Little Sister-an UNDERTALE Fan Fiction


A/N: oh gosh, I cannot believe I am doing this. Writing fics based off of a game! XD Never done it before, but it could be interesting. Plus, several others are doing it. I might as well, too.

Summary: on a walk in the snowy forest, slacking off as usual, Sans the skeleton stumbles upon something not so usual—a small skeleton child.

(My very first fic of this, so please be gentle if I do not get every single detail right. If you are not interested or don't like at all, then don't read)

UNDERTALE © Toby Fox Games

Red © Me


~Little Sister~

As usual, Sans slacked off at his job as a sentry. He was supposed to "always be on the lookout for humans," like his brother Papyrus constantly nagged him, but Sans wasn't as interested in capturing anybody like his brother. He just didn't care. Plus, he was too lazy. So, instead of searching for humans, he just walked through Snowdin's forest, whistling to himself or thinking up hilarious jokes to irritate Papyrus with. It was a regular thing. "LAZY BONES!" Papyrus would call him, but Sans had heard that remark time and time again. Everything was the same; he went out, slacked off, came home, Papyrus nagged him, then Sans went to sleep on the couch. Nothing special usually happened.

Except for this one, particular day.

Like always, instead of remaining at his post, Sans wandered off through the snowy forest, listening to the silence, whistling, and coming up with lame skeleton puns. He always walked the same path through the forest; there were times when his footsteps from yesterday's walk could still be visible, and he would step into them just for the heck of it. He looked up to the same dead, frost-bitten trees, stepped over the same fallen logs, and climbed over the same icy rocks. Despite everything being the same, it didn't really bother him. But of course, when something new appeared, if it ever did, it definitely piqued his interest.

Like always, when Sans turned a corner past a rock nestled between two trees, nothing would be there. Ever. However, on this day, something was different. He suddenly noticed another trail of footsteps parted from his usual track, exactly next to the rock and trees. Sans may have been a lazy jokester, but he was no fool. He knew that the new track of footprints was not his.

"What the…?" he murmured, kneeling down to examine them. "Too small to be Papyrus's," he clarified. "No one ventures this deep into the forest except me. Well, at least no one that I know. So who…?" He led his eyes along the trail of tiny footprints and soon saw they headed into a different part of the forest. Deeply interested and curious, he followed them.

Sans noticed that the further he followed this trail, the more spaced and messy the footsteps became. And not too long later, they started appearing like someone was dragged across the snow. He frowned, emanating a faint growl. "Now this is getting really weird…"

He decided to look ahead of the tracks and blinked at what he saw. At first, he thought it was just the shadow of a snow pile, but after staring at it long enough, he knew it wasn't what he thought. Racing over to the object, he stopped a few feet from it. Laying half-buried in the snow was a small skeleton!

"What the hell…?" Sans muttered and knelt down to examine the skeleton further. Shuffling some of the snow aside, he confirmed it was a girl, for the skeleton wore a faded pink dress and dirty red sweater, which glittered with frost. The skeleton girl's bones were heavily frost-bitten and cracked, like the winter was slowly eating at her and entombing her in a coffin of ice.

But the girl was not dead.

"She's still alive…" Sans said, baffled to see this kid still kicking in her condition. How he could tell—besides the fact that she wasn't a pile of dust—he didn't quite know. He could just…feel it. Was it perhaps because she, too, was a skeleton? He had no clue. He gently placed a hand on the fragile girl's shoulder and rubbed. "Hey, kid," he said softly. "You okay? You awake?" He received no reply.

Sans started worrying for the girl, and he didn't even know who she was, let alone how in the world she wound up there. But he could worry about that later. If this kid was still somehow alive, she needed to be taken care of, or she would end up freezing to death. He quickly dug up the rest of her body and carefully scooped her up.

Snow suddenly poured from the back of her skull, revealing a massive hole. Sans gasped at the sight of the severe injury. The entire parietal lobe was gone, and several tiny cracks sat around the edge. Staring at the wound, Sans let out a pitiful chuckle. "Wow," he said. "Someone sure did a number on ya, huh, kid?" He then started back for his and Papyrus's house. "But don't worry. You're in good hands."

Sans arrived home late that evening, and was greeted by the familiar smell of spaghetti coming from the kitchen.

"SANS!" Papyrus's voice came from the kitchen. "YOU ARE HOME EARLIER THAN USUAL! DOES THAT MEAN YOU HAVE FOUND A HUMAN?!"

Sans chuckled and replied, "Well, I found something, bro. Listen, I need your help, so get over here."

