If you haven't read Seven Human Souls prior to this, I would recommend going to check it out; this story starts where it left off and will reference it as things progress.
It took longer to get home than anyone would have expected, not counting the amount of time it took to get moving in the first place. Papyrus had been bound and determined to show Frisk every significant detail of their grave, which included guessing who'd left what in remembrance.
Despite what he'd said earlier, Sans didn't see any reason to rush them; he was happy to trail after and offer bad jokes while Papyrus ushered Frisk around their own burial site. Reality only hit after they reached the dent Undyne had left in the mountain.
Ultimately, this was fantastic news, but just barging in with a skeletal child- recognizable only by the tatty sweater they were wearing- was probably not the right approach.
Sans gave the matter literally seconds of thought before dismissing it. Sure, his original intention for the night had been to wallow in guilt and make an already bad day worse, but that plan had gone out the window some time ago. Right now, he was happier than he'd been since reaching the surface, and he didn't want to lose that feeling so soon.
He looped around the marker to the memorial side and rested his arms on top of it, watching Papyrus gesticulate rapidly from token to token. Frisk picked up a soggy cardboard box by one corner and looked utterly unsurprised as it dissolved between their fingers and flopped back to the ground. They stared at their own hand for several seconds before turning their attention to the mess they'd made- and the mildewing pieces of torn construction paper that had been inside of the box.
Papyrus made a scandalized noise and tugged them away from it, tutting about germs and eying the bar of soap Woshua had left with clear intent. Midway through concocting the perfect hygiene pun, Sans leaned his head against his arms and, moments later, fell asleep.
It was well past nightfall when something roused him again, and it took a second to realize that it was the sound of his name being called. That was nothing new. Every other time he dozed off, that was how Papyrus woke him up, so he was pretty used to it.
When the way his brother was calling registered, he stiffened and pushed away from whatever he'd been sleeping on, only to stumble backwards and fall flat on his tailbone. He stared up into the darkness for a moment, trying to figure out what he'd missed. He remembered the memorial. He remembered Frisk. He had no idea what about the situation would make Papyrus sound like that.
He scrambled back upright and caught a flash of red light on the other side of the grave. Obviously it was magic, but he didn't know whose- and he wasn't going to wait around and find out. Somewhere in the dark, Frisk made a pitiful squeak, audible only for a second before they muffled it, but it told Sans that they were entirely too close to the foreign energy.
Though it wasn't a substantial distance, he still warped the fabric of space to make it shorter, already prepared to lash out if need be.
As the teleportation magic rapidly faded, the red flared up- stronger than before and bright enough to literally shed light on what was going on. One small bony hand balled up around the edge of Papyrus' scarf and, trembling, Frisk buried their face in it. The magic immediately dimmed, but didn't vanish. As a matter of fact, it was doing a very good job of illuminating the scarf in question.
Sans let his defenses drop- it was foreign magic, but not a foreign source. Fair enough. As a human child, Frisk hadn't known how to use magic, so this probably shouldn't have been a surprise.
The light emanating through Papyrus' scarf flickered and, finally, went out.
"Huh." He finally said.
Papyrus shot him a look and tightened his grip on Frisk. They hiccupped and red blipped into existence for half a second before dying back down.
"Uh, well, that's normal for younger monsters, isn't it?"
"I don't know! Is it?"
"I- yeah? Maybe?" He stuffed his hands in his pockets and meandered closer, "Honestly, I have no idea. But, uh, they wouldn't know their magic, right? So we just gotta get 'em used to it. Theoretically."
"What theory? You just said you had no idea!" Despite the petulant nature of his vocabulary, Papyrus did seem to take solace in the explanation. He hooked his jaw over the top of Frisk's head and spoke more gently than Sans had heard in several years. "Did you hear that? Don't worry hu- Frisk! There's no need to be afraid!"
Frisk took a stuttering breath and curled closer to him, though they did shift to look past the arms wrapped around them and peer at Sans.
Without taking his hands out from his pockets, he shrugged. "You're made'a magic- you'll get used to it pretty quick. Gotta think the more exposure you get to it, the easier it'll get. That's how monster kids learn anyway."
"We should go home, then!" Papyrus announced; despite the proximity and volume, Frisk didn't flinch at the sudden noise.
Sans sidled up and, conspiratorially, added, "Actually, it's Newer Home. You know how it is. Naming stuff's hard."
