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The Past we Can't Forget

Summary:

A long time ago, Four created a new world in their head out of boredom. Earth. Little did they know, that world would evolve into something much more than the tiny little project it began as.
After the Zero's kicked Four out of their group, Four decided to pass time by visiting some of their old creations. When they came across an old world they had long forgotten about, they begun exploring what the world had came to over the years they left it alone. They started spending more time in the new planet than in the playground, making themselves a whole life there, with friends, family, and even school. But what happens when the two universes start colliding? What happens when problems start piling up in both worlds? What happens when they lose control of their own creation?
Four knows they can fix it.
They can make everyone happy again.
They can bring everyone together.
Forever.

 

This fic is inspired by (Or an AU of) Integers of Another Understanding by Swis_Cheez. It's not required to read it before reading this one, but it is a good fic that I would recommend!

Notes:

Heya! This is my first fic so please bare with me :,)
This story is made by me and my friend Rotten Apple, so we both helped make the plot! (Although, I, Candy Apple, am the only one writing out the story so far until further notice) Rotten is also making a book of character designs (It'll be posted on the same account that this story is published on) so make sure to check that out too!
This story is meant to be a little confusing at first, and most mysteries will be solved later on! My posting schedule will be ranging from 2 days to a week.
Also!! Make sure to read the tags carefully because I will not be adding trigger warnings in the chapter notes to avoid spoiling the chapter. (Unless anyone specifically asks me to do so)
hope this is good, I don't know how to do this.

Edit (1/18/26): warning, this book is like the bad first season to this series. If the writing is bad.... no it isn't you didn't see anything...
I might revamp the beginning chapters more sometime... please bare with me it gets better I swear

Edit (3/31/26) Also, to avoid spoilers in the tags, things that have to do with major events will be marked with tags relating to them but not explicitly stating the major event. For example, if a tag said, "heavy violence" there might be a murder or something like that.

Chapter 1: Time Flies

Chapter Text

It had been quite some time since Four last visited the playground.


Recently, they were spending so much of their time in their new world that the playground felt like a fever dream whenever they thought about it. The only reason they came back to the Arithmetic World nowadays was to keep their dear friend company. Zara was one of the only zero’s who they talked to, all of the others leaving them after they had merged with the number four. They always wondered why they had been left in the dust by the Zeros. Them and the others were pretty close until they merged themself with an integer after all. They were alone now, and it was  all because of a stupid dare. Ever since then, Zara had been the only one to talk to them, and even with her help, it was a little too lonely in the Arithmetic Realm. In remedy of this, they found themselves retreating to one of the old worlds in their head they had created years ago. They found the world had evolved so much since they last visited, it was totally different then how they intended it to be! Four wondered if their new world could be considered their home now. They spent more time there than here as of late. 

Four sighed. This was a subject for another day. They should focus on finding Zara. Glancing around, they spotted the shorter number in their peripheral vision. 

“Zara!” They greeted her. This caught the grey haired girl’s attention, her spinning around to greet Four.

“Hey Finn!” She greeted back, using that weird nickname she had come up with for them. They always wondered how she came up with it. It was a weird coincidence that it was the same name they used when they were in their other worlds. 

“How's it like in your new place?” Zara continued. Four guessed she was referring to the second world. 

Four hummed. “Fine,” They stated.

“Something on your mind?” Zara inquired.

There was a lot on their mind. How did Zara always know when something was bothering them? How did having two different worlds they made in their head affect the correlation between time and space? Why didn’t Zara seem to miss them after they traveled to the other world for weeks? They thought they’d been gone for a while! They landed on that thought, stopping to think about it for a moment. They knew it was stuck up to want Zara to miss them, and they knew that if they thought she would miss them, then they should’ve come back sooner. To not act so selfishly, Four decided against telling Zara the thoughts weighing them down the most. Instead, they could settle for something much simpler. 

“Well, I was just thinking about your, uhh,” they paused. "Your clothes. How do you know what to wear everyday?" It was a good enough excuse. She didn't have a reason to object, and she was quite into fashion, so it'd surely be something that would peak her interest. 

“Oh! Well, sometimes I look at the other zeros for ideas, but you know them..." She shook her head. "Oh, I get some of my ideas from books! Like this skirt, one of the characters in a book I was reading wore it! Cute, huh?" 

"Yeah, that's cool."

Zara nodded, a bright smile now plastered onto her face. The two of them stood in silence for a couple of minutes. Awkward silence, or at least that's what Four would call it. The blue haired integer was getting bored of this world, and figured it would be much more entertaining to be on Earth. Zara didn’t seem to miss them last time they went to the other world, so maybe she wouldn’t miss them if they just went there right now! Although, the question still remained. Why hadn’t she missed them? She was acting like they weren’t even gone for that long. They were in the other world for weeks! Or maybe time passed differently on Earth than it did here. That would be interesting. Maybe they should go back to the other world just to test it out. No other reasons! Yeah, yeah, that sounded like a good idea to them. It’s not like they would be gone for very long.

