing where exactly they were going.

"That sucks...I'm sorry..."

Zundamon had found themselves at Ryuto's place; after pounding on the door, he'd eventually let them in, and they had dumped everything onto him--how they'd been feeling, their anger, the talk with Defoko, etc. 

He frowned, reaching out and patting their hand.

"Maybe you could talk to Rei?"

"Huh??"

"I talk to Gumi when I'm upset. It helps."

"But--but then she'll get frustrated and leave, and--"

They started to tear up again.

"I don't wanna be alone again..."

His frown deepened.

"Why would she get upset??"

"Cause--everyone back home thinks I'm some annoying kid. Or just annoying. Maybe she'll start thinkin' that, too."

"But it's been a year!!" He reached out and grabbed her hand. "Wouldn't she have stopped being your sister by now if she thought that? Or not taken you in at all??"

"M...Maybe..."

A knock at the door distracted them; Ryuto looked down at their held hands and blushed, but Zundamon didn't notice as she pulled away. When they opened the door, they found Rei and Defoko; before they could say anything, Rei kneeled and wrapped her arms around Zundamon.

"Sister. I have learned that you are...upset."

Zundamon tensed up.

"Let us...speak about this, privately."

She pulled away and grabbed their hand, walking away; surprisingly, Defoko didn't follow. They looked over their shoulder to see Ryuto giving an encouraging smile.

Zundamon tilted their head as they walked down the street; it was the street they'd first met Rei on, over a year ago.

"Sister."

Zundamon looked up; Rei had spoken for the first time since they'd started walking.

"Do you...remember this place?"

"Duh, of course!" Zundamon sounded exasperated. "How could I forget...?"

Rei only nodded before continuing.

"I would never forget, either. I come here, sometimes, because I...am glad."

*Huh...?*

"I am glad that I went out that day." She said. "I am glad you begged me to become your sister."

"I-I didn' beg!!"

"By definition, you did."

They grumbled as she continued.

"I am...happy. Defoko, makes me so. But...I am also happy when I am with you."

She looked up at the endless sky.

"I am not designed to be a sister. But...I am glad to be one."

Zundamon stared, starting to tear up again.

"You will never be replaced. I will...make sure of that."

She looked down at them again.

"Perhaps we can all be...a family, of sorts. Despite our designs."

Zundamon swallowed hard; they were nervous. But...Rei's reassurance hit them hard, hit them right in the heart. They reached out for a hug, which Rei gave to them.

"Maybe." Zundamon sniffled. "But...baby steps, please?"

"I understand, sister."

Zundamon took a deep breath; Miku and Teto had just finished Mesmerizer, and were announcing to the audience that their next song had a special third singer. When Zundamon entered the stage to thunderous applause, they looked around--and spotted Rei and Defoko in the front row.

A smile plastered itself on their face at the sight; maybe, just maybe, they'd be okay.