With the new revelation that monsters could reset, the researchers were all in a flurry to collect as much information as they could. Sans laid out everything he had done in the plainest terms he could, and he and the other seven researchers discussed the possibilities and results.

"So, like, I didn't feel anything when you reset," Ceris said, fiddling with her camera strap. "But I guess I wouldn't, right?"

"Come to think of it, that day did seem a little weird," Tephra added with a frown. "When we all met."

"Or you're just remembering it as weird," Wynn pointed out. "Because now you know that Sans reset."

"But it was like we all already knew each other!"

"Might have been my fault," Sans said with a shrug. "I mean, I did know all of you, and, uh, I wasn't that great at pretending I didn't."

Terrin glanced around, then leaned in to whisper, "Hey, Gaster isn't here, right?"

Sans shook his head. "He said there was an issue with the other experiment, the one he's doing with his assistant."

Her fins perked up. "So tell us what the differences are between the first timeline and this one."

Everyone leaned in expectantly, and Sans rubbed his top vertebrae. "Uh, well...I went to Grillby's with you guys a lot more?" He shrugged. "Other than that, it's really been the same. I didn't change anything drastic. I mean, there's the teleporting, but that's it. And I only went back about two months."

Terrin tapped her lips. "So...for us to really know what could happen, more than one of us needs to reset." She sat up straight. "And take notes of what happened!"

"But we can't do it all at once!" Ceris added. "Because, like, that will really screw up the timelines. But if we all do it, just once..."

"We'll have tons of data!" Wode, a small dinosaur, added brightly. Wynn frowned and shifted.

"But Gaster said we should only do it if it's a necessity," he said. Terrin grinned.

"So we don't tell him." She pointed at Sans. "And you don't tell him, either!"

"What?"

"We all know you guys talk all the time, but this time you need to keep quiet. Otherwise, there'll be no way for us to compare our experiences."

Sans grimaced. This...was not what he had planned for this discussion. But they did have a point. They needed more data. He huffed.

"All right, I'll keep quiet. But if anything goes wrong, we go stop and go straight to Gaster."

Terrin waved. "Fine, fine! We'll figure that out later. For now, we should make a schedule..."

~

Research continued over the next couple weeks. Every now and again, someone would show up with a bit of their tail missing or a little shorter than they were before, but always with a big smile on their face. Strangely, it seemed that only Sans and the other few who had reset could notice these things, though no one outside of the resetter could recall a reset actually happening. With Gaster out more and more frequently, either to the restricted Lab below or to Asgore, they were able to discuss the possibilities. Were those who reset more sensitive to these changes? Did messing with timelines put you outside of time? Soon enough, it was clear to Sans that it was time to let Gaster in on what was happening.

After they broke for the day, Sans waited in the lab for Gaster to return from below. One hour went by, then two...finally, the door to the restricted Lab opened, and Gaster walked out wearily, with a yellow, nervous-looking dinosaur following him.

"But, I swear, with the first test subject, it was a..." she was saying, then stopped as she noticed Sans sitting on the stool. She broke into a sweat. "Oh...erm, hi...?"

Gaster looked up, and he sighed. "Have you been here for long?" he signed, hands moving slower than normal.

"No," Sans lied back. Gaster nodded, then gestured to the dinosaur.

"This is Alphys, my assistant," he introduced aloud. "She has been aiding me in the other, er, more official project I have been working on." He glanced down at Alphys. "Alphys, this is Sans. He is..."

Sans signed a quick "Do not tell". Just looking at Alphys told him she'd freak out if she heard his real job.

"...the head, I suppose, of the research we are doing into resets."

Sans smiled, then walked over and held out his hand to shake. "Nice to meet ya."

Alphys managed a painful-looking smile as she limply took Sans' hand. "Uh...same." She glanced between the two. "Er, um, maybe...we could talk about this...later?"

"I think that is best, yes," Gaster agreed. "Go home and rest. It has been a trying day."

Alphys nodded, gave Sans an awkward "bye", then headed out the door. Gaster watched her for a moment, then practically dropped into a chair, covering his face. Sans shifted his weight from one foot to another.

"So, uh, rough day?"

Gaster gave a wry smile. "To...what is the phrase? To put it lightly." He sighed. "I do not think I can manage a lesson today, Sans."

"No, no, that's not why I'm here." Sans' browbone furrowed as he sat down. Maybe now wasn't a good time to bring up the resets. "Uh, so what happened?"

Gaster huffed, looking up. "I am afraid I cannot divulge the details. It is strictly between Asgore, Alphys, and myself. But...well. It is a containable problem, but not an easily fixable one." He looked over at Sans. "Have you heard of Determination?"

Sans shook his head.

"It is...well, it is difficult to explain. It is a trait widely found in humans; it is, in its simplest definition, what enables them to continue fighting rather than retreating. But we have found certain monsters—well, one, at the moment, though I have my theories on others—who possess it as well." He shook his head with a sigh, shutting his sockets. "Perhaps I will explain more another time, but for now, I am very tired."

"I can...I can go, if you want."

"No, no, it is quite all right. Tell me why you are here."

Sans looked down again. "I, uh...I just wanted to talk. Y'know. About what things were like above ground." He smiled weakly. "Maybe try out a few jokes on you; Pap can't seem to see how humerus I am."

Gaster chuckled, then sighed. "You know, I have not had the chance to say it, but I am very glad that your reset was a success. It has been a long time since I have had such a...an amiable companion..."

"You could just say friend, you know."

