Core Issues
by Nicolle

Disclaimer: Undertale is the creation of Toby Fox. Gaster!Sans, our lovely narrator, is the the creation of Borurou. This story is copyrighted to me.

1. This story references Underfell, but only really hits heavily on Technotale which is my AU. The basics for Technotale can be found here: baaikha. tumblr post/ 135260973145/ undertale-au-technotale. If you are inspired to do so, run with it!

2. This story is rated T for language, suggestive jokes/themes, and a some nightmare fuel at the end.

Episode One: Core Issues
(Bones, the Sans of this world, is our narrator!)

A vibration on my sternum jolted me awake. I looked at my phone for a second before shoving it in my pocket.

"Dammit, Blue. It's three in the morning."

Sitting up, I looked around for a bottle of Red Hot sauce, found one, and discovered it was empty.

"Great."

I'd fallen asleep on the couch in the Seraph Foundation's communal living room. Again. Paps would complain about it come morning. Provided I was still around. I hadn't looked at the message, but Blue never contacted us unless it was a mission. I stumbled to my feet and headed down the dark hallway.

There was a light on in the lab, and a quick peek revealed Asriel at work on some project or other. I was never really sure what the goat prince was up to half the time since his specialty was biomedical engineering. Medicine was not my forte. Time and space distortion? That's my bae.

A red glow beckoned me down the hall to Frisk's office. It blinked out suddenly when I got to the door. Frisk murmured ascent into her phone as she wrote. She turned and looked at me. I waved the empty bottle at her.

She put down her phone. "Asriel bought an entire flat of Cholula sauce for you. It's in the kitchen."

"Where is Blue sending us now?"

She smiled.

"What?"

Frisk pulled her hair back in a braid. "It's funny how you all call him 'Blue.' Not 'Prime' or 'Alpha.' As if for some reason his use of blue magic is unique to him."

"It's the hoodie."

"That makes even less sense. You all wear hoodies."

I snorted. "This, sweetheart, is a fur lined, leather bomber jacket. And you are wearing an exact replica."

"Yeah. But it looks better on me."

I pulled the note out of her hands. "I own this look." I glanced at the equations in Frisk's neat script and resisted the urge to solve them. "Any details?"

She shook her head. "Just that the Fase Real Intelligence System Kore isolated it as an anomaly."

I grimaced. "Her."

"What?"

"Of all the Frisk's, she's the one that scares me the most."

"Why?"

I changed the subject. "Standard op, then?"

Thankfully, Frisk didn't force the subject. "As soon as I gear up, yeah."

Her legs were unsteady as she rose and I grabbed her arm. "Woah there, Babe. Maybe you should get some sleep first. Why were you up this late?"

Frisk shook herself a little and headed for the equipment room. "Asriel wanted to check all the wires and chips in my head."

I followed her down the hall. "So why did you let him do that to you?"

"You know I didn't have a choice. I was unconscious and dying at the time." She opened the door to the armory and grabbed her equipment bag from a nearby shelf.

"I meant, why do you let him take all night? Or is giving you a check up code for 'snu-snu?'"

She dropped her jacket on a bench and changed into her armor reinforced uniform. "I am not letting you watch Futurama anymore."

I leaned against the door, giving her my best, lecherous smile. "So, no 'Netflix and Chill' this weekend?"

She picked up her jacket and put it back on. "I'm going to pound you into the floor now."

"Bow chicka bow wow!" I jumped out of her reach just fast enough to trip over the skull of a GB. It looked up at me mournfully, worried I was angry. I rubbed it's boney snout reassuringly. It looked up at Frisk, who patted it on the nose before she pulled up her collar to cover her neck.

"Off the floor, Bones. I want to be done so I can get back to writing my tell all book."

I stood and dusted off my jeans. "Does it have pictures of me in compromising positions?"

"No."

I opened my mouth to deliver a zinger.

"Just your brother."

I sighed. "Yeah right." I put my right arm around her waist. Lifting my left hand, I turned it so instead of seeing through the hole, I was gazing into my own, very personal, rift in space. I started solving the equations. The darkness in that space parted.

