A/N- Inspired by a lot of the fanfics I have read over the past day or so, please comment if you'd like to see more Undertale fanfiction!

They had made a nice life for themselves above ground. Just outside where the barrier had been, Toriel opened a school for monster children and human children alike. With the help of kind, local humans, they worked together to ensure it was up to the standards of the regional schools. The monsters that emerged from the Underground built a small town around the entrance, with tourism and trade establishing the town rather quickly.

All of Frisk's friends made a living doing what they did best, and Frisk was very excited to be living with Toriel again. Alphys and Undyne moved in next door, and took in Papyrus as a roommate. Toriel invited Sans to live with her, and he promised to help out around the house while she managed the school. The two of them had feelings for one another since they shared jokes through the door connecting the Ruins to Snowdin, but they took it slow with Toriel being so busy.

Frisk loved their new school, they were appointed as student ambassador to connect the humans and monsters within the school. It was hard at first, but all of the kids openly accepted one another quite easily. Toriel was the principal, and also did much administration work as far as curriculum and ordering supplies.

After a long Friday at school, Frisk came home to the smell of Sans's hot dogs cooked on the stove.

"Hi Sans!" They called from the living room.

"Hey kid! Once you are done with homework, we'll have dinner. Tori's not gonna be home until late, because of the staff meeting."

"I know," Frisk coughed. And then coughed a little bit more, trying to suppress it as much as possible.

Sans peeked his head into the living room, "you ok there, buddy?"

Frisk looked over at San, "I think so, it just feels like a bad tickle", they said. "Can I have some tea?"

Sans nodded. "Coming right up!"

Frisk cleared their throat a little and then took off their shoes and coat to get started on some history homework .Sans brought out some tea and hot dogs after a little while, and they fell asleep on the couch with the television quietly playing Mettaton reruns.

Late in the evening, Toriel arrived home from her meeting, and gently woke her loved ones to get them to bed. While helping Frisk up the stairs, she noticed they coughed a little bit, and frowned. She hoped they had not gotten sick at school.

She kissed Frisk goodnight with some tea on their nightstand, and then crept back downstairs to spend some time with Sans. "Thank you so much for taking care of Frisk, the meeting ran longer than we thought."

"It's no problem, there are leftovers in the fridge, they were dog-gone good!" He said, winking at her.

She smiled faintly, "That sounds perfect", and then paused for a moment. Is Frisk feeling all right? They were coughing when I brought them to bed."

Sans, nodding knowingly, replied with a sigh "I think they must be getting down with something, doesn't seem too serious though. I'll keep an eye socket out through the night."

Toriel held his hands, "what would I do without you?" She kissed his cheekbone and went to bed, yawning. Sans turned the TV off and checked his phone to see what his brother was up to. He felt bad for Papyrus being a bit of a third wheel for Undyne and Dr. Alphys, but the two of them said they didn't mind for now.

Sans awoke with a bit of a start, hearing a noise coming from the bathroom. He started closing his eyes when he heard something again, this time recognizing what it was.

He walked up to the bathroom door, "knock knock."

A child's voice weakly said "who's there?"

"Ash"

"Ash who?

"Hey kid, are you catching a cold?" Sans laughed at his own silly joke. He heard Frisk come to the door, looking very tired. "Doing okay?"

"Yeah," they said, rubbing their tired eyes, "that cough won't leave me alone."

"Take a warm shower, Toriel said that makes most anybody feel better. Maybe it'll wash away that cough" He paused, "Not my best joke, but you get the idea."

"Okay, I'll be out in a minute."

Sans tip-toed back to the couch, checking the clock as he drifted asleep, 1:50

Sans yawned awake to keep himself from falling asleep, but checked the clock again, 2:30 He looked over, and there was still a light on in the bathroom.

He went over and knocked on the door, without announcing it verbally, and heard a loud series of coughs. He checked the door handle; it was unlocked, so he looked inside. There he saw Frisk, in their clothes, sitting up against the wall next to the shower. "Uh, buddy?"

