Timelines (A Doctor Who/Undertale crossover)

Chapter 16

Once they got started, progress on the machine went very fast. Sans had uncovered some extra blueprint models in a small corner of the lab and modified them to suit whatever purpose the machine required. The Doctor had taken it upon himself to use the "TARDIS" as machine parts, and it was not uncommon to hear the sounds of electronic buzzing constantly throughout the day. Frisk, knowing next to nothing about machines and space and time, used their time to help Papyrus cook snacks for the other two. It was usually just spaghetti, but occasionally they would throw in some half-burnt brownies or something.

One day, as they were just finishing up the progress of the monitor of the machine, they began to get some strange readings.

"uh, guys? you might wanna see this,"

Frisk and the Doctor rushed over to Sans, who was staring intently at the screen of the monitor. On it was a complete map of the underground with hundreds of red dots. At periodic intervals, a dot would blink slightly, then vanish.

"What's going on?" Frisk asked, not really making much sense out of the map.

"this is a map of the entire underground," Sans replied in explanation, "each of these red dots represent a specific monster in the underground. look," he pointed at a large group of monsters in Snowdin, "there's grillby's bar. and over here, those three dots are us."

Frisk nodded and glanced at the Ruins. No more dots were present there. "What happens when a dot goes missing?"

"it has to have something to do with the cracks," Sans pointed at Temmie Village, "there are no temmies here, so it has to be something like that."

"So if someone disappears, what happens to them?" The Doctor asked.

"actually, i've been thinking about that. have you guys tried mentioning the temmies to anyone yet?"

They shook their heads.

"it won't do anything. nobody even remembers they existed. for some reason, the void seems to be "eating" these monsters and leaving no trace of their existence."

"So how come we remember?" Frisk asked.

"i think it's because we're all too familiar with space and time. doc, you constantly travel around in your space-machine, frisk, well yours is obvious. and i've got my teleportation abilities."

"How do we get the erased monsters back?" The Doctor asked. Sans shrugged.

"i haven't gotten that far yet. we're gonna need a lot more information."

So with that, work on a second machine began. This machine would monitor the cracks specifically and try to figure out what exactly happened to the lost monsters. As Sans worked on this machine, the Doctor began another one to monitor the timelines.

Things seemed to actually be working well for once. Their progress was going quickly with only mild setbacks and limitations. The Doctor's fixed sonic screwdriver also helped, considering he could do almost anything with it. One day, just after Sans had announced that work on the second machine had been completed, something strange happened. A small crack, no more than a centimeter in length, had appeared on the floor next to one of the monitors. Frisk was the first one to notice this, and immediately brought it to the others' attention.

"There starting to come here," Frisk said, gesturing to the crack, "Do you think more will appear?"

"Hopefully not," The Doctor replied, crouching down to the crack and running his finger along it, "We can't afford to lose all this progress."

"and if more do appear?" Sans asked. The Doctor shrugged.

"I'm not sure. Let's continue working, but keep our eyes on it."

Over the next few days, the crack only grew wider and wider, making the three of them more and more nervous. Not only that, it had begun to branch out and create a sort of broken glass pattern on the floor. Everyone's walks across the room had turned into very intense rounds of hopscotch as they tried their best to avoid them. It was only a matter of time before something horrible happened.

The Doctor had just finished programming one of the machines with his sonic when there was a large tremor in the ground. Everyone looked around to find the cause of it, when another came and the cracks in the floor grew larger. Another quake made then even larger. The Doctor walked over to the cracks and bent down to inspect them. After a few moments of silence, he spoke.

"Run."

"What?"

"Run. Run!!! Out of the lab! Now!"

He didn't have to tell them twice. Together, all three of them rushed out of the lab and were met with a horrible sight. The cracks in Snowdin town were growing to outrageous proportions. Several buildings had already collapsed and more were on their way. A group of monsters was gathered around one of the larger rifts and seemed to be arguing. The Doctor didn't waste a breath before running over to them. He pushed through the crowd to a tall monster who was holding his hand towards the crack.

"Whatever you're doing, stop it now!" The Doctor shouted at him. The monster glanced back at him with a smirk on his face.

"And why should I listen to you?"

The Doctor huffed in frustration. He didn't have time to argue with people. He needed to get them out of the town. Another quake shook the ground beneath them, causing the cracks to jump open about a foot in width. The monster turned his attention back to the crack.

"I'll prove it's harmless, Jim!" He said to another monster in the crowd. "Watch me."

"Listen to me!" The Doctor yelled in frustration, "If you value your life. Your family, your accomplishments, your very existence! Everything you've ever done or ever will do, then please, step away from that thing right now." He held out a hand to the monster, who's smile faltered. The monster glanced back at the crack and took a step away.

At that moment, another huge shake happened, this time accompanied with the loud screams of the monster. Everyone watched as the crack split the earth underneath him and he fell right into it. Within less than a second, he was gone. Consumed by the void. The rest of the monsters looked around cluelessly, confused as to why they were staring so intently at the crack in the ground in front of them. The Doctor stared silently at it for a few moments before another shake brought his attention back to the rest of them.

"Everyone!" He shouted at the crowd, "Get out of the town! Hurry!"

This successfully managed to grab their attention. Everyone dashed towards the entrance to Waterfall, trying their best to avoid the cracks now growing incredibly fast in the ground. Occasionally the sound of screams filled the air as unfortunate monsters lost their footing and were lost to the void. Finally, the Doctor, Sans, and Frisk managed to get the remaining members of the town safely into Waterfall just in time to see the last remaining pieces of Snowdin be consumed by the void.

"It's all gone," Frisk said quietly, "Everything. The town, the Ruins, our progress, everything."

Nobody responded. Sans was too busy hugging his brother, grateful that they had both managed to escape. The Doctor merely stared out into the void with a stone-faced expression. The rest of the locals were standing still in confusion and horror. Nobody was expecting anything like that to happen, and now they were all faced with the question of if it will happen again.