"WHAT IS IT?" Papyrus entered the living room, wearing his very cool apron, and gasped at what was resting in Sans's arms. "A SKELETON?"

"Yeah," Sans said and laid the skeleton girl on the couch. "Found her half-frozen to death in the forest, which is weird, 'cause I always walk that path and have never seen her before." He placed the girl in a comfortable position, then looked to his brother. "Okay, Papyrus, let's get every blanket we can find and mummify this kid."

"RIGHT!" Papyrus exclaimed and raced about the house, collected every blanket he first saw and delivered them to Sans, who wrapped them around the skeleton girl.

Once the girl was smothered with blankets, Sans's left eye glowed a fiery blue. He used his magic to gently heat up the blankets in order to thaw her out.

"YOU SAY YOU JUST FOUND HER IN THE WOODS?" Papyrus asked.

"Yep," Sans nodded.

"ANOTHER SKELETON," Papyrus muttered with fascination. "YOU DON'T SUPPOSE SHE COULD BE OUR LITTLE SISTER, DO YOU?"

"I dunno, bro. I don't remember having a little sister."

After a while, a tiny moan came from the girl, causing the brothers to sigh from relief. The girl shifted her head a little, revealing the massive gape she had.

Papyrus gasped. "S-SANS! HER HEAD!"

"I know, bro," Sans said and headed for the stairs.

"WHAT COULD HAVE HAPPENED? AND, WHERE ARE YOU GOING?"

"To get something," Sans replied, approaching his room.

"GET WHAT?" Papyrus asked. "WE SHOULD BOTH LOOK AFTER THE GIRL IN CASE SHE WAKES UP."

"You do it for me for a while, Pap. I gotta get something. Let me know when she wakes up, okay, bro?"

"SANS! GET BACK HERE THIS INSTANT!"

But nobody came.


She felt warm. That was all she could feel at the moment. Just comfortable warmth, and something soft. But for a minute, it troubled her. The last thing she remembered was the bitter cold of the icy snow, and then the next minute she was somewhere quiet and warm? It was confusing to her.

Well, it was almost quiet.

From somewhere nearby came the sound of snoring. Mustering the strength to open her eyes, she looked dizzily around. She saw she was in a second-story house, resting on a couch, unable to move due to being cocooned in numerous blankets. She heard the sound near her feet and saw a tall skeleton monster, fast asleep, snoring obnoxiously and muttering nonsense. At first, she pondered if she should feel afraid and cry out, but for some odd reason, she already trusted this monster. But she had never met him. Had she?

Still dizzy and aching, she let out another moan, louder this time, loud enough to awaken the skeleton. He yawned, stretched, scratched the back of his skull, and looked to her. Seeing her awake must have awoken him completely, for his bony face lit up like Christmas lights.

"OH, YOU ARE AWAKE AT LAST!" he cheered. The girl flinched at his cry for joy and shrunk under the blankets once more. Noticing her fear made the skeleton calm down and collect himself. "OH, I AM SORRY FOR STARTLING YOU," he said kindly. "YOU HAVE BEEN ASLEEP FOR A WHILE."

She tried moving but was tightly wrapped in the blankets. She wriggled about as much as she could and fretted; luckily, the skeleton understood her message.

"OH, IT MUST BE AWFULLY TIGHT FOR YOU," he said. "HERE, LET I, THE GREAT PAPYRUS, SET YOU FREE FROM YOUR TOMB OF BLANKETS!" He removed one blanket after another until she could move more easily. She struggled to sit up, so the skeleton named Papyrus gently helped her.

"W…Where am I…?" she asked once she found her voice.

"YOU ARE IN MY BROTHER AND I'S HOUSE," Papyrus replied. "OH, THAT REMINDS ME. SANS! COME DOWN HERE! SHE IS AWAKE!"

"S-Sans…?" the girl croaked.

"YES, HE IS MY SHORT, OLDER BROTHER. OH, THAT ALSO REMINDS ME! WHAT IS YOUR NAME?"

"M-My name?"

They both looked to the second floor when they heard a door open and shut. The girl saw a short, wide skeleton in a blue hoodie, white undershirt, black pants, and pink slippers hop lazily down the stairs with his hands tucked into his jacket pockets. He also wore a grin that seemed to be glued onto his face.

"THERE YOU ARE, SANS!" Papyrus scolded. "I WAS ALMOST ABOUT TO DRAG YOU OUT OF BED MYSELF! LOOK, SANS! SHE IS AWAKE!"