Frisk looked up, "I thought the steam might help, but it is a little hard to breathe. I was gonna open the window but I'm too tired"

Sans picked them up and carried Frisk to their room, tucking them in gently so as not to trigger more coughing, and quietly closed the bedroom door. As soon as he did, he heard more coughing, and a wheezing sound. He opened the door quickly to find Frisk gasping for breath. "Hey, woah, what happened?"

Frisk tried desperately to explain, but continued trying to inhale, choking on their sore throat. Toriel had jumped out of bed and was next to Sans in what seemed the blink of an eye. "Oh, my poor child! Sans, what can we do?"

Sans, panicking, tried to think. "Breathing, ummm, inhaler! Doesn't the doctor keep one in our bathroom for when she comes over?" Frisk nodded, coughed, and clenched their fists as they tried to force their lungs to open and let air in. Toriel placed her arms around Frisk to hold them upright, and Sans ran to the bathroom. He flung the mirror cabinet door open, and saw a box with the end of the inhaler sticking out. He brought it up and handed it to Frisk, without realizing any of them probably didn't know how to use it. Frisks instincts kicked in, remembering seeing Alphys use it before, and gasped openly and loudly, finally able to inhale and exhale without struggle. The two worried monsters at Frisk's bedside clung to them, hoping to hear that they were all right.

"That's… a little better." And a sigh of relief filled the room.

"What happened, my child? Why couldn't you breathe?"

Frisk, exhausted and shaken, slumped into her arms. She held them up as she grabbed another pillow to prop up the child. "My coughing got really bad, and I took a shower to see if it would help, but it just got really swelled and sore." Frisk paused, breathing heavily and trembling, "I had a big cough, and then I just couldn't inhale." A tear fell down from one of their eyes as their shut them tight. "Thank you, Sans, I didn't know what to do, I didn't know we had an inhaler here."

"Lucky we had it too…"

The weekend flew by. Frisk stayed in bed mostly, getting checked on by Toriel and Sans, and even Dr. Alphys came to visit. "I'm not a medical doctor, you know," to which Toriel nodded. "I know, but it's nice to have an outside opinion on the matter. Especially an academic one!"

Alphys blushed a little, and continued, "well, it is a good thing I left this inhaler here, I think it helped a lot. Don't use it too often, it stops helping if used too much too fast. It's also not powerful, since lizards don't need as much as humans, but I think it's a perfect dosage for Frisk, since they're a kid." She checked the counter on the back of the inhaler. "There is still plenty of juice in it too, but Frisk is usually pretty healthy, this is pretty unusual."

"What do you mean?" said Sans, who was walking in with tea for Alphys.

"Well, this sounds like it's probably bronchitis, from the way Frisk describes it, but it shouldn't get that bad, Frisk is a healthy kid. This must be a pretty bad case."

Toriel kissed Frisk's head, "we'll take good care of you sweetie."

Tuesday morning, Frisk was worse than before. Sleeping only 20 minutes at a time, their coughing became an exhausting nuisance. Frisk tried some medication that a medical human doctor provided, but it only helped a little. Sans came in when the coughing became particularly bad just to be safe. Frisk felt terrible, not wanting to cause too much concern.

"You're sick, it's why I'm here. You holler or cough, I'll come check on ya."

Frisk nodded, finally feeling comfortable enough to get some sleep.