"Yes, yes, I suppose I could. It has been a long time since I have had a friend, and it would be a terrible thing if you had dissolved...tibia-nest." He cracked a socket open with a smile as Sans let out a loud laugh. "Where would I have learned this language's wordplay?" He sat up. "Now, you said you wanted to hear more about above?"

~

A week went by. The six other researchers carried on as normal, Gaster was still absent with his other project, and Sans continued keeping the secret. He had gone from part-time to on-call with Asgore and Papyrus had been sort of accepted to the Royal Guard as a part-time patroller, no doubt to keep him from bothering Undyne as much about being brought in.

Today was no different, save for the fact that Gaster was actually with them. However, their discussion was violently interrupted by the sound of metal crushing against metal. Everyone jumped back as the doors to the lab were kicked in, and a heap of armor burst into the room, gasping out, "Sans!"

"Undyne?" Sans stepped forward with a frown as Undyne tore off her helmet, breathing hard. "Quick, someone get her water!" he ordered, then turned back to her. "What is it? Is there a human?" That would be the only reason they would speak, but normally she'd go to Asgore first. What could be wrong?

Undyne shook her head as Wode brought over some water, and her one eye blinked very quickly. Was she...fighting tears? That would be the last thing she would fight. She took a deep breath, getting herself together enough to wheeze out, "I...I sent him to the wishing room. I thought..." Her voice broke. "I mean, nothing ever happens there!"

A chill ran down Sans' spine. "Who did you send?"

Undyne swallowed. "He just...he wanted to patrol so bad..."

"Who did you send, Undyne?"

She was silent for a long moment, then held up the plastic bottle she had been holding, filled with white dust.

"I...I got what I could."

Everything came to a grinding halt. Sans felt his chest constrict as he stared at the bottle, brain full of static as his hands mechanically took it. Gaster said something to him; he could almost hear Undyne punch a wall. But none of this was registering.

Something had killed his baby brother.

The static grew louder, to where the only other thing he could hear was his breathing, getting harder and harder the longer he stood. A fluttering hand settled on his shoulder, but he savagely shrugged it off.

With a small rush of wind, he was gone.

~

The wishing room was disgustingly peaceful. There were soft murmurs from the echo flowers, and the crystals shone brightly overhead. Sans held the bottle close as he appeared in the room, the plastic crinkling loudly. This was where his brother had died. Somewhere that was supposed to be safe for monsters. He drew in a jagged breath as his eyes locked on the bits of white dust up ahead, illuminated brightly by the crystals' light. His legs wobbled as he took a step forward, but he froze as he heard Papyrus' voice.

"Wowie! A talking flower!"

His head turned to the source, hoping that maybe, possibly...but no. It was just an echo flower, repeating the same line over and over. Had they recorded all of Papyrus' last few moments? With a sick curiosity, he walked up to the next one. He needed to know what happened.

"Well, golly, are you a member of Royal Guard? You sure look like you are!"

Despite the cheery tone of the voice, a sick feeling coursed through Sans. He knew that voice, he knew that it belonged to something...terrible. But where had he heard it before? He pushed himself forward to the next flower.

"I am! Well, sort of! I'm in training; that's why I'm patrolling!"

Sans took a shaking breath, feeling the bottom of his sockets grow wet. God, why was Papyrus so trusting? Why hadn't he seen that this thing was bad? He held the bottle as close as he could, plastic pressing against his ribs as he walked.

"Well, gee, maybe I could help you train? I'm sure you have a great special attack! But go easy on me; I'm just a flower!"

God, that voice! Sans got away from it as fast as he could. The next flower was a ways off; each step made his chest tighter and tighter. When he finally got to it, it was a cacophony of shots and bones clattering. He could just barely make out the two voices in the repetitions.

"Wait, what are you—"

"You're such an IDIOT!"

Finally, he pushed himself to the last bit of dust, trying to keep himself from collapsing in front of the final flower. The static was back, and he could just barely hear what it whispered.

"You weren't as fun as your garbage brother."

Sans was trembling hard; he could barely keep his hold on the bottle. It took several minutes before he could even force his brain to think. When he did, one word kept repeating.

No.

No, no, no, no, no.

Papyrus couldn't be dead! Not now! Not when he had just gotten the chance to get to know him! A whimper escaped him as he practically hugged the bottle. He needed his brother back. Nothing would matter if he was gone.

But...

There was a way.

He just needed to—

"Sans!"

A breathless voice stopped him mid-thought, and soon all the echo flowers were repeating his name. Sans turned to see Gaster, out of breath, trousers and lab coat soaked to the knee, standing at the opening of the room. As he regained his breath, he began signing frantically.

"Sans, Sans, I realize this is painful. But you must not do anything rash!" He looked up with a pleading expression. Sans remained silent, hands still wrapped tightly around the bottle. He continued, speaking aloud but signing the words he couldn't immediately think of. "We have already seen the effects of resetting. I know...I know you think your teleporting is an improvement but there is a very large possibility that another reset will be damaging! You may even dissolve!"

Sans' mouth twitched, and he adjusted his hold on the bottle. They both knew what he was about to do. Gaster shook his head.

"Do not be selfish, Sans!" he pleaded. "So many things could go wrong if you dissolve! Think of how the timelines will be affected! There will be no way to continue the research! We will not be able to stop whatever is causing the resets!" The scientist fell silent, jaw trembling as he locked his sockets with Sans'. His voice grew soft and hoarse, and his fingers fluttered weakly. "Please, Sans. Please do not leave me to be the last of our kind."

Sans blinked, two tears finally spilling over his cheekbones. He set the bottle down with a shuddering breath, then met Gaster's gaze as he held up his hands to sign one thing.

"I'm sorry."

"No, no, Sa—"