The thing is, Sans has heard the tales. Has heard the evidence, situational as it often is.
Children who are abused often grow up to be abusers themselves.
Sans also knows that most of that is just a myth. People don't always grow up crooked, don't always turn into their parents.
He thinks about it, sometimes. Lies awake on their lumpy couch, staring up at the cracks in the ceiling, and tries to imagine Papyrus turning into his father. Tries to imagine him purposefully hurting a kid of his own, or even Sans himself. Fails.
He never tells Papyrus of his thoughts on the matter. No need to scare the kid, no need to give him useless thoughts on what will probably never happen.
Turns out, he doesn't need to.
Papyrus went directly up to his room after getting home, didn't even talk to Sans. Just scowled at him and muttered something about homework. Sans doesn't think anything of it; it's not the first time Papyrus had come home in a mood, not the first time he had ignored Sans.
He should have payed better attention.
It's when he doesn't receive a reply to his call for dinner that Sans begins to grow worried. Papyrus usually scrambles to eat, his teenager's metabolism craving food like air. He never misses the opportunity, especially in the increasingly often times it's just the two of them.
So Sans trudges up the stairs, gripping onto the railing to steady himself – today's been an off day, balance-wise. He hates days like this.
The sight that greets him is definitely not one he expected. He expected Papyrus to be consumed by his homework, or possibly lying in bed, scowling up at his ceiling.
Thing is, Papyrus hasn't cried since he was six, when his father finally had enough of his tears and pounded them out of him while Sans listened in the next room with a bottle of whiskey, forbidden from interfering or risk making it even worse. Yet here he is at sixteen, drunk out of his mind and sobbing into a half-empty beer bottle, at least five more strewn about him in a manner more reminiscent of Sans.
"pap?" Sans asks in surprise and not a little alarm. Papyrus takes one look at him and throws himself into his brother's arms. Sans just manages to catch him, barely keeping his balance with the aid of his tail.
"pap? w-what is it, what's wr-rong?"
And then Papyrus is off, wailing about how he's horrible, he's going to turn into Gaster and Sans shouldn't even be near him right now.
It takes some time, but Sans finally manages to glean what happened. Apparently Papyrus lost his temper today, punched another kid in the face so hard that they lost a tooth. The kid, Desher, had apparently bad-mouthed Sans and called him a freak.
Sans tries hard to ignore the warm, pleased feeling curling around his soul.
"pap," Sans says, pushing Papyrus away so he can see his face. It isn't hard. Papyrus doesn't put up a good fight while drunk.
"papyrus," he tries again, and the use of his full name has Papyrus's hazy eyelights meeting Sans's. "l-listen to me. you're not g-gaster. you will never b-be gaster."
"But what if I am," Papyrus whispers, and the sound breaks Sans's nonexistent heart. "How can you even stand to be near me Sans, I could turn on you, I could... I could..."
I could kill you, he doesn't say. Sans tries not to think about it, tries not to think about Papyrus being the one to snuff out his pathetic life.
Tries not to think about how he would probably let him.
"listen to me," Sans repeats, cupping the kid's face with only slightly shaking phalanges. "you're. not. him. you are so goddamned much more than him. you are good, the best fucking thing in this shithole, and you'll never change that much. can't change that much. i know you'll never hurt me because you can't."
Papyrus's sockets overflow once more and Sans draws him back into another hug. He knows he'll have to clean up later. Knows he'll have to hide the evidence before Gaster gets home, or there'll be hell to pay. But for now he just comforts his kid, bringing his tail up to wrap around him like he's trying to hide him from the world.
Maybe he is.
It happens one day when Sans is waiting for Papyrus's training to be over.
There aren't many kind monsters in the Underground. Sans knows this like he knows the ever-present ache of his head, where his magic digs into his skull like the particularly ill-fitting chest plate Papyrus tried to get him to wear once.