Papyrus ignored the comment. "There's plenty of magic there!"
"And when you're ready, we can reintroduce you to everyone." Sans paused and shot the marker a sideways look. "Or when they're ready, I guess. It's comin' up on a year since the barrier broke, so we might wanna be careful about that."
They perked up and, in their visible eye socket, a pinprick of light fluttered. "Toriel?"
He hesitated, remembering how excited she'd been as they'd trailed in everyone's wake that first evening atop Mt. Ebott- how she'd gone from the usual small talk and back-and-forth to vague plans for the future, helping Frisk settle whatever business had them nervous and potentially creating a home of their own on the surface. It was hard to revisit that without remembering the devastation that followed, too.
With the anniversary of Frisk's death on the horizon line, it would be better to approach her before she had the chance to dwell on it.
"We can probably swing that- Tori's a busy lady nowadays, but I bet she'll be able to make time for you."
"Possibly too much time." Papyrus said, expression twisted in thought. "But maybe that would cut the insufferable joke onslaughts short."
"Hey, you can't spell 'onslaught' without 'laugh', bro. And you know what those 'joke onslaughts' are good for?"
Papyrus did a nasally impression of Undyne's battle cry, but, otherwise, didn't respond. Frisk patted his humerus sympathetically, without seeming to notice the irony inherent in doing so.
"I knew you'd understand." When this failed to elicit a response, Sans followed it up with, "Wanna go home now?"
He got a one-word response: a petulant "Yes."
"Alright, one shortcut comin' up."
They made it most of the way before Frisk's magic started acting up again and, to avoid any dimensional unpleasantness, Sans ripped out the magical sutures holding his 'shortcut' in place. It wasn't quite home, but the city was better than Mt. Ebott, even if the landing was a little rough.
Further shortcuts were probably not a good idea and, truth be told, Sans didn't really know his way around without a little cheating, which made it a difficult situation.
Papyrus hoisted himself back up, dusted off his battle body, looked around and then back down at the smaller skeletons splayed out over the pavement. Without any hesitation, he slung them over either shoulder and took off at a gallop.
"No need to worry! I have a plan!"
"Uh, you know where you're goin', bro?"
"Of course I do! The Great Papyrus always points due north!"
Frisk craned to look at Sans from around Papyrus' skull; though they weren't in possession of the regular human facial features, their half-lidded eye sockets still managed to look expectant.
Of course, Sans didn't process this until after he'd already drawled, "I guess that makes you the northster then, huh?"
Papyrus skidded to a stop at the corner of the sidewalk and turned to glare at the back of Sans' skull.
In the end, they wound up riding the north-bound skeleton across half the city until Papyrus recognized where they were. Sans dozed off again before they'd gone three blocks, leaving Frisk to observe the monster-dominated civilization while zooming past the majority of it.
It was a surprisingly smooth ride up until they reached one particular apartment complex and Papyrus started charging up the stairs two at a time. At the first landing, they squirmed enough to get his attention and, from there, did their best to keep the pace trotting after him. Sans didn't even seem to notice how bumpy the ride had become until Papyrus slowed down, and stayed quiet for as long as he could. Or, at least, until the opportunity for a bad pun arose.
"Do not fear, Frisk, we're almost there! The door to floor four is right up there! Stay determined!"
"Yeah, looks like someone's run a number on you, but you got this, right?"
Papyrus stopped cold, one foot on a step above the other, and seized Sans by the hood of his jacket. As he always did, Sans just grinned up at him, though, truthfully, losing the rest of his free ride was something of a disappointment. Perhaps in compromise, Papyrus stuck to a more reasonable pace.
"That might have been a mis-step."
For a second, he had no idea what the look Frisk was giving him was supposed to mean. He had a talent for reading expressions, but the sudden change in features was jarring. Not that he had to tell them that- they were probably well aware.
Then Frisk called to Papyrus' hunched shoulders, "Don't take the bait, just walk away," and there was that mystery solved.
"I am!" There was a second of silence as he held the stairwell's door for them, and then, "…that was another pun, wasn't it? Sans! You're corrupting them!"
"Yeah? My kinda job, then. Barely had to do anything."
Down the hall, a door slammed with impressive force. The cracking sound suggested that it had been too much force and that said door hadn't actually survived.
"Ngahhh! I don't have time for this! I'll deal with you when I get back!"
