Timelines (A Doctor Who/Undertale crossover)

Chapter 15

"This would be a whole lot easier if you'd just cooperate, you know."

The Doctor was walking through the snow just in front of Sans and Papyrus' house. He had his sonic screwdriver pointed in the air and was talking to it with a great amount of exasperation in his voice. The tip flickered and made different noises, which apparently didn't make much sense to him. He hit it a couple times on his palm, but it didn't help much. Before he could do anything else, he spotted Frisk running into town.

"Frisk?" He said in confusion, "What are you doing here?"

Frisk didn't respond and instead grabbed his sleeve and pulled him towards the house. "Sans figured it out."

"Figured what out?"

"I don't know yet," They rounded a corner to the back of the house and were faced with a gray door. "But we're about to find out."

The Doctor stared at the door for a moment before pushing his hand against it. "Locked. Hold on a moment," he pointed the sonic screwdriver at the lock and it clicked open. They pushed open the door and stepped inside.

"'bout time you got here,"

Sans was sitting on the floor in the middle of  what looked like a small laboratory. He was writing something down on a piece of paper and didn't even look up to acknowledge them. The walls of the lab were gray and a large tarp covered something in the corner. There was also a large display case on the wall filled with blueprints for a machine of some sort. The floor around Sans was covered in books about quantum physics and papers with illegible notes scribbled on them. After Frisk and the Doctor had stared in awe around the room, Frisk walked up to Sans.

"So what did you figure out?" Frisk asked as the Doctor began to explore the room.

"i think i might have figured out what the cracks are," sans said, "you know how i can teleport and stuff like that? well when doing so i travel through the void, a place where space and time are nonexistent. if we can build a machine of some sort to monitor this, we might be able to find a way to stop it."

Frisk grinned. "That's perfect!"

Sans nodded, but before he could speak there was a voice from the other side of the room.

"What language is this?" The Doctor asked Sans, pointing at the blueprints in the display case. They were written in many strange symbols which made no apparent sense. Sans looked up.

"eh. it's a dead one. nobody knows how to speak it and i don't even remember what it's called," He responded.

"That's not possible," the Doctor retorted indignantly, "The TARDIS makes it so that anyone who is in it can understand any and every language in the universe. That," he pointed at the prints, "isn't supposed to happen."

Sans shrugged. "i dunno, doc. i guess it's broken. don't worry, i'm sure you'll be able to doctor it up."

The Doctor was about to reply, but stopped once he realized what Sans had said. "Was that a pun?"

Sans merely shrugged. Frisk stood next to him giggling.

"That was horrible," The Doctor said, trying to fight back a smile.

"hey, my puns might not be that great, but at least i'm giving them a shot."

Friends giggling grew louder. The Doctor sighed. "I'm not that kind of doctor," he said in exasperation.

"i dunno. even if you aren't, at least the humor is leaving frisk in stitches."

Frisk laughed even harder, causing the Doctor to break a slight smile. He turned away from them for a moment to let Frisk calm down. Once the silence in the room had resumed once again, he decided to speak up.

"What's this?" He asked, gesturing to the tarp-covered mound in the corner. Sans stiffened.

"nothing," he said shortly. The Doctor raised an eyebrow.

"Really?" He said pacing around, "I think that throughout my entire life I've had people lie to me. I've learned when somebody is telling a lie and that," he grinned, "was most definitely one."

With that, he grabbed the tarp. Sans tried to stand up and stop him, but was too late. The tarp was pulled off to reveal a tall, cylindrical object. The Doctor's eyes widened.

"What is that?" Frisk asked.

"It's a TARDIS,"

"A TARDIS? Like your time machine?"

"Yes," he said, running a hand along the side, "but this one's different." His hand latched onto a door handle which he pulled open. The inside was a complete mess of wires and metal and seemed to be a complete disaster.

"Where did you get this?" The Doctor asked Sans who shrugged.

"a friend of mine was working on it before he left," he said simply. Frisk knitted their eyebrows at him in confusion, but the Doctor didn't notice.

"Well the thing is he made a crucial error. You can't just build a TARDIS. It doesn't work that way. Physics, I mean. A TARDIS is bigger on the inside because it is a complete pocket dimension. You can't just stuff a full reality into a small box, so instead you have to grow one."

"Is that how you got your TARDIS?" Frisk asked.

"No I stole mine."

"You stole it?"

"Yeah. A long time ago. It's not really important."

"well what should we do now? you were listening earlier, right Doc?" Sans asked.

"Oh yeah. Thing is, even though this TARDIS is a complete mess, it still can be really helpful. We can use the pieces from it to help build the machine."

"alright. let's get started."