We landed in a snowy forest away from the path to Snowdin. The GB squeaked and rolled around in the snow. Frisk looked toward town.

I followed her gaze. "That's a lot of smoke."

"That's smog." She pulled out her mask and put it on.

Staying off the path we trudged through the woods. When we got close to Snowdin, I climbed a tree to have a look at the town and wished I hadn't. "The town is caked in filth."

"So it's like your bedroom?"

"Nah. I would never let my guitar collection get dirty." I looked around. "I don't see anyone, but there are lit windows."

"What about your place?"

I flinched a little. I really didn't like it when anyone referred to a different Sans-es' things as my own. But it was never a discussion I wanted to have either. I squinted. "Dark."

"Let's check it out."

We skulked into town behind the line of houses. I pulled out my keys and tried the lock on this world's version of my old laboratory. The lock didn't even turn. I pulled out my lock picks and went to work while Frisk and the GB kept a look out. The door popped open after a couple seconds. I flipped on the light and looked around. The lab was cleaned out. The time machine, the blue prints, everything was gone.

Frisk's head popped in the door. "The house is empty and nothing is out of place. It looks like it's been empty for a while."

I stepped outside and pulled the door shut. "The lab's cleaned out."

Even behind the mask, I could see her frown. "I don't know why there's so much smog. There aren't any factories that I can see."

"Let's move on to Waterfall and check out Undyne's place."

An hour later we stood in front of the wreckage that was Undyne's house. I've seen her place burned down, flooded, used for target practice, and shaken apart by a super loud music lesson. But this, I couldn't make heads or tails of what I was looking at. Frisk started digging through the wreckage and I stood back, waiting. The last time I tried to help when she was investigating had not gone well.

"Bones? Can you move this wall over there?" She pointed to a large section that had fallen on the open living space. My eye flared to life and I gently set the wall aside, revealing the mess that had been Undyne's living room and kitchen.

Frisk jumped over a pile of debris and started digging around the floor. "Big fight. Three people. By the foot prints, it was Sans and Undyne going at it." She gently lifted a sneaker. "This Frisk is either a very tall child or a pre-teen. It looks like Undyne was protecting her." She pointed to the wall I had moved. "Those are GB blast marks, but they aren't whole. Meaning Undyne really took it in the face." Something caught her eye and she threaded her way back toward Undyne's bedroom. She picked up a long red scarf and shook off the dust before pulling down her mask and putting it to her nose.

"Did this Frisk kill Paps?"

"No. It doesn't smell like you. It smells like teen girl."

"Are you implying that I smell bad?"

She raised an eyebrow. "You don't. But some Sans-es have the odour-du-lazy in massive amounts." She tossed the scarf to me. "Stow that somewhere safe. We need to get to the Lab and watch Alphys tapes."

"Hotland's quite a ways," I mused.

"You want to portal? It might tip off this world's Sans. It will definitely tip off this world's Flowey."

"Based on what you see here, could you take Sans in a fight?"

Frisk's smile grew wide and she giggled as she put her mask back in place.

I rolled my eyes. "We'll portal. I don't know why, but I'm not really all that worried about Flowey."

Frisk hopped over the debris, hooked a finger in the GB's snout, and took my hand. The world went black in a swirl and when color came back, we were standing outside the back entrance of the Lab. Frisk put her ear to the door before opening it. The lights were out, but the machinery was running. There was movement under the desk.

"Alphys?" Frisk called.

"Don't hurt me!" came the pained response.

I flicked on the lights and Alphys screamed.

Frisk knelt down next to the desk. "It's okay. We aren't here to hurt you, Alphys. We came to help."

The lizard woman turned her head slowly and looked at Frisk. Alphys reached up and pulled down the breathing mask covering Frisk's nose and mouth. "Frisk?"

My Frisk nodded with a warm smile.

"How?"

"I'm not your Frisk. We're from a different universe."