Sans was thrilled when an hour passed with no coughing, even checking the bedroom for noise; only hearing breathing. Frisk had to be continuously sitting up, even when sleeping, and Sans felt bad it had been so hard for the kid to get some shut eye. He had finished some chores, and turned on the television for a little bit. About half way into the program, he heard a noise come from upstairs, and then Frisk's door opening violently. Frisk, nearly tripping down the stairs, coughing and choking, ran to the bathroom. Before Sans could say anything, he heard the child puke in the toilet, and then gasp for breath. Sans rushed in, and knelt down to try and help. It was another minute or so before the coughing subsided; Sans stayed with Frisk instead of getting the inhaler in fear of leaving the child alone. Frisk breathed audibly, seemingly gasping for every breath. Tears of exhaustion and pain flooded Frisk's eyes, pouring off their pale face. Sans wiped the remaining puke from the kid's chin, and wrapped them in a clean blanket from the closet.

"Let's get you to the couch, so you're closer to the bathroom." Frisk nodded and was lifted up and guided gingerly to the soft loveseat. Sans went upstairs to get the inhaler, and came back down to a very blank-faced patient on the couch. "I'm so tired Sans… I don't know how much more I can handle. It takes longer and longer to catch my breath… it feels like I'm drowning."

Sans sighed, "I'm not even sure what to do anymore. Nothing seems to be working to get you better. Maybe that doctor should increase your medicine."

Frisk, nodded, barely paying attention to what Sans had said. "Try to get some rest, I'll make soup." The child continued crying softly until the skeleton brought out the soup, a bowl for each of them. "It's still a little hot, give it a second."

A very course cough escaped Frisk's mouth, as they sat up a little more to have some soup. They took a bite, closed their eyes, and savored the taste. Sans had made the seasonings a little stronger so Frisk could taste it better. Frisk leaned their head to rest on Sans's shoulder, "Thank you", they said weakly.

Then, suddenly, Frisk sat upright, and twitched violently, blinking in sync with several more head twitches. Sans looked at them, as Frisk placed a hand on their head. Another twitch, and the hand scrunched into a fist, pulling on the hair a little, and then whacked their own head a couple times.

"Hey, what's…?" Sans's face dropped. Frisk's eyes flickered between their natural brown, a sickeningly vibrant red and complete black. "Uhhh… kid…?"

Soon, Frisk began coughing once more. Violently, their whole body convulsed with each enormous cough. They threw the blankets off and purposefully lunged for the floor as the coughing continued. Then, their eyes rolling backwards, their skin flushed nearly pure white and fell backwards onto the carpeted floor.

"Damnit, kid, wake up!" Sans yelled, reaching for the blanket and slid it under the kid's head as the child helplessly convulsed on the floor. After a few seconds, Frisk coughed violently, unable to breathe again, choked up out of their lungs a small black lump, and then fell over. Sans, immensely freaked out, picked up the small lump, it looked like a large, dusty seed. He put it in his pocket and looked down upon the kid, caught in a cold sweat barely holding on to breathing let alone consciousness. Sans picked them up, placing them on the couch while dialing Dr. Alphys, asking her to come immediately.

After about 10 minutes, a very defeated looking Sans answered the door to a nervous yellow lizard and her girlfriend.

"We came as soon as you called," Undyne explained.

Sans held the small black object up, and she took a step back. "That came out of their…" San nodded before she finished.

"That's… quite bad. How would that get in there?"

"What is it?" the skeleton asked, very insistently.

"Well it looks like a flower pod, but…"

Undyne and Sans glared at Alphys terrified, and then they all looked at Frisk who was sleeping very deeply on the couch.

"Gee, I haven't seen Frisk since Sunday, the bags under their eyes are so dark."

The three of them quietly passed through the living room to talk in the kitchen. "Have you told Toriel, yet?" Undyne asked.

Sans shook his head, "No," he exhaled deeply, "I'm afraid of what she'll say, she loves that kid more than her own self."

"If things get better progressively, I think we should wait and tell the both of them what happened in about a week," Alphys said. "I know that seems like a long time, but if Frisk knew I doubt they would rest easy."

They heard a small, startled gasp come from the living room, and then a very weak voice crying out "Sans?" A small sob, and then again, "Saaaaaans..?"

