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Sans stood with one hand poised in a fist against Toriel's bedroom door, knees locked to keep him still. He waited for what felt like hours, mind numbly rifling through possible outcomes as he thought. His hand was slightly shaking as he silently stuffed it back in his pocket, quietly stalking away back down the stairs and making his way toward the makeshift laboratory in the basement.

There was simply too much work to do first. At least, that's what he was attempting to convince himself of.

The bulky machine had one gleaming metal corner sticking out from beneath the tarp carelessly tossed over it, and Sans lazily yanked the rest off before tossing the tarp in the corner. He gathered his strewn tools as he set to work on the cylindrical device, forcing his mind to stay on track regardless of how badly he wanted to yawn and crash onto the couch instead. Thick, coiling rods protruded from the top, winding through the machine and into the open center. The whole thing was shaped almost like a standing bullet, the solid steel door hanging open so that Sans could accurately adjust several loose wires.

Despite his attempts to stay awake, he found himself stifling multiple yawns as time stretched on. He could feel his head drooping as he struggled to screw a small metal plate over one of the exposed portions of the phase distortion generator, glancing occasionally back and forth between the hefty machine and the layers and layers of blueprints that he had sketched out, some with illegible scribbles and most written in hands. If he could just stay awake, there was still so much yet to do.

It would only take a while longer, he just had to keep reminding himself as-

-he walked silently down the corridor, arms full of papers as he struggled to keep the too large lab coat from falling off of his shoulders.

"Are you sure this is gonna work, doc?" Sans's voice echoed as he stalked beside the tall figure, although Gaster did not immediately respond. The skeleton only adjusted his glasses with a single hand, a large hole giving Sans an odd sight as they walked, monsters in similar attire as the pair almost tripping over themselves to stay out of Doctor Gaster's path.

"I have many doubts," the low tone of the tall skeleton rang out. "This is not one of them."

"But-but," Sans struggled to keep up with Gaster's long strides, "The last experiment with the DT extractor didn't manage to-"

"Whether or not the experiment survived is unimportant," he interrupted as they turned a corner, going through a pair of double doors. "It provided the necessary data that we needed to extract the remaining human souls and efficiently contain them. We are so close to freedom, Sans; we should not keep the king waiting any longer than necessary."

Sans bit his tongue as they walked, uneasy about voicing his concerns.

He could still hear the subject's last terrible moments bouncing in his head as the human was... 'harvested' for it's soul. Sans fought back a shudder, forcing himself to repeat Gaster's mantra.

All progress comes at a price.

"I just..." Sans started, shuffling the papers in his arms uncomfortably. "Is this really the most ethical way to save monsterkind?"

"It is the most efficient," Gaster said grimly. "That is all that matters."

"At the very least we could apply some form of... sedative, or-or something," Sans was almost pleading as they approached the large empty room, lights flickering on at their approach.

"Yes, understandable," Gaster nodded once. "At least that would quiet that unearthly racket."

"I meant because it's obviously painful," Sans frowned as they began flicking numerous switches and buttons, the large, almost skull shaped machine humming to life with a light blue glow emanating from within. "The least we could do is-"

"What?" Doctor Gaster snapped, turning sharply to the shorter skeleton. "Show them mercy?" he spat. "The kind that they never showed us? Don't make me laugh."

"I-I'm just saying..." he stood his ground, grip tightening on the bundle of papers. "We shouldn't make them suffer any more than necessary. It-it's not right."

Gaster didn't reply immediately, but he did let out a long, quiet sigh. Five small cylindrical containers slowly slid up from their slots built into the floor, each one glowing a different color. Sans could almost feel the souls crying out for release, the eerie glow radiating from the prisons casting long shadows over them.

"It isn't about what's right and wrong, Sans," Gaster explained slowly. "What we do here is going to save every monster in the underground. If a few humans have to be sacrificed for the greater good, then so be it."

"But the last one didn't even fight," Sans argued, forcefully placing the stack of papers onto one of the desks. "He couldn't have been older than twelve, and we just-"

"Prevented him from doing any more damage," he clenched one holed fist, adjusting his black necktie with the other as he distractedly began to run diagnostics at the large monitor. "Do you even recall what the last one did to the head of the royal guard? How many died because of him?" Gaster jabbed a thumb at the yellow glowing soul of the last human.

Sans couldn't find the right words.

"We do what we must, Sans." Gaster's voice was softer, but not any less bitter. "All progress comes at a price."

"It's not worth it if that price is the lives of the innocent, doc."

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A/N

Little bit of a dream sequence with Sans and Gaster. Getting back into the swing of writing, shouldn't be too much longer on the next (and hopefully larger) chapter. :D