"Sans."

Grunt.

"Sans."

"Guhhh..."

"Sans, this is important!"

Sans slowly opened up a socket, only to be greeted by his brother's eager face filling his entire area of vision. He sighed.

"Papyrus, we've talked about this. I need to sleep on Sundays; they're my day off."

"I know, I know, but this is important!"

Sans sighed again, then sat up, resting his cheekbone on his fist as he looked at his brother. "All right, bro. Tell me what's up."

Papyrus jumped up to his full height, practically bouncing in place. "I've been talking to Undyne!"

Sans managed a tired, little smile. "I heard you've been following her for the past few weeks. Guess she's real spears-cial, huh?"

Papyrus' excited grin promptly dropped into an expression of annoyance. "Sans, this is serious."

"No, no, I know. I'm dyne to know wh—"

"Sans!"

Sans laughed. "All right, all right, I'm done. What's Undyne say?"

The excitement promptly returned; Sans half-expected Papyrus' neck to start stretching. "She says that, if I can make my own special attack, she'll—listen, listen!—she'll consider letting me do training to join the Royal Guard!"

Sans yawned. "Very cool. Glad you told me. I'm gonna sleep for a bit more."

"Wait, wait! I need your help!"

Sans opened his eyes again. "Huh?"

Papyrus rocked himself on the balls of his feet. "Well, I mean, you already know your special attacks. So I thought you could show me what to do. I can do normal bone attacks—I can even do some really cool ones!—but special attacks..." He gave a helpless shrug. "So maybe, since you don't have work...?"

Sans sighed and rubbed his forehead. The plan today was to go back to Gaster and work out more on these resets. Apparently he'd managed to get a few monsters who had the strange déjà vu feeling and were willing to look into it with them. They'd be coming tomorrow, so today was for researching and coming up with a clear game plan of how to proceed with the research. Not to mention that the Royal Guard was thelast place he wanted his baby brother to be. But...god, the way Papyrus was looking at him with those puppy-dog eyes (though how he managed to do that with no eyes was a mystery.) He shook his head.

"All right, here's the deal, Pap. I've got something I really need to do today. It's really important. But...but I shouldn't be out too late. So when I come back, I promise we can practice and start figuring out a special attack for you. Deal?"

Papyrus looked at his brother suspiciously. "Is this a normal promise or a real promise?"

Sans blinked. "What do you mean?"

"Well, because you always say 'I promise' and then it doesn't happen." He started ticking things off on his bony fingers. "You promised to explain what your job is, you promised you'd practice with me two weeks ago, you promised you'd watch Mettaton's Winter Spectavaganzabration with me...but then you don't."

Sans inwardly squirmed as Papyrus laid out the different ways he'd let him down; god, did he really promise that much? He never even thought about it.

"I mean, I understand your work is very important! And that you do a lot!" Papyrus quickly added. "And I figure you must always have a good reason for not doing things with me!"

Goood, that made it so much worse. Sans covered his face; the last thing he wanted to do was let down his brother again. He was just so...trusting.

"No, really, this time I really mean it," he assured once he looked up. "We'll make sure you have the most kick-ass special attack." He gave an uneasy smile. "They'll be begging you into the Royal Guard."

Instantly Papyrus was back to Lesser Dog levels of excitement. "Really? Do you think so?"

Sans smiled. "Absolutely." He got up and stretched. "Why don't you practice making your bone attacks super cool while I'm out? That's the first step to getting a good special attack."

Papyrus nodded eagerly, jumping up and bounding away with a bright "NYEH-HEH-HEH." Sans smiled after his brother, then got up. Once they finally got out of here, he'd need to spend more time with Papyrus. And stop breaking so many promises.

To his surprise, Sans actually really enjoyed all of this science stuff. He'd pored over the notes Gaster had given him, reading as carefully as he could until the words actually made sense, and coming over for his lunch breaks to discuss parts of it he didn't understand.

So far, based on each other's experiences and Gaster's theories, they'd been able to surmise that there was a high chance of time travel being possible in the Underground. Whether it was contained to humans alone or monsters as well remained to be seen, but hopefully the group they would get together would be willing to help. This project was far too ambitious for just two monsters—they were already swamped with the information they had to sort through and think over now.

