Sans, you quickly learn, knows how to work hard. Of the five of you there, he works the most, the hardest, the longest. It's... a little scary, to be honest. Sans has almost as much determination as Flowey, you think, who has almost as much determination as you. Sans, you realize, can probably find a way to do anything he sets his mind to, so long as you're not opposing him with all your own determination.
But working together... you're unstoppable.
And you're making progress. Sans goes over the blueprints Alphys had been working on, and makes some modifications to his own. You help him and pick up a ton of supplies. In a matter of days, thanks to Papyrus and Undyne, Sans' partially-built machine looks more like an actual in-progress project, rather than a long-since abandoned construction site. And Alphys and Sans get the CORE turned on again (it was shut down when the Underground was abandoned) and Sans apparently knows how the CORE was built, and has a few tricks to peak the efficiency.
And over the next few weeks, you, Alphys, and Undyne practically move into Sans and Papyrus's house. It takes both Sans and Papyrus to convince Toriel it's okay that you're staying there. Once she accepts that, she still stops by often to check on you.
"hey, this is good for them." You overhear Sans arguing once on your behalf. "it's like... i dunno. a summer camp or something. and it's good for them to work on something big. it 'builds character' or something like that." Then he shrugs. "at any rate, it'll give the kid something interesting to say they did over summer vacation when they go back to school."
School. It's like the deadline of all deadlines. With it already mid-July, you've only a month and a half to get this done before school starts in September. Because you know Toriel definitely won't allow you to stay at Sans and Papyrus's during the school week. You don't know how you'll manage to help Sans with this once school starts.
You resolve to do your best. You resolve to stay determined.
Then, one day, Sans pulls you aside. "kiddo, lookit this." He leads you over to a computer monitor. The majority of the screen is black. At the bottom are a bunch of data values that make no sense to you. Onscreen, though, there's a single white vertical line. There's a small marker in the middle.
"see this?" Sans asks. "what do you think it is?"
You just shrug a little. You have no idea.
"well, alright, when was the last time you saved?"
"This morning." You usually save every morning, just in case something happens. It's pretty nice and convenient that there's a SAVE point right outside your house, and another outside the brothers' house. (You have pondered that before, why there are always SAVE points in convenient locations, but no answer has ever come to mind.)
Sans nods a little. "okay, reset to then."
You frown a little. "Why?"
Sans just gives you a wink. "i wanna show you something cool."
You shrug a little, and reach for your LOAD SAVE FILE button.
And then you're outside the brothers' house again, back to when you saved that morning. This morning. Whatever.
When you walk into the basement, Sans is already there. He grins at you. "'bout time you showed up."
You laugh a little. And then you see the computer monitor in front of him. It's like the white line has been cut off, looped around, spliced unto itself, and continued. So now there are two lines.
"i'm guessin' i told ya to reset?" Sans chuckles a little. "this is what it does."
"It's the timelines." You murmur.
Sans nods, and points to the timeline with the loop and the splice. You notice that's the line the marker is on. "that's us. and, i guess the other line is one where you didn't reset."
You look at Sans. Then you look back at the monitor. Then you look at Sans again.
The hope is still there, shining in his eyesockets.
It fills you with determination.
And then...
A few days later, Sans says you have one part of the machine built, and you're ready to test it.
You ask him if he's nervous.
"nah. not yet. see, kid, a lot of this stuff i've done before, the other time." That's how he refers to anything that has to do with the Royal Scientist. The 'other time', or the 'last time', or sometimes even the 'time before'. "stuff like this bit? folding space? i know we can do it because i've done it before. i won't be nervous until we get to the point where things went wrong last time."
You suppose that makes sense.
So you watch. Sans has a small device that he says will be put through the fold, just to test it. You don't really understand how something can go 'through' a fold, but Sans says it'll work. You trust him.
And it does work. It's like there's a distortion in the air. Alphys is at the control panel of the machine, and Sans is the one who's dropping the camera into the fold. You wanted to drop it in, but he says it's safer if he does, because he knows what to do if he falls in. That just makes you wonder how he knows.
But everything goes smoothly. Sans drops the device, it's like you blink, and the camera is landing on the opposite end of the room.
Sans just grins amid everyone's cheers. Yeah, he knew it would work. He definitely did.
Nonetheless, as he watches you, Undyne, Alphys, and Papyrus excitedly shouting over the success, you can't help but notice how happy Sans looks.
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A/N
Y'know what I really love about writing from Frisk's perspective? I can say there's a bunch of complicated science-y stuff, and not have to come up with a plausible-sounding explanation for it because Frisk wouldn't understand it.
Anyway, thanks for reading, and I hope you enjoyed it! Comments and votes are my Favorite Things, and every notification I get makes my day!