"We?" Alphys craned her neck to look up at me. I smiled and gave her a half-hearted salute. She blinked a few times, very rapidly. "You're Sans?"

I cocked my head toward Frisk. "Her Sans. Most people call me 'Bones.'"

"Alphys?" Frisk asked, "Can you tell us what's going on?"

She looked back and forth between the two of us very quickly before putting her head in her hands. "I don't know what's happening!" She suddenly grabbed a hold of Frisk's arms, and a thrum went up my spine. "I was at a beach resort with Undyne! She and Frisk had fallen asleep on the couch while watching a movie, and the next thing I know I'm back in the Lab watching a video feed of Frisk in the forest outside of Snowdin!"

"You were on the surface?" I asked.

Alphys nodded.

"May we watch the tapes from your video feed?"

She shook her head and started weeping. "You don't want to see those!"

Frisk petted Alphys scaly head and cooed to calm her. My impatience rose quickly. I resisted the urge to tap my foot.

Frisk pulled the lizard woman out from under the desk and took her over to the dark monitor. "Show us the tapes."

She nodded and shakily turned on the monitor. After a few button pushes, the video started and Alphys hurried away from the screen, sitting on the floor with her back to it, covering her ears.

The video cut in just as a pre-teen Frisk burst through the door of the Ruins. She was covered in a fine dust and running in shear terror while looking backwards at something. She tripped over a fallen tree branch and lay there in the snow, weeping profusely. When she finally stood, it seemed mechanical in nature, like she was fighting her own body. She stumbled to the nearest tree and started banging her head against it repeatedly and violently.

The video cut out and picked up with the girl sitting on her heels in front of Papyrus. He assured her that everything was alright and whatever was happening could be fixed. And then his skull fell into her lap. She screamed and I looked away so I wouldn't watch Paps turn to dust. When I looked back, I saw a Sans who looked exactly like Blue but was filled with so much rage that his eye had activated on it's own. The girl grabbed Papyrus' scarf and ran.

"Oh, kid. That never works," I whispered.

Frisk glanced at me for a second before a scream glued her back to the screen. The video cut in several places, following the girl as she did everything in her power to evade Sans as he teleported ahead and around her. When her terror peaked, she ran into Undyne, who grabbed her, and they both disappeared into the river.

The video picked up with, as Frisk had predicted, Undyne protecting the girl in the rubble of the house before a flying bone hit it's mark. Undyne fell to her knees, smiling at the girl as her body faded to dust. Sans grabbed the girl by the arm, ripped Pap's scarf from her neck, and ported away. The video feed died as the side wall of the house crashed down, scattering Undyne's dust across the area and leaving the wreckage we found earlier.

Frisk looked at me. "Where would you have gone?"

I rubbed the back of my head and stared at the ceiling. "I would have taken the equipment from my lab and gone to the Core to try hooking Frisk into the Time Machine to see if I could get it to work off the power of her Determination." I folded my arms over my chest. "It won't work though."

Frisk cocked her head to the side. "Why not?"

"Because the Time Machine is incapable of working."

"But we also haven't seen any Sans who looked so willing to just off their Frisk either. Not even Red."

"He still killed her several times before he gave in."

Frisk sighed. "Let's get to the Core." She took a step toward the door and stumbled with a groan.

I caught her before she hit the floor and switched her weight onto my shoulder.

Alphys jumped up. "Is Frisk alright?!"

I frowned and picked her up bridal style. "C? What's going on?"

A red glow burst to life on Frisk's shoulder and a small hologram of Chara Dreemurr looked up at me. "She's okay. Just asleep. She hasn't slept in 48 hours."

I rolled my eyes. "Great."

"She likes to tell herself that she did this all the time back in the day. And increasingly forgets that she doesn't have as much practice doing it now a days. She's also neglected to eat in the last twelve hours."

"So high maintenance."

Alphys stared in wonder. "A hologram!"