Papyrus' eye sockets lit up and he jogged forward, ready to greet Undyne. Sans, however, tugged Frisk further back and, when he couldn't think of any convincingly bad puns or ways around encountering Undyne, scooped them up and zipped his jacket after them. Wouldn't be the first time she'd think he was trying to smuggle something in.
Frisk grumbled through the fabric, audibly irritated.
"Cool it, kiddo, it's just for a minute. Hold still or she's gonna catch us."
They stopped struggling. With one arm around his middle to support them, Sans sprinted after Papyrus just in time to hear, "- sure it's gotta be AWESOME, Papyrus, but I really gotta be going. Alphys's streaming the Dragon Maiden Beta finale from wherever and if I miss it tonight, there'll be spoilers everywhere I look tomorrow- an' I can't ask Al to wait just 'cause I'm a jerk who runs late. But when we train tomorrow, SCREAM it at me, okay? Can't let all that enthusiasm go to waste! See ya!"
She took three running steps, spotted Sans, and stopped abruptly.
"Don't have time for this crap tonight, Sans. Not even gonna ask what you're tryin' to pull." She announced before launching herself forward again.
When she was safely down the stairwell, he unzipped the first four inches of the jacket. "Just gonna throw this out here: probably best you didn't hear that. You didn't hear it, right?"
Frisk shrugged and scrambled to support themselves on his shoulders.
"Works for me." Unceremoniously, Sans undid the rest of the zipper and caught them around the waist before they could fall down. "Yo, Pap, what'd you tell Undyne?"
Though it was hard to tell with the padding, Papyrus' shoulders drooped.
"I know I wasn't supposed to say anything, but Undyne's had such a hard week! I just wanted her to know there was good news!" He looked down to Frisk's level and blinked. "…now that I think about it, though, it might have been difficult to tell her there was good news without explaining what the news was. Hm. This requires further consideration."
"And pasta?"
"And pasta!"
Good mood back in place, Papyrus charged on ahead to ready the kitchen. As he set Frisk back on their feet, Sans made a mental note to ready the trash can too. It wasn't quite a deep thought, but it was still enough to distract him; the next time he spared them a look, they were only just keeping the pace, staring at the passing walls blankly.
There had to be something wrong if they were falling behind him.
"What's rattling around in that skull of yours?"
Frisk started violently. While they were watching him, Sans reached over and knocked on their vertical plate.
"Nope, not hollow. I'd say spill your guts, but that joke's a little bare bones."
They stared at their hands and flexed their fingers a couple of times.
"Huh. Too soon?" Again, they shrugged. "Adjusting's probably gonna be tough, so let's just get a good day in before then. 'Why do today what you can put off until tomorrow' and all that, right?"
Frisk stared at him as the two of them moved along, continuing to clench and unclench one bony fist. With the other hand, they felt along their upper jaw.
"How do I eat it?"
"Eh, same way anyone else does, I guess: ditch it when Pap's not looking."
"But how do I try to eat it?"
"Honestly, it's magic. Sounds like a copout though, I get that." He tucked his hands away in his pockets and winked at them. "Tell you what, we can put a couple a 'dog buns in the toaster and treat them like breadsticks. Papyrus'd get a kick out of it, and you can experiment with solids before graduating to noodles. They can really stick to your ribs if you aren't careful- better to get some practice in."
"Sans." Frisk stared at him gravely, hands on either side of their face and, finally, he realized what they were getting at.
They did seem to be lacking in the lower jaw department.
Sans took a moment to consider this new development and, finally, shrugged. "You'll figure something out. It'll be jawesome."
They made a strangled noise and launched themselves at him. Rather than putting the effort into dodging, he allowed the full force of a seven-year-old's skeletal system to ram into him. Out of politeness more than anything, he even flopped backwards when they connected.
In the face of such success, Frisk didn't seem to know what to do with themselves. For several seconds, the pair stared blankly at one another and then, without moving from their newfound perch, Frisk looked away.
"I'm happy." They said, but the way their eye sockets drifted down to the carpet suggested there was more to it. "I- I didn't think I could…
"I'm really happy, but I'm scared too. Really scared."
Sans propped himself up on one elbow, and, even staring directly at them, found himself reaching up to ruffle their hair before realizing that it wasn't possible. "Yeah, it's… yeah. Don't stress about it too much, eh? We're gonna take care'a you."