This wasn't one of his usual hiding spots, but it would do for now. It was an old bridge, it didn't really lead anywhere important and there were easier (and safer) ways to get around it but its lack of use made it the perfect spot to hide from Undyne who had become over bearing since she had been promoted to the head of the royal guards.
He knew the kid meant well and she only wanted to prove something but she was driving him up the wall (pretty literally yesterday after her spear was thrown at his head after one too many puns) with her demands he step up his game as a sentry.
He had cheekily, more then once, stepped on top of his sentry station at the demand and more then once sent running from a spear to the head, only being saved by his short cuts.
He sat, closing his eyes and happily taking in the silence and peace around him, legs hanging off the bridge and laying back, fully ready to nap.
Sans' eyes shot open as one of his slippers slipped off his foot. He would normally laugh at this but it fell fast, away from his fingers trying desperately to grab it, a few seconds too late. It was a slippery shoe, ok he did laugh at that one as he took one of his short cuts down to the bottom of the ravine, not ready to let his favorite shoe slip away.
He smiled imagining his brother's scowl at him making bad jokes now of all times while he had to wade through the garbage infested water, keeping an eye out for his shoe.
He had tucked his remaining slipper in his jacket pocket seeing no sense in two soggy slippers.
He grumbled loudly as he pushed large heaps of trash aside to get through, humans were frankly disgusting the way they just tossed their garbage where ever they wanted. The lakes and rivers that drained into their water supplies unfortunately ran through some human garbage dumping grounds according to the royal scientists newest findings and it just lead to this. Monsters having to clean up their messes to have access to water, it was depressing and made Sans hate humans more.
Lazily, he shoved another box aside but paused hearing something crying in it. He shoved it closer to the bank and tilted his head hearing the faint, little sobs coming from it.
"Napstablook?" he ventured a guess, he had witnessed the ghost squeeze themselves into the oddest of places just to have a cry.
The crying continued and Sans realized with a jolt that was an infant, too raspy and high pitched to the ghost's wails.
He popped the box open and found it stacked high with little baby cloths, he stared at the stack in mute horror. He instantly shook his head and prompted himself back into action hearing the raspy little cries under it all, he pulled back the colorful floral pattern baby blanket and once more felt himself staring stupidly down into the box.
He knew right away the tiny, sickly looking child was not a monster. It was human. A human threw away their baby. Slowly he picked the child up and stared at them then turning his disgust away from the child who began to settle down in his arms, little tiny fist weakly brushing curiously against his face.
They threw their child away…like they threw away the garbage around him. He looked towards a broken down engine that had washed its way down here, someone threw their child out like they were broken and useless. As if they had no value.
Sans couldn't properly describe the disgust he was feeling as he began to inspect the baby closer. They were tiny, malnourished and he was sure if he could smell, they would smell like death seeing the specs of vomit on their cloths and how heavy their diaper was under his hand.
There was a note pinned to them and Sans opened it up to get a better idea at what kind of human would do this to their own child.
He crumpled the note and threw it with the rest of the garbage in rage after reading the single sentence and starred with pity down at the child.
They had stopped crying, Sans merely holding them had calmed them and they began to doze off in the crook of his arm. Sighing he brushed a finger across their sweaty forehead.
"Hey buddy…" he said with a forced smile sinking down on the side of the bank. The baby didn't respond but began to whimper. Sans shrugged his jacket off and gently wrapped them into it to help keep some of the chill off.
He felt nothing but bones under the jumper they were wearing, while that would have been just fine for a baby skeleton, he doubted it was fine for a baby human.
He glanced into the box, seeing the baby cloths he scattered around, he noticed they all had tags on them. To keep his mind off things he read it out loud.
"Frisk Mart," he grumbled, he knew that name, most of the garbage tossed down here came from that mart, it must have been quite popular.
The baby brought him out of his scattered thoughts as they began patting his chest.
"Feeling Frisky?" he quipped making them smile continuing to pat his chest with their fist and becoming fussy as they got no food from the skeleton.
"Don't start gettin' fussy, stay frisky," he chided standing up once more, not entirely sure what he was going to do but knew they were going to die if he didn't act soon.
"Hold on tight, I know a short cut," he mumbled playfully to the child with a wink making them settle in his arms again as his attention shifted to them. He picked up the box and holding it lazily against his side and nestled the child closer to his chest as he disappeared.
As Sans disappeared, his missing shoe washed up onto the shore where he had been standing seconds before, a crumpled up note washed up next to it soon after.
Much later a very confused Napstablook would come across both but would be too depressed to return the shoe to Sans after reading the message on the note that would bring his spirits down again.
It's too much hassle… I'm not ready for the responsibility. I can't. I'm sorry.