Gerson, however? Gerson is a monster from Before. Before the war, before they were all trapped down here to die.
Before Asgore went mad and installed the mindset of "kill or be killed".
Gerson studies Sans with narrowed eyes. Studies the way he shrinks in his sight, like an echo flower wilting in Hotland's dry air. Studies the way Sans can't stop shaking, the way his tail twitches a constant staccato against the ground, the way he won't meet anyone's eyes.
Studies the collar buckled around his neck.
He is silent, and it makes Sans more nervous than if he shouted.
(At least it's familiar.)
Finally, finally, he speaks, a low, croaking thing that makes it sound as if the old man is going to keel over at any point.
"You know, son," he says, and Sans stiffens at the word.
wrong wrong wrong i'm no one's son i'm nothing-
"If you'd like, I can help you."
Sans just sort of. Stares. Because declarations of help aside (and why does the guy even feel the need to offer it in the first place, that's what Sans wants to know), what does Sans need in the way of help anyway? Help with what?
The old geezer continues, and Sans immediately wishes he didn't. Wishes he just kept his ancient mouth shut.
"I can get you away from your brother."
And Sans freezes, because what? Why would Sans need to get away from Papyrus?
But the turtle's not finished. "Listen son," he says, in a voice that would be calming if it weren't so fucking confusing, "I know the signs. I can see it in your eyes, in your manner of holding yourself. In that Stars-forsaken collar," and here he spits the word like it’s a particularly vile insult. Sans's hands automatically go up to twine into the thick leather at his throat. "And I know that the two of you likely come from a less-than-ideal place, but that is no excuse for the way he treats you."
Sans blinks, shock beginning to calm the ever-present trembling of his bones. Because he's finally beginning to figure out where Gerson is going with this, and he doesn't like it.
Not one bit.
"b-boss doesn't ab-buse me," he says in an incredulous voice. It's all he can do not to add a bewildered what the fuck? because Sans is an idiot, sure, Gaster made it a point to drill that into him from the very beginning, but he's not suicidal thank-you-very-much. He knows better than to piss off a monster who could probably still hold his own against Asgore.
Gerson's eyes go soft and sad at the declaration, and Sans clenches a shaking fist because he's wrong. The bastard doesn't know anything, doesn't know Sans or Papyrus or what they've been through, and how dare he presume to know a single goddamn thing?
"l-listen," Sans says, snarls, and maybe he is suicidal after all. "b-boss isn't his father o-okay? he's not, and i-i won't just st-stand here and let ya say that about him!"
Gerson blinks at his declaration, started by the vehemence in his tone, shaky and stuttering as it was.
The turtle opens his mouth once again – probably to protest, Sans thinks, tail lashing around his ankles – but is cut off by the sound of approaching footsteps.
And normally Papyrus's voice would settle his nerves, would ease the knot of anxiety constantly curling low in his belly. But the thought of Papyrus overhearing their little conversation – or Stars forbid, Gerson actually confronting his little brother – only serves to make Sans tense up even more.
He looks over his shoulder. Papyrus is striding toward him, mouth set in a grim line. So his Royal Guard training didn't go so well today.
His eyes are narrowed at how close Gerson is to Sans. He knows who the old veteran is, of course – General Gerson, hero of the War and Undyne's adoptive father – but it's obvious he doesn't trust the monster.
That's okay. Sans isn't sure he trusts him either.
Papyrus's gaze sweeps over Sans, and his mouth tightens even more. So he noticed Sans's discomfort.
"HELLO, GENERAL," Papyrus says coolly, stepping close to lay a hand on Sans's shoulder. Sans relaxes ever so slightly at the touch.
Gerson dips his head in a nod. "Hello Sentry Papyrus," he says, voice just as cool. "I was just having a chat with your brother here."
"IS THAT SO?" Papyrus shoots Sans a questioning look, and Sans's eyelights skitter away from his face.