 

—----

 

Finn’s eyes fluttered open. They heard their sibling, Tobi, calling their name. Tobias had been trying to wake their sibling for the past ten minutes, but all their attempts had ended in vain. Finn’s had always been a very deep sleeper, sometimes even falling asleep with their eyes open. It was quite annoying.

“It’s been ten minutes! You have to get up, or we’ll miss the bus,” Tobi complained.

Their ever so slightly younger sibling responded with a grunt, rolling off of their bed with a thud. They got up lazily, stumbling and almost falling over again. Tobi chuckled, much to Finn's distaste. 

Finnlee tried their best to find an outfit, sorting through their clothes, not putting much thought into what it was. Tobi couldn’t help but grimace at the outfit their sibling had picked out. The clothes were wrinkled and it was obviously not very thought out. They thought about telling Finn about how the color of their shirt completely threw off their blue hair, but they figured there was no time for delay. Finn however, did not have the same mindset as them, their movements indicating no rush as they walked as slowly as they possibly could to the bathroom. Of course, they didn’t want to be late. Not necessarily. They wanted to delay going to school, not be late to it. Unlike the popular belief among their friends and family, Finnlee despised school. Sure, they were good at it, but that didn’t mean they liked the wretched place. Them delaying going to school was a common occurrence, much to their older sibling’s annoyance. 

They opened the drawer in their bathroom with a squeak, messing around with a couple of items before finding their mint toothpaste hidden all the way in the back. They liked mint flavored things, but Tobi was quite the opposite. When their parents first made the two siblings try mint toothpaste, Tobi whined like a baby at the fact that they had to sacrifice their “sparkly bubblegum” flavored toothpaste for the “boring adult one”. Finn chuckled at the memory. They never knew why Tobi made such a big fuss about it. Tobi still hated the flavor to this day, to Finn’s amusement.

“The bus leaves in 8 minutes!” Tobi yelled from downstairs, catching Finn’s attention. To Tobi’s surprise, they rushed down the stairs quickly.

“What’s gotten into you?” Tobi teased. Finn never made too much of an effort to get to school on time, and it seemed today was one of the rare exceptions.

Finn scoffed. “We have a math test today. Don’t tell me you forgot,” Finn reminded them. 

The words “math test” hit Tobi like a bullet. They had completely forgotten to study, and their grade was nearing a C. Finn smirked at their older sibling’s shocked expression. They looked like the life had been taken out of them. They stared at their un-moving sibling for at least another 5 seconds before nudging  them. And Tobi was the one who told them to hurry up. Gosh, hypocritical much?

 Their nudge seemed to have woken Tobi out of their 5 second trance, them continuing to tie their shoes. The two rushed out the door and down the block just in time to catch the bus. After filing in through the slim doorway, they made their way to their usual seat, next to their friend Xylin. 

“Morning!” Xylin greeted cheerfully. 

Tobi waved and smiled, while Finnlee greeted them back.

“You guys almost missed the bus!” Xy informed, making a motion with their hand to emphasize their claim. 

“Yeah, thanks to somebody,” Tobi blamed, glaring at Finnlee.

Finn rolled their eyes in response. The group sat in silence for a minute or so, the absence of sound allowing Finnlee to listen in on the conversation being held behind them, where two girls were bickering about whether drama or musical theater was the better pick in course selection. That reminded them, they had no clue what to choose for their 12th grade elective. People had started submitting their course selection papers, and they didn’t want to miss the deadline. 

“Say, guys, what are you choosing for your elective next year?” Finn asked the group.  

“I’m gonna take Spanish three,” Xylin shared.

“What about you Tobi?” Finn inquired. 

“Oh, I'm doing Spanish three as well,” They answered.

Finn hummed in response. Another wave of silence passed by the group. 

“Say, what do you think Olivia is taking?” Tobi asked.

Finnlee chuckled. “Why, want to be with your girlfriend?” They teased.

Tobi scoffed. “No, I'm just curious! As I said before, we’re just friends.”

 Finnlee rolled their eyes. It was painfully obvious that Tobi liked Olivia, but they would never admit to it no matter how much Finn pried. Never had the guts to ask her out either. It was kind of sad to watch.

“To answer your question, she told me she was taking Mandarin three,” They answered. 

The disappointment showed on Tobi’s face a little more than they would’ve liked it to. Xylin and Finnlee glanced at each other, Finn rolling their eyes and Xylin snickering.

“You two cannot be talking, you obviously like each other!” Tobi defended themselves.

“Come on, don’t make this about us!” Xylin protested. 

“Yeah, don’t avoid the allegations, Tobias Syndrastone,” Finn mocked their sibling. When they got the hint that Tobi wasn’t going to respond, they rolled their eyes again, overplaying their annoyance. They turn their attention to the kids sitting across from them. They looked younger, like freshmen, and were bickering about some meme on one of their phones. The younger boys reminded Finnlee of how their friends Nike and Sylvia were when they first met. Not long after Finnlee was adopted into Tobi’s family, they had been sat next to Sylvia in class. They didn’t really talk much at first, but Nike would go to their table and constantly pester them and Sylvia. Now that they thought about it, they didn’t really remember how the three of them became friends, but they assumed Nike bothered them so much that they all formed some sort of bond over it.

