Sans the Skeleton (TwinSoul Au)

The first thing that hit you was the smell. It was a sharp, sterile scent, like lightning had been bottled and used to scrub the floors. It was the smell of ozone and cold metal, of antiseptic and things preserved in jars. It was the smell of a place that had forgotten what fresh air tasted like. You clutched the cardboard box in your arms a little tighter, the corners digging into your forearms. It held everything you owned that mattered: a worn paperback, a chipped mug, a single, smooth rock from the surface. Beside you, a second box floated an inch off the ground, enveloped in a faint blue glow.

"easy there, buddy," Sans said, his voice a low, easy drawl that felt utterly out of place in the cavernous, humming room. "don't wanna pop a blood vessel before we've even picked our bunks."

You tried to smile, but it felt like a grimace. The walls were a pristine, blinding white. The floor was a slick, reflective grey. A series of massive monitors on the far wall displayed a cascade of data and flickering security feeds. It was Alphys’s domain, a temple of science and anxiety, and now, apparently, your new home. A few feet away, the royal scientist herself was fiddling with a dial on a large, humming console, her claws clacking nervously against the metal. She’d explained it to you both, her words tumbling over each other in a rush. A human and a monster sharing a twin soul bond… it was an anomaly. A glitch in the cosmic code. The magic that tied you and Sans together, a bond usually reserved for two humans or two monsters, was creating a strange, fluctuating energy signature. It was unstable. It was, in her words, "a th-threat to the v-veil of normalcy."

So, here you were. In a lab. For observation. For your own good.

You set your box down on a nearby metal table with a soft thud, the sound echoing unnaturally in the quiet. You couldn’t help but wrap your arms around yourself, rubbing your hands up and down your sleeves. It wasn't cold, not really. It was just… impersonal. Clinical. Every surface was hard and unyielding. There were no soft edges, no shadows, no life. It felt like a place where hope came to be dissected.

From the corner of his eye socket, Sans watched you. He saw the way your shoulders were hiked up, nearly touching your ears. He saw the way your fingers were digging into your own arms, a nervous habit he knew you had since you were a kid. He saw the way your eyes darted from the humming fridge-like machine in the corner to the imposing steel door, as if mapping out all the exits. Your soul, a brilliant, warm pulse in his perception, was thrumming with a frantic, trapped-animal rhythm. It made his own soul, the inverted heart in his ribcage, ache in a sympathetic, hollow way.

"hey," he said softly, shuffling over to you. He didn't touch you, not yet. He just stood beside you, a small, solid presence in the vast, sterile space.

You didn't say anything, just flinched being broken from your mental spiral.

"alph's got a real eye for decor, huh?" he joked, gesturing with a bony hand. "real... 'mad scientist chic'. bet the feng shui is terrible for your health."

You let out a short, breathy huff that was almost a laugh, trying to act like it didn't bother you. Sans was sharper.

"Nah," Sans said, his permanent grin softening at the edges. "It's not. It's a lab. It smells like a hospital. And you hate hospitals."

He didn't say it as an accusation, just a statement of fact. He knew. He always knew. He remembered the time you'd had to get stitches when you tore up your leg in snowdin because of some glass, how you'd nearly hyperventilated in the waiting room, how the antiseptic smell had clung to your clothes for days and made you shudder. This place was that feeling, magnified a thousand times over, and it was now your living room.

He gave your arm a soft squeeze, his gaze steady and unwavering. He wouldn't let this place break you. He'd make puns until the humming drove you both crazy, he'd tell you terrible jokes until you laughed, and he'd sit with you in the dark. He'd fill this cold, clinical box with so much warmth you'd forget you were ever trapped.

"c'mon," he said, pulling his hand back and jerking a thumb towards the hallway. "let's go find the least creepy room in this joint. i'm thinkin' the one with the least amount of weird, glowing liquids."