Sans came out, leaving the other two in the kitchen, "hey, you're awake." Looking into the small child's barely awake eyes. "What's up?"

"I…I'm so scared… what happened? Why do my muscles hurt?"

"You had a bad coughing spell and passed out." He tried to word it carefully, not wanting to lie but also reluctant to explain everything. "Alphys and Undyne and I were in the kitchen, want some company?"

"I want mom." There face scrunched up as they cried helplessly, sobbing at nearly a yelling volume.

"Shhhh, hey, I'll call her and have her come home. I know she'll come straight home for you."

Indeed she did, and in very little time Toriel returned home to find Sans with Frisk's faced buried in a pillow. "Oh, dear Frisk, what can I do?" She kneeled down next to the child, and was allowed to lift the pillow away from their face, burning with tears.

She slid herself on the loveseat and raised the child onto her lap, and the two of them hugged each other tightly. The three of them feel asleep on the couch.

Frisk awoke part way through the night, mostly out of habit from coughing upon waking up. They made sure to cover their adoptive mother with a blanket before going to the bathroom.

They flicked the light switch, and looked in the mirror. Dark circles starting to become bags under their eyes, pale as a ghost, and even their usually chubby cheeks had gotten thinner. They reached into the cabinet to take their overdue medication, and scooped some water from the faucet into their hand to wash it down. Taking a big sigh, Frisk turned the light back off, and started out of the bathroom, but jumped backwards when they saw Sans standing outside the door.

"Hey there, pal, feeling all right?"

Frisk, still catching their breath from having the crap scared out of them, nodded, and smiled faintly. "I'll be fine, although I doubt I will get back to sleep now."

Sans, stared down at the floor, feeling guilty, "sorry…"

Frisk shook their head, and leaned in to hug the skeleton. "This just means you gotta stay up with me!" They said, beaming. Sans was relieved, this was the happiest the kid had seemed in a long while, let alone since getting sick. Sans agreed, and they climbed the stairs carefully trying to avoid waking up Toriel.

Once they had gotten up to Frisk's room, the child climbed onto the bed and wrapped the remaining blanket around themself, like a large cloak.

Sans stood in the doorway, hesitating, trying to decide whether or not to mention the events of the previous day. Frisk looked over, their smile fading. "Sans…? What's wr-"

"Can you remember any of it?" San interrupted, looking the child completely deadpan. "Can you recall anything about that last coughing fit you had?"

Frisk was scared, and they weren't even sure why. "I remember coughing, falling to the floor, and then everything went dark." They stared down at their own hands, now fiddling with the folds of the blanket. "My lungs felt awful, and my head was spinning violently. Before I blacked out, I remember feeling like something was ripped out of me." Frisk looked up at Sans, too terrified to even let the tears welling up to escape the edges of their eyelids.

Sans walked over, hands in his pockets, and pulled out his phone with had a picture on the screen. "You coughed this up…" Frisk furrowed their brows, confused. "Alphys says it's a massive seed pod. She currently has it for testing, but said it's the reason you had been so ill."

Frisk covered their mouth, stifling a scream, just breathing heavily. They backed away from Sans, up against the wall while still sitting on the bed. "Hey, calm down kid, it's gone now, it won't hurt you anymore."

Frisk's panic spiraled, both sobbing and shaking in utter fear. "Don't let it…don't let them hurt me…"

"Them?"

"F-flowey… Asri-Ariel… th….them…" the child stuttered through their fear.

Sans crawled up onto the bed, kneeling next to the trembling kid. "Hey, we got you, they won't ever-"

"PLEASE… they'll kill everyone…I don't want to lose you, or anyone. They don't CARE, Sans, they will keep killing and destroying and.." their ranting fading as Sans held them close, letting Frisk's head bury into his blue hoodie.

"Shhhhhh…. They aren't going to reach you. It'll be fine…" Sans let his inner powers become visible, his left eye turned bright blue. "They'll have to get through me first."