Gaster hummed contentedly as he finished packing the picnic lunch he had prepared. It was nice and hot now, and wrapped in several layers of fabric to keep it that way for as long as possible. At the very least, it wouldn't freeze before lunchtime; his calculations had confirmed this. Now all he had to pack was Sans.
He froze where he stood and glanced around the kitchen. Where was Sans? He couldn't remember where he had left the baby skeleton.
"Sans?" He knew there would be no answer, but he called anyway. "Sans, where are you?"
He went into the living room, and couldn't find Sans in there either. He checked under the table, behind the large and dangerous machine of questionable purpose that he kept across from the couch, and then lifted up the couch cushions to look in there. Nothing but money.
"SANS" he screamed, and flipped the couch over with a forceful sweep of his arms. As coins jangled across the carpet, Gaster rushed toward the kitchen to search the cabinets and refrigerator. Halfway there, a motionless blob of white caught his eye.
"Ah. There you are." He approached the table to see Sans sitting exactly where he left him. The skeleton's body was roughly the size of a guinea pig, with a head nearly twice as big. He was lying on his belly on top of a hot dog bun, chin resting on the table.
"Are you finished being a skele-bun, Sans?" Gaster cooed. "My, you don't even fit in there anymore. Come on, let's go for a walk." He scooped up the tiny skeleton in both hands and began to carry him to the kitchen.
Gaster had dressed the baby in little white one-piece pajamas made of the softest material known to monsters. Even now, he marvelled at how soft it was - soft enough for a skeleton to feel, despite not having any skin. He had made it in the lab, and couldn't resist making himself a sweater with the material. He wore that sweater every day, and Sans seemed to enjoy wearing his pajamas.
Gaster's thoughts were interrupted as Sans suddenly squirmed out of his grasp and dropped to the table. He wriggled his way back onto the hot dog bun and nestled there comfortably. The expression on his face remained constant, a vacant grin and eyes staring distantly in slightly different directions.
"Sans," Gaster scolded gently, "you've been on your bun for far too long. You need some mental stimulation." He grasped the baby again, more firmly this time. "Come. It's time for a walk."
Gaster strode into the kitchen and placed Sans on the counter beside the still-warm basket. He draped a small blue blanket over the bundle of food, then carefully positioned Sans on top of it. "That should keep you nice and warm," he murmured. He folded the blanket over the tiny body, leaving the face free to gaze out at the world. At last, it was time to go.
Balancing the weight of the basket on his arm, Gaster threw open the door and slammed it behind them. He paused for dramatic effect and screeched into the cold morning air, "PEOPLE OF SNOWDIN! I, THE BRILLIANT DOCTOR GASTER, AM ONCE AGAIN PRESENTING MY GLORIOUS OFFSPRING TO THE WORLD!"
His bellows echoed through the now fully awakened town, but were met with silence. A few unaccustomed monsters turned to stare incredulously in the skeletons' direction.
So began the day's outing. Gaster approached every Snowdin resident in sight to show off his son, raving about how adorable Sans was and how similar he looked to his father. There was no small amount of scientific gibberish thrown in. Most people agreed that Sans was cute, albeit unsettlingly unresponsive. Gaster assured them that he was just lazy. Nobody knew if it was the truth; nobody knew much of anything about Sans' origins. And so they merely smiled and nodded until Gaster left them alone.
When at last he had spoken to everyone in town, Gaster peeked at the basket to assess Sans' mental state. Much to his dismay, the little skeleton had exactly the same expression on his face. It seemed that social interactions would not be sufficiently stimulating.
No matter, thought Gaster. There are still plenty of hours left in the day. He walked out of town and crossed the rope bridge leading into the forest. "I'll get your attention yet, my little Sans," he said, and with one hand he stroked his tiny son's skull lovingly. Sans' smile widened a bit, and his eyesockets fluttered blissfully. Gaster chuckled in response and continued through the trees, the snow crunching beneath his feet.
Gaster knew what to do. He was a scientist. He could solve any problem; his brilliant mind would not be bested by the whims of an infant such as Sans. The answer to this conundrum was obvious: puzzles. Gaster himself could not resist a good puzzle, so surely it would provide ample stimulation for his son.
Luckily for Gaster, spikes were out of style. Sans was very fragile, as Gaster's attempts to raise his HP above one point had failed. The latest craze among puzzle makers was currently the classic ice puzzle. It would be the perfect way to get Sans to move and have some degree of amusement.
It didn't take long for Gaster to find a patch of ice with switches installed. He set down the basket and lifted out his precious bundle of bones, placing him on the ice tenderly. Sans sat on his belly with the same blank smile, utterly motionless. Gaster waited. His eyes were fixed on the baby skeleton before him, and a wide smile remained steady on his face. After a few moments, he reached out and slowly pushed Sans with one finger. His mandible softly scraped across the ice several inches and stopped. Gaster kept staring, smiling.
Sans still refused to show any signs of activity, physical or mental.
At laster, Gaster decided to do the work himself. He folded the little blue blanket and positioned it under Sans to prevent scraping. Then he pushed, gently at first, with enough force to slide the baby over the ice and onto a switch. Still not enough stimulation. With a gentle tug of magic, he jerked Sans across the ice at thrice the speed. He was starting to enjoy this. He propelled Sans in all directions at excessive speeds, and the baby never protested.
Gaster was growing tired of this. He had known the solution to the puzzle from the start, and he could only slide his infant son around it for so long. He used Sans to activate the switches in the right order to finish the puzzle. With a final motion of his hand, he pushed the baby over the full length of the frozen pond and into a snow drift, head-first.
"Wasn't that fun, Sans?" Gaster cried as he walked to where he last saw him. He dug his bony hands into the snow drift until he found the baby buried several feet in. He pulled him out and shook the powdery snow off to see if there was any change.
Sans' eyes still did not focus. Boy, was that little guy lazy.
Thoroughly frustrated by this development, Gaster carried his son back to the basket and laid him down in it. Then he realized that he had forgotten the blanket. He leaned in close and stared intensely at Sans for a moment, then spun around and hurried off to fetch his son's favorite blanket. It was covered in snow, but not nearly as deep in it as Sans had been. He shook it off and carried it back in a rush, for there was snow time to lose.
When he got back to the basket, something was different about it. He peered inside, his tiny white pupils searching with intense scrutiny. The basket was emptier somehow. Setting Sans to the side, he reached in and felt for the picnic lunch he had packed. Sure enough, it was gone.
"Sans," he said quietly, voice wavering a bit. "Did you eat all twenty-nine of those hot dogs?"
A low chuckle rose from beside the basket. Gaster turned to see Sans lying on his belly as usual, but with a wider grin. Then he sounded one clear syllable, in distinct Comic Sans, the first word he had ever spoken.
"Dunk."