"Heh, yeah, I see that, bro," the skeleton named Sans chuckled. "And it only took her three days."

"T-Three…?!" she nearly cried out.

Sans laughed. "Ah, I'm just kidding with ya, kid. It's only been a day. No need to sweat. How ya doing? Feeling okay?"

The girl looked down at her lap and began to shyly tug at the blankets. "I…I guess so…" She couldn't bring herself to look at them.

Furrowing his brow bones, Sans looked to his brother. "Hey, Pap. Why not make her something to eat? She's probably hungry."

"YES! I WILL MAKE HER A FAMOUS BOWL OF MY FAMOUS SPAGHETTI!" Papyrus announced and fled to the kitchen.

When he left, Sans took his place on the couch next to the girl. "Someone sure had a bone to pick with you, eh, kid?" he said with a laugh. The girl didn't exactly know what he meant, but let out a laugh at his joke. Sans saw her confusion and sighed. "Okay, let's get serious for just a moment. What is it you last remember, kid?"

The girl shrugged. "I…I don't really know…I just remember walking…feeling cold…and then, I wake up here. I don't remember anything else."

"Well, do you at least know your own name?" Sans asked. The girl looked to him and shook her head no, her lip shaking like she was about to cry. "Okay, okay, kid, don't get upset," he told her. "You've been through enough."

"W-What do you mean…?" she asked him. Sans pointed to her head. She slowly reached up, but by the second her fingers touched her cheek bones, she looked bothered. She felt her face for a moment. Why was it so cold and hard? Then she looked at her bony hands. They began to tremble as she noticed she was nothing but bone and clothes. Shakily reaching for her head, she, too, became aware of the gaping hole in the back. Mortified of her discovery, she began to panic, as if she was trying to get away from herself. Sans immediately acted and got hold of her before she hurt herself.

"Take it easy, kid, take it easy," he said, holding her firmly in his lap. "It's okay." But the girl began to cry nonetheless. She clung to his hoodie and softly sobbed. He could see a tiny glow of green slide down her cheeks and drip into her dress. He sighed and rubbed her back, trying to calm her down.

"W…What am I…?"she wept.

"You're a monster," Sans answered, "like me and my brother. Specifically, a skeleton."

"H…H-Have I always…been a monster…?" she looked to him.

"I dunno, kid. I just found you half-buried in the snow and brought you here."

"You did…?" She blinked more green tears and then rested her head against his chest. "T-Thank you, Sans…"

Sans chuckled softly and smiled. "No problem, kiddo."

The girl sighed sadly. "But…it would at least make me feel better if I knew what my name was…"

Sans frowned in thought for a moment, then he snapped his fingers. "I think I've got something." He reached into his jacket pocket and pulled out a red winter cap, placing it onto the girl's head so it covered the gaping hole in the back of her skull. "How about we call you Red?"

"Red?" the girl repeated.

"Yeah, 'cause you got a red hat now. To be honest, I'm not so good with names, and this is the best I can come up with."

The girl tugged on the hat to have it sit more comfortably around her head, playing with the fuzzy ball on top for a few moments. "I like Red," she said with a smile.

Sans chuckled softly, noticing she was missing a tooth on the top left of her mouth. "Also here," he added, handing her some socks and a small pair of brown boots that used to belong to a younger Papyrus. "Wouldn't want your feet to stay cold forever, right?" Red smiled, a little sadder, and slowly slipped on the socks and boots. He also could see she was still upset and confused. Luckily, he knew how to try and cheer her up.

"Hey," he said. "You, uh, wanna know why skeletons can't cross roads?" Red blinked, awaiting his reply. "Because they don't have the GUTS to do it!"

Red stared at him for a moment. Then she started to giggle. "That's funny!"

Sans grinned; he had her hooked. "Hey, did ya know I used to be in a band? Yeah, I was quite good at playing the trom-BONE"—Red laughed more and more—"also on the xylo-BONE, too!"

He chuckled at how much Red was laughing; normally he received groans or a loud "SANS!" from his brother. He was pleased to have another audience who appreciated his witty humor.

He decided to continue. "But I had to quit, so I called the boss on the tele-BONE." Red let out a giggly squeal, cupping one hand over her mouth and the other around her side. "

Hey, I'm glad you find my jokes so…humerus!" Red hunched over, overcome with giggles. "But, tibia-nest, I'm not that good!" She started slapping her knee. "But it seems they really tickle your funny bone!" Red fell forward into Sans's lap and laughed and laughed. Sans couldn't help but laugh at just how silly the present situation was; here he was, with a girl who was nearly laughing her skull off at his jokes—HIS jokes—that most monsters would be annoyed; he kind of liked it.

