Chapter Text
It was the next day.
Undyne had knocked on the skeleton brothers' door after Stretch called her over. It was almost a miracle that Alphys hadn't come with her.
But this would be about science stuff, and Alphys got bored pretty fast by such "ass-complicated shit", how she tended to put it.
Stretch let her in and showed her to Blue's room.
Before he entered he knocked gently and announced his and Undyne's presence.
When they entered, there were AD and Blue, sitting next to the nest and drawing with crayons, together with Red.
They'd gotten him the crayons the day before and AD had explained to him how to use them and that there was nothing he could do wrong with them, as long as he wouldn't draw on things that were hard to clean, like the wallpaper. The best thing to draw on was paper, after all.
At first Red had been very unsure in using the crayons and in his choice of color, especially since he didn't know many colors. But AD had told him the names of the colors and Red, despite being unsure of himself, got them right most of the time whenever AD asked him once in a while if he remembered the color.
That only confirmed AD's suspicion that the small skeleton was way smarter than he thought of himself.
After experimenting a little with how to hold them correctly and what would happen when he drew over one color with another, Red began to try shapes like shaky circles or letters he had seen Other Master scribble down, even if Red didn't know what they meant.
Then he began drawing from memory. Of course it was childlike doodles, but still recognizable.
When Undyne sat down next to Stretch and just watched Red doodling for a moment, she could make out an echo flower, something that looked like Nice Cream Pants, but with the Burger Guy's food cart next to him, a Flowey and some kind of fierce looking beast that Undyne couldn't place.
Meh, she could ask about it when they had chewed through the subject she came here for. Stretch had a theory about where Red had come from, but he hadn't said more on the phone.
She looked at Blue. "H-hi, how had he b-been doing?"
"Better," Blue beamed. "Of course he's still afraid of strangers, but he really seems to open up around AD and me. Sadly he's still nervous and sometimes even skittish around Pap."
Stretch just shrugged. "Eh, when my theory is right, it's no wonder. It is kinda sad, but i can't blame him. I hope he'll come around over time.
AD wrote down what Red told him about how he got here. And... to not drag it out longer than necessary, i think, Red is Sans from another universe."
Everyone, except Red who was still drawing, stared at Stretch, speechless.
"You mean like... a parallel universe? Like in some of those movies from the surface?" AD asked.
Stretch nodded. "Exactly. Could you read to us, what Red told you? Just to make sure that we all heard it from the same source at least once."
AD just shrugged and pulled his notebook from his inventory, flipping through the pages until he found the right one. He read it aloud while his free paw pet Red's head.
The red skeleton paid the conversation no attention, instead he snuggled closer to AD and leaned into the nice touch while keeping on drawing and unconsciously started purring.
---
"S-so, p-putting everything together, it seems l-logic," Undyne finally said. Like always when her mind was occupied with something scientific interesting, her stutter disappeared completely as soon as her thoughts gained momentum.
"The layout of his former 'home', the skeleton that looked so much like Papyrus, the 'dark and wet place' that has to be Waterfall, how he described the surroundings of the other house, and finally, the portal, that, apparently, had brought Red here. Did i forget something?" She looked at the others.
None of them could think of anything. Not right from the top of their heads.
"He... really is another me?" Blue inquired. "And his Papyrus did all those awful things to him. But who is this other guy? The scientist?"
Stretch longed for a cigarette now, but just produced a sucker. "If i'm correct, it's someone who was pretty important to our Underground too, but here something happened and nobody remembers him anymore."
AD tilted his head. "Who? And... how?"
Papyrus took a slow deep breath as if inhaling the smoke of a cigarette. "I don't know why, but i never met anyone who remembers ever hearing the name 'W. D. Gaster'. The royal scientist who once built the Core and studied Souls in order to get us back to the surface. One day he had an accident while doing an experiment with the Core. He and his personal assistant, River, who tried to help him, fell in.
Somehow the concentrated Magic of the Core fused them into one being, before they could get out.
After that, they experienced total amnesia and became the monster we now know as the Riverperson. For everyone else in the Underground it was as if neither Gaster nor River ever existed. There's only the Riverperson. And no one seems ever to wonder, who built the Core.
Gaster was also our father. Kind of. He used his own Soul and Magic to create us, first me, and when i got lonely since i had no one to play with, he made Sans. He was too young to remember that time.
Since the Riverperson didn't remember ever being our father, there was no sense in staying with them. Luckily Muffet found us when she decided to move to Snowdin, and took us in.
Long story short, and personal stories aside, that other skeleton must be Gaster. Red's version of him, that is."
"Do you think that other Gaster made Red and his Papyrus like ours did?" Blue asked. "If so, why would he treat them so differently?"
"Maybe," AD began slowly, "it's because Red is so small. Or he created both for different reasons. A lot in Red's world differs from ours, so why not Gaster's reasoning for his creating Red and the other Papyrus and treating them like he did? And don't forget that we don't know for sure if Red and the other are even brothers or created artificially."
"A-as long as we c-can't get to a-a-ask Red's version of Gaster and P-papyrus, we will n-never kn-kn-know for ssshhhh-ure. Until we m-might get a chance a-at that, w-we should focus o-on R-red," Undyne decided.
The others nodded. Undyne was right. As long as they couldn't reach Red's world, what sounded like a dangerous and horrible idea in itself, there was no point in thinking about it. But Red was here. And he needed them.