The bus rolled to a stop, and kids began to pile out of the exit. Finnlee and Tobias then split up with Xylin and said their goodbyes, before beginning to walk to their first period, math. Math was Finn’s favorite period, it came really easy for them. Easy in their opinion at least. They knew Tobi would strongly disagree. They had always struggled with mathematics, and made Finn do their math work in exchange for them doing Tobi’s history homework. Finn didn’t particularly struggle with history, but it was really boring to learn about ancient Britain or how society developed. They would much rather be doing math than history any day of the week. 

Eventually, the Finnlee made their way into the classroom behind Tobi, who had the same math class as them. They took a moment to jog their memory before remembering where their seat was, quickly moving towards the other side of the classroom to sit in their oddly wobbly chair. Once seated, they opened up their chromebook to work on the slideshow their teacher had assigned the other day, nudging Tobi, who sat next to them, to do the same. The two siblings had been working on the slideshow together, as it was a group project, and Finnlee didn’t know many others in the class. Even if it meant doing most of the project by themselves due to Tobi’s deteriorating math skills, Tobi was better than some random person they barely knew. Maybe. They sighed. 

Their train of thought stopped when their teacher started to walk towards the center of the room.

“Good morning everyone,” their teacher, Mr. Bryce, greeted. 

“Good morning Mr, Bryce!” Exclaimed one student, who was always energetic and greatly extroverted. Finnlee would never understand how someone can have that much energy at eight in the morning. They tried not to listen as their classmate talked more, (very loudly so) and tried their best to focus on their project. They could tell this was going to be a long day.

 

-------

 

It had certainly been a long day. From their essay in ELA to their extra laps in PE, Finn’s energy was as drained as ever. Finally back at their house, they figured it was about time to take a break from drawing and go back to the Arithmetic World to talk to Zara, but even though they knew it was the right thing to do, they were way too sleepy to have a conversation with her right now. Plus, if their time passage theory was true, spending too long in the other world could make it look like they were asleep for days on earth. Of course, they loved visiting Zara, but they were just too tired right now. 

The bathroom door creaked open, revealing their sibling behind it.

“What’s cooking?” Tobi greeted, the use of slang sounding odd due to their British accent. 

“Since when do you say what’s cooking?” Finn retorted. 

“Since now!” Their sibling bickered back. 

Finnlee rolled their eyes at them for what felt like the 50th time today, before turning their attention back to their drawing. They were drawing themselves in the other universe. Four. They finished sketching their head and face, making their way into the hair after around a minute or so. In the Arithmetic realm, they had blue hair, longer than it was on earth, and strange stubs poking out of their head. They drew them in, and then added their Four hairclip and T-shirt. They topped it off with their glasses, finishing the sketch. They leaned back in their chair, looking at their drawing from afar to try and notice any errors.

“What’cha drawing?” Tobi asked.

“Just my character. Same one as always,” They answered, beginning to start shading the hair.

Tobi got up from their chair to take a look.

“Oh, cool!” They complimented. 

“Thanks,” They reciprocated. 

They began coloring their work, praying they wouldn’t mess it up. The markers made a scratching noise when they hit the paper. A noise that hurt Finn’s ears. It was probably bothering Tobi too, the older sibling leaving the room. Finn assumed they were beginning to make dinner, since they usually did around this time. Sometimes they felt guilty for not being able to help with the meals, but it wasn’t their fault their parents never taught them how to cook properly and the stoves were weird on Earth. It would be easier if their parents were home more often, so they could just have them make the dinners like Xylin’s mom did, but they knew their parents were too busy with work. That reminded them, weren’t they taking a couple days off for spring break? The corners of their mouth turned upwards at the thought. Even if their parents weren’t the nicest, Finn always appreciated it when they took a break from work. It was nice to see them. Finn’s gaze focused outside, noticing it was getting darker. They had been drawing for a while. Maybe it was time for a break.

Finnlee opened their phone, deciding to text Xylin. Their blond friend responded quickly, with their usual “Hey!” followed by their favorite emoji. The two of them talked for a bit about various subjects ranging from their favorite foods to the meaning of life. Finn had always liked talking to them. It served as a break from the world. Whenever they were around them, Xy would always make them feel like their problems went away, like the weight of the world had been lifted. They didn’t know how Xylin had that effect, but they hoped they could do that to them too. They didn’t know what they would do without them.

“Finn!” Tobi called out, interrupting the blue hair’s thoughts. “Dinner!” They continued.

Finn sent a quick goodbye text to Xylin before rushing downstairs to eat. They sat in their seat, looking out the big window in front of them. There was little to no light outside anymore. The day had passed. Time flies, they thought. Life is so short. It could end any moment now, their thoughts continued, darkening. A frown formed on their face, as they tried to brush past it. None of that mattered right now, they didn’t want to ruin their mood.

Hopefully tomorrow, they would feel better.

Things can only go up from here, right?