But Sans wasn't about to be overwhelmed. He had three different books open and was jotting down as many notes as he could, not letting any stray thought get away. With such an intense focus, he nearly fell off the chair when a cup and saucer clanked down beside him. He looked up to see Gaster giving him a smile before sitting beside him.

"I think now would be a good time for a break," he said, taking a sip from his own cup. "You have not looked away from those books since you came in."

Sans gave a wry smile. "Well, I'm trying to think like a scientist."

Gaster smiled proudly. "It is always nice to see someone find enjoyment in this work, particularly when it is something new for them." He nodded toward Sans' notes. "Do you mind if I take a look?"

Sans shook his head as he blew on his tea. "Go ahead. Dunno how much sense it makes, though; I was just writing what came to mind."

Gaster leaned over and took a few of the pages, looking them over quietly as he sipped his tea. His browbone rose, and he glanced up at Sans. "Your language is rudimentary, yes, but you surprise me with your process. It is quite sound."

"Heh, really?"

Gaster nodded, looking hard at Sans' notes before grabbing a page of his own. He examined both in silence for a moment, then looked back up at the other skeleton. "Your conclusions are the logical extensions of my own," he murmured, more to himself than Sans, but he looked up with a bright smile. "Have you considered going into science before?"

"Me? God, no," Sans said with a laugh. "I always figured I was a...y'know, brute-force kind of guy."

Gaster set the notes down and took his cup again. "Ah, yes. I forget that being Judge is primarily a defense position." He took a sip. "How did you come to that position, if you do not mind answering? You are very young."

Sans frowned. "Not that young. Undyne's head of the Royal Guard, and she's younger than I am."

Gaster sighed. "Yes, I suppose that is true. Another effect of life down here. You are forced to grow up very fast."

Sans smiled wryly as he set his empty cup down. "I would have anyway. Mom and Dad checked out pretty early."

Gaster gave Sans a sympathetic look. "In the war?"

The smaller skeleton shook his head. "Nah, Papyrus and I were both born down here." He shrugged. "I don't know what happened, really. Maybe the change was too hard on them or something." He smiled wryly. "Or maybe me and Pap are boss monsters and we just don't know it."

"I am sorry, but I do not think that you would be..."

Sans waved his hand. "It's a joke, Gaster, don't worry. I know I'm not a boss." He let out a little huff, resting an elbow on the table. "Papyrus doesn't remember much about them; he was still in striped shirts when they went to dust. So I've taken care of him since then. That's why I took the job when Asgore offered a few years ago; it gave me a way to make sure Papyrus was taken care of while he grew up." He rubbed his neck. "I do wish I could spend more time with him, though...wait." He looked down at his watch. "Shit! Is it really this late?"

Gaster blinked, then looked at the industrial clock on the wall. "Yes, your clock is correct..."

"Shit shit shit!" Sans launched himself off of the chair. "I need to go! I told Papyrus I'd help him hours ago!" Without so much as a goodbye, Sans bolted back out to the Core.

He made it through the core in record time, bursting through their house's door hard enough to strain the hinges.

"Pap! Hey, Papyrus!" he called as he ran inside. "Pa...oh."

Sans found his brother sitting on the sofa, obviously in what he would consider his "battle clothes," and fast asleep. How long had he been sitting here, waiting for Sans to come home? Sans let out a sigh as his brow knit.

Another promise broken.

He stood for a moment, watching Papyrus snooze as guilt washed over him. A few years ago, he would have been able to pick him up and carry him to his bed, but that was hard now, what with his little brother being almost double his height. He took a breath and held up his hand, left eye a soft, glowing blue. As gently as possible, he lifted Papyrus into the air, trying not to wake or hurt him. Slowly, very slowly, he carried him up to his room and laid him on the too-short mattress. Papyrus stirred and mumbled something, but didn't wake up. Sans took the opportunity to pull the blankets up over the sleeping skeleton, then sighed.

"One day, buddy. One day I'll have time," he murmured, then headed back to his own room for what would no doubt be another sleepless night.