Papyrus's hand tightens on Sans's shoulder, and Sans doesn't miss the way Gerson's eyes go straight to the gesture.
"WELL, I AM AFRAID WE MUST TAKE OUR LEAVE NOW. IT WAS NICE TALKING WITH YOU, GENERAL."
Papyrus's tone indicates that it was anything but.
Gerson pauses but dips his head in acquiescence. The brothers are just turning to leave when Gerson speaks up once more.
Sans stiffens but turns anyway.
"My offer still stands. If you ever need anything, anything at all, I'll be here."
Sans's claws are digging into his palms now, dust flaking from his hand, but he nods anyway.
Papyrus questions him when they get home, of course he does. But Sans refuses to tell him what happened between him and Gerson. Papyrus is already stressing out over his position as Royal Guard trainee. Sans can't tell him of Gerson's suspicions.
Because he knows that Papyrus has dreams, sometimes, nightmares of becoming just like his father. And if Sans can't protect him from those, he can at least protect him this much.
So Sans gives his brother a shaky smile and pulls up a particularly bad pun from the recess of his mind, prompting his brother to screech in dismay.
But Papyrus's gaze is still sharp, and Sans knows that he didn't manage to distract his brother entirely.
(And if Papyrus is particularly affectionate tonight, gently scratching his claws against Sans's skull as they watch MTT tv, well. Sans doesn't say anything.)
There aren't many abuse cases that make it to the Royal Guard. Not that there's not a lot of abuse – Stars no, Sans can attest to that much – it's just that no one really cares all that much. No one looks twice at randomly appearing injuries, or someone scolding another in a tone that's just on this edge of too sharp. Because it's kill or be killed, here, and monsters can't afford to care about others.
So the few cases that do make it to the Guard tend to be especially bad, and mostly involving children. See, children are a bit of a rarity in the Underground, and as such are as protected as one can get down here.
Not that that stopped Gaster.
So when a child turns out to be abused, it's normally bad. Like, never-get-over-it bad.
(Like Sans bad.)
Turns out, that one monster kid? The little lizard with no arms? Well, apparently he wasn't born that way.
Sans wants to be sick, because who would do such a thing?
(He studiously ignores all the times Gaster removed his own limbs during the first few years of his life. That time is better off forgotten.)
When Papyrus makes it home from his meeting with Undyne, he is in a particularly foul mood. And Sans can't blame him, normally wouldn't try and intervene, except.
He knows his brother. Knows him better than he knows himself, and he knows that Papyrus is currently stuck in his own spiraling thoughts at the moment. That he is remembering his own abuse at the hands of his father.
(And some dark part of Sans thinks that Gaster's lucky he's already dead, because Papyrus isn't a babybones anymore. He has power now, and the training to back it up, and Sans, well.
He always would do anything for Pap.)
So Sans takes one look at his little bro and pulls him into a hug. Lets his brother give a shudder that shakes his whole body. Lets him break.
"it's o-okay boss," Sans whispers soothingly, running a shaking hand up and down his brother's spine. "l-let it all out."
And Papyrus does, breaks down into great ugly sobs, all heaving ribcage and snotty magic. Allows him to grieve for the poor child whose only mistake was being born into the wrong family.
And when Papyrus is done, he speaks.
"The Dogi are taking them in," he says, voice steady as ever even under the quiet hoarseness. "They have already killed the parents. They will raise the child."
It's a good choice. "d-dogamy and dogaressa a-are good," Sans says in what he only hopes is a soothing voice. "they'll t-take c-care of the kid."
Papyrus nods into his shoulder. "I only wish they didn't have to." He tightens his grip around Sans. "It's just... Seeing them like that... It reminds me of..."
Of him, Sans hears. Of what he used to do, to both me and you.
Sans doesn't want to think about it, because then he'll be the one to break, and he can't have that now can he?
So he only shushes Papyrus, pulling him closer into his arms, and wraps his tail around them both.
They remain that way for the rest of the night.