C turned to Alphys. "Hello, Dr. Alphys. I am C, the artificial intelligence based off the memories of Chara Dreemurr, the adopted human child of Toriel and Asgore. Asriel made me shortly after Chara's death and implanted me into Frisk when she fell into the Underground."

Alphys blinked a few times and looked at me. "That's not the story as I know it."

I shrugged. "It's different from universe to universe. Got a bed I can put her in?"

"Oh yeah! There are plenty of beds below." She opened the door to the elevator and took us into the True Lab.

I slipped Frisk's pack off of her back and put her on a bed. As gently as I could, I moved her hands to clasp over her stomach. I must have been watching her sleep for a while because Alphys coughed nervously behind me.

I turned and smiled, scratching the back of my head. "Sorry! Spaced out there."

Alphys grabbed my hand and adjusted her glasses while looking at it. "You are nothing like the Sans I know."

I straightened up and took my hand back. "Not in the least." I sat down on the bed so I would be eye level with her. "What do you want to know? Ask away."

She looked at my Frisk and back to me. "How does she have such a high LV and still be so caring?"

"Yeah. It's pretty up there, huh?" I smiled and looked up, remembering. "Frisk was an adult when she fell. She's former military, but if you ask her about it, she'll dodge any questions about what her service entailed. She's genuinely sweet and caring with a high tolerance for bullshit. But when she's made up her mind that something must be done, there is very little that can stop her."

Alphys frowned. "What's your story?"

I eyed her for a moment and sighed. "The Sans and Papyrus you know are the sons of your predecessor, W.D. Gaster. Me and my Papyrus are W.D. Gaster. When he fell in the Core, he split into two beings. We both exist as two halves of the same whole that have become, over time, completely distinct and separate individuals." I held up my right hand, staring at the hole. "I remember all of the research, but I have none of the drive to pursue it. Papyrus remembers nothing but has all of our collective drive and enthusiasm." I smiled wryly, hand falling to my jacket pocket. I had worked so hard for so long to put us back into one piece that I hadn't realized we'd become two different people until Frisk had pointed it out.

"You mentioned a Time Machine. I didn't know Sans had a Time Machine."

"Every Sans has a time machine. Each and everyone of us builds it in the hopes of returning to the past and fixing it. It never works."

"You're awfully free with the information," she observed.

I gave her a wry smile. "You won't remember it after reset."

Alphys eyes narrowed and she wiggled her nose. "What is your universe's history?"

"Chara Dreemurr was the first human to fall. He was a good and happy child. He loved his family very dearly and hoped one day to find a way to bring down the barrier. He died after a long battle with cancer. Toriel absorbed his soul and passed through the barrier in order to take him home. She was attacked by the humans there, but did not retaliate. She held on long enough to lay Chara to rest among the flowers he loved so much and came back through the barrier to die on throne room floor.

Alphys covered her mouth with her hands. "Your Tori is dead?"

I nodded. "Asgore declared war on humanity and Asriel took his mother's dust and left, going to live in the Ruins. The story from there is very similar to your own. Six human children fall and attempt to make it through the Underground, dying along the way. And then Frisk fell."

I sighed. "Like I said before, Frisk was an adult when she fell and the fall nearly killed her. Asriel found her. He'd repaired the damage but her high LV prompted him to include his own measure of insurance against harm. He wasn't going to let her die, but he wasn't going to let her hurt anyone else, so he installed C into her head. He told me later that he was rather gratified to find that her LV was not an indication of her willingness to hurt others. She'd gone up Mt. Ebott to investigate reports of missing children for her employer.

"When I first saw her, I panicked. I'd never seen LV that high before in anyone. I warned Paps to stay away from her. But, he went to capture her for Undyne anyway. When I caught up to them, I found her laughing so hard she was literally rolling on the ground. After Paps spared her, I asked her why she didn't kill him. And she looked at me like I had grown a second head. She said, 'Why on earth would I do such a thing? Your brother is the biggest Cinnamon Roll I've ever met!'"

Alphys giggled. "Hey, you want something to drink? I've got ketchup."

I leaned back and put my hands behind my head. "I'm a hot sauce kind of guy."