"No more!" Red laughed. "I can't take much more!"

"Aw, do I really have to stop? I've got so many more good ones." Red looked up to him pleadingly through her giggles. "Ah, alright, I'll give ya a break."

Then, Papyrus entered with a plate of spaghetti. "HERE YOU ARE, CHILD!" he said proudly, "A WONDERFUL PLATE OF SPAGHETTI MADE MY THE WONDERFUL, GREAT PAPYRUS!"

"Eh, her name's Red now, Pap," Sans said.

"OH, REALLY?" Papyrus blinked. "WELL, HERE YOU GO, RED!"

Red was about to dig in when a thought suddenly came to mind. "How can I eat…if I don't have a stomach?"

Sans chuckled. "Just eat up, kid. Trust me."

"But won't it…fall right through?"

Sans winked. "Trust me."

Red blinked, wondering what he meant, and looked to her plate. She slowly ate, expecting something slippery to plop into her lap and soil her dress. But nothing came. Amazed, she resumed eating until the plate was clean.

Papyrus was ecstatic, pleased to see someone who actually liked his spaghetti enough to finish the entire plate. "I SHALL MAKE YOU SOME MORE!" he said, took the plate, and raced back into the kitchen.

Red licked some spaghetti sauce off her fingers and looked to Sans. "How was I able to eat if I don't have a tummy?"

Sans grinned and leaned in close, like he was telling her a secret. "Well, ya see kid. We monsters, we're made of magic."

"Magic?" Red asked, her eyes glittering. "Really, magic?"

"Yep. Wanna see some?" he asked. Red nodded eagerly, clapping her hands. Sans chuckled and his left eye glowed. "Alright, then. Hold onto your hat." His left hand emanated a soft, blue hue and rose up. Red suddenly realized she rose up into the air too and floated around. Excited, she exclaimed in awe and giggled loudly.

"This is amazing!" she squealed. "I'm flying!"

"Well, more like floating," Sans said. "But I could probably make you fly. If you ask nicely."

Red giggled. "I wanna fly! Please, please!"

"Well, that ain't a question, but I'll let it slide." Sans swirled and gave his wrist a flick, sending Red soaring across the room—and straight for the kitchen. "Uh-oh…"

"WHEEEEE~!" Red cheered as she flew. Then came a loud crashing sound. Sans rushed to the kitchen and saw spaghetti sprawled all over the floor, and all over Red and Papyrus.

"Let's go again!" Red laughed.

"MY SPAGHETTI!" Papyrus cried out.

Sans chuckled nervously. "Whoops. Sorry, Pap. I'll help ya with that." His left eye and hand glowed blue once more, and all of the spilled spaghetti rose from the floor and off of the messy skeletons. "I was just showing Red some magic, bro."

"WELL, PERHAPS A BETTER PLACE WOULD BE OUTSIDE?" Papyrus huffed. "AND WHAT WAS ALL THAT NOISE?"

"Oh, I was also telling Red some of my amazing jokes," Sans said.

"OH, BROTHER…"

"But she seems to really like my…SANS of humor!"

"SANS!"

Red hugged her belly and fell onto her back with laughter. She then leapt to her feet and looked up to Sans. "Sans! If what you say is true, and if I am a monster…does that mean I have magic, too?"

"I'm sure it does," Sans answered.

"Cool! But…" Red looked to her hands. "H…How do I do it?"

"Well," Sans began, noticing Red beginning to look tired again, "I'll fill ya in about it tomorrow morning. Okay, kid?"

Red yawned, rubbing her eye sockets. "Okay…" She was led back onto the couch and bundled under some blankets. Once she was settled, she looked up to the brothers.

"Sleep tight, kid," said Sans.

"PLEASANT DREAMS," said Papyrus.

Red shifted to their direction a little. "W-Wait…H-How long am I allowed to stay here?" she asked softly.

Sans and Papyrus exchanged glances, as if they needed to look at each other to agree on an answer, and then looked back to Red. "Well, as long as you want, kiddo," Sans told her. "I mean, you'll have to rest on the couch until we can find ya a proper bed. Where else are ya gonna go?"

"You'd really let me stay here forever? W-Won't I be a bother after a while?"

"NONSENSE!" Papyrus chortled. "WE HAVE ONLY KNOWN YOU FOR THIS LONG AND WE ALREADY THINK OF YOU AS A LITTLE SISTER!"

"You do?"