Alphys stood. "I've got a bottle of that. Undyne liked to use it for..." She trailed off and started crying.

I stood and hugged her. "It's okay. We can figure out what's wrong and set everything right. You won't even remember any of this ever happened. It will disappear like a bad dream and you'll be back at the beach soaking up some sun with Undyne and Frisk before you know it."

Alphys sniffed. "You mean it?"

I nodded. "We've gotten pretty good at fixing these kinds of things."

"I'll go get that hot sauce." She headed off, tears still in her eyes.

I sat down on the bed across from Frisk's and put my feet up. The GB landed on my lap and snuggled in, the light in its eyes fading to a dull glow. I figured a few winks wouldn't kill me and fell asleep.

I woke to a hard and painful crack from being thrown into a wall. I bit back a scream and looked for the idiot who needed to have a bad time. Dread consumed me when I realized I wasn't in the True Lab. I was in the lowest basement level of the Core. I saw the back of Sans blue hoodie as the door shut and the lock clicked. Alphys was cowering in a corner.

"I'm so sorry! He... He said he wouldn't hurt Mettaton if I turned you over to him!" She curled in a ball and sobbed in the corner.

"Oh Alphys," I said, feeling the rift opening inside of me. "You're not as sorry as you're going to be." The power of the Core crawled through every part of my being.

xxx

A female lizard monster stared at me with undisguised horror. Fascinating! She looked like an assistant, but not one I recognized. Never the less, my office was a complete mess. Files were every where like someone had thrown a fit in the room. Very unbecoming.

"Assistant, why is my office in shambles?"

The lizard woman shook her head like she didn't understand what I had said. Ah, she was new then. Understandable. A light sparked in her eyes and she grabbed my hand.

"Dr. Gaster! There's an intruder in the Core! He's hooked a human child up to a machine in the energy unit!"

I smelled a lie, but it did explain the mess. A human child? The only human child in the Underground was Prince Chara. I grabbed her arm. "Come with me."

There was a crackling hiss from my collar. I was wearing the most unusual jacket. I quite liked it, though it wasn't very practical for my work.

A voice came through. "Bones! Where are you?"

A thrum went up my spine. A very pleasurable sensation. Dark and warm. Who owned this voice?

The lizard woman stood on her tip toes to speak into the tiny receiver. "Bones isn't here right now."

"Great. Just great. Every time we go to the Core basement," the voice huffed.

"Who is this?" I asked.

"Your favorite test subject."

Oh? She understood me! Very interesting.

"Listen, Dr. Gaster, there's a short skeleton monster in a blue hoodie in the Core. He's hooked a young girl and myself into a broken time machine in the energy unit. I can get the both of us out, but I can't counter act the skeleton's blue magic if he comes back. So the faster you get over here, the sooner we can get this mess cleaned up, and back to your experiments."

"We shall be there shortly."

Disabling the door lock, I strode out the office, the assistant on my heels. We reached the energy unit without running into the intruder. An adult human woman was helping an injured human girl out of a machine she'd been hooked into. I knew, without understanding why, that the woman was the owner of the voice that I found so... enjoyable. She was wearing the same curious jacket that I was wearing. I found that uniquely satisfying. She held the girl in her arms gently, like a mother holding a child. The scene was pleasing in a distinct way. When she turned toward me, I reached out and touched her face, and she accepted my touch as if it were a completely normal gesture. She smiled warmly at me, and passed the girl into my arms.

Lightning quick, she grabbed the assistant by the throat and lifted her with one hand. An intensely strong female. Very well trained. Expression quite terrifying. Such a seemingly large contradiction from just a moment ago.

"C? You have 30 seconds to explain to me why I shouldn't beat the crap out of Alphys. I know I passed out on my own from exhaustion, but that doesn't explain why I'm now in the Core."

A red hologram flared to life on her shoulder taking the shape of Prince Chara. Very interesting.

"When Alphys went to find hot sauce for Bones, she ran into her Sans. Who threatened to kill Mettaton if the two of you weren't turned over."