"OF COURSE! RIGHT, SANS?"

Sans only chuckled as his answer, then reached down and tousled Red's forehead. "Night, Red," he spoke softly, and the two brothers headed up the stairs.

"SANS! I WANT A BEDTIME STORY TONIGHT!" Papyrus's voice rang from behind his bedroom door. "THE ONE ABOUT THE FLUFFY BUNNY!"

"Alright, alright, Papyrus. Now get into bed," came Sans's voice.

Red sighed and played with the trim of the blankets. How could they give her permission to stay with them, just like that? She was a total stranger. She didn't know them and they didn't know her.

Suddenly unable to rest, she got up from the couch, crept up the stairs, and peeked into Papyrus's room, where the two brothers nestled into a racecar-shaped bed and Sans read his tall, younger brother a story. She smiled a little at how they cuddled up to each other, like they were all the other had in the whole world. Red could see that Sans took good care of Papyrus; she also saw that being the oldest, he had to work the hardest, even though he had a sort of lethargic appearance. The thought of Sans pushing himself to more effort because of another house guest saddened her. With only the two of them to look out for each other, it wouldn't seem right to throw in a stranger like her.

With a sigh, Red parted from the crack in the door, and sluggishly headed downstairs.


"SANS! SANS!"

Papyrus's frantic shouts pulled Sans from deep sleep. With a groan and a yawn, he sat up in bed, stretched, slipped on his slippers, put on his hoodie, and headed downstairs, the sleep still not quite lifted from his eye sockets. "What is it, Papyrus…?"

"SANS! RED IS GONE!"

"What…?" Sans headed for the couch and indeed saw it was empty. Nothing but crumpled blankets and a note sitting on the pillow. He picked it up and read it.

"Dear Sans and Papyrus,

By the time you read this, I will be somewhere else than on this couch. Thank you so much for your hospitality. I wouldn't be alive if it wasn't for your generosity. Thank you for giving me someplace warm to sleep, good food to eat, and making me feel better. And I also greatly appreciated the offer to stay with you guys forever.

But I just can't.

It just doesn't seem right. As much as I loved being with you, I just can't stay. I don't want to burden you guys with another mouth to feed. You both work hard enough to take care of each other. I don't know if I will see you guys again, but I will never forget you.

Papyrus, thank you for the spaghetti. It was very delicious.

And Sans…thank you for the hat and name.

Sincerely,

Red.

"Kid, you gotta be kidding me…" Sans grunted and tossed the note aside as he headed for the door.

"WAIT, SANS! WHAT DID IT SAY?!" Papyrus called after him; when he didn't answer, he picked up the note and read it, sadness slowly edging onto his face as he read word for word.

Sans raced outside, hoping he could follow Red's tracks just like how he found her, but it was snowing heavily outside, so any sort of trail Red had made would be already covered by snow. In other words, Sans had no idea where to start looking.

Red slowly trudged through the ankle-deep snow, hugging herself tightly as she ventured blindly through the forest to seek shelter from the heavy snowfall. She often glanced behind her and saw her tracks slowly being refilled by the snow, like they were never there, and then kept going. Each time she looked back, she thought of Sans and Papyrus. She wondered if they had found her note by now, if they were deciding on going after her. She wondered if they would meet again, and if they did, if they would persuade her to come home with them. It didn't matter. Even if she wanted to, she wouldn't go back home with them. They were nice hosts, but she didn't want to be a burden to those guys.

But she couldn't help but wonder if she would find anyone as kind and hospitable as them, and her eye sockets started to flood with tears.

WE HAVE ONLY KNOWN YOU FOR THIS LONG AND ALREADY THINK OF YOU AS A LITTLE SISTER…

Won't I be a bother?

Where else are ya gonna go?

I don't want to be a burden…

NONSENSE!

Red blinked tears and sniffled softly, clutching herself. Part of her told her to turn around, the other forced her to press onward, but with each step she took, the more she longed for the warm, cozy couch she first woke upon. She had wandered so dazedly and absentmindedly through the forest that she hadn't realized she had come to a clearing in the forest where the snow didn't fall.

"Howdy!"

Red was startled by the sudden new voice. She looked around but saw no one. Starting to shiver, she swallowed and called back, her voice wavering, "H-Hello…?"

"Over here, kid!"

Red looked to the voice to see something in the clearing. It appeared to be a golden flower with a smiling face. "W-Who are you…?" she asked.

The flower grinned and replied, "Don't be scared of me, kid. My name is Flowey. Flowey the flower!"


~End of Part One~