She dropped the lizard woman, Alphys was it?, to the floor.

"So typical. I was worried that portal would cost us and it seems it has." She groaned and rubbed her forehead. "Just find my equipment bag."

Alphys ran off. The woman turned to me and smiled at the girl in my arms. She pushed the girl's hair from her face and the resemblance was uncanny. "This is you? No," I corrected, "This is a version of you."

She looked at me. "Correct, Doctor."

I shifted the girl to one arm and took the woman's hand in mine. "You said you were my favorite test subject, but I don't remember such a fascinating individual. If you would be so kind as to relieve me of my confusion, I would be very happy to explore how you would be a... favorite of mine." I lifted her hand to my face, nuzzling her fingers.

The hologram Prince Chara thew his hands up in the air. "Why does he always hit on you when he's like this?!"

The woman sighed and the warm smile she gave me made my knees a bit weak. So very interesting that a complete stranger had this effect on me. Then again, I had never been anything but entirely honest and forward with my feelings. I would make for a poor scientist if I were not.

"Because he isn't afraid of my rejection like this." She pulled her hand from mine slowly, letting the tips of her fingers gently graze my chin. "I'm Frisk, and the way you are now, we haven't met yet. Well... Not in this universe. You seem only able to remember me in our own timeline and not in another."

"The way I am now? An interesting way to phrase it, don't you think? I can tell that I am not exactly myself. I am too short. I am dressed inappropriately for lab work of any kind. A strange person is using my greatest creation for his own purposes. And I am rather... inspired by the presence of human woman that I have no memory of. But instinct tells me that I should simply follow your lead. Tell me more about this girl."

"She is a version of me. She's the key to breaking the Barrier and she desperately needs our help."

"Can she really break the Barrier?"

"She already has, but something has gone wrong. When she comes around, I'll be able to find out what happened to get her in so much trouble."

Alphys came back in the room with a back pack. "I found it, but it looks like Sans was digging through it."

Frisk nodded and looked through the bag. "Not surprising." She emptied an unusual array of things from the bag. Finding smelling salts and a piece of Monster Candy, she revived the girl and fed her the candy.

"Hostile coming down the hallway," the hologram said.

"Of course." Frisk shoved everything back into the bag.

"He took your gun," the hologram said.

"It was loaded with hard foam and I doubt he'd use it, so, no worries. I keep the dissolvent in my coat pocket." She looked to me. "Will you carry her, please? We need to leave."

I nodded once.

"Thank you." Frisk shouldered the bag. "Alphys, get on the right side of the door, Doctor, on the left. Let Sans come in right past both of you and exit. I'll keep him busy while you two get her out of here."

"Where do you want us to go?" I asked.

"Snowdin."

Alphys looked between Frisk and I. "Will he be all right?"

"As soon as you leave the Core, yes."

So if I leave the Core, my confusion would abate. Why was that?

"Hostile at door," the hologram said. "You have ten, Frisk."

"Ready."

My questions would have to wait. The safety of the girl in my arms being the primary concern. Blue light encased the door. It crumpled and ripped from its hinges. Frisk darted forward, incredibly fast, and grabbed the small skeleton monster by the arm. In the blink of an eye, he was flying through the air across the room. Holding the girl tightly, I ran, Alphys on my heels. When we came to the elevator at the end of the hall way, I grabbed the lizard woman by the collar and pulled her into the emergency stairs. With a burst of blue magic, I had us at to ground level. We stepped out of the Core.

xxx

I stopped dead and nearly fell. A pre-teen Frisk in bad shape was clinging to me for dear life. I looked back at the Core.

Alphys grabbed my sleeve. "Come on! We have to get to Snowdin!"

I followed Alphys to Hotland and we hitched a ride on the Riverperson's boat to Snowdin. We ran for the house and stopped dead when we saw lights on inside. I peeked in a side window and saw Frisk sitting on the couch, eating a plate of spaghetti, while Sans lay in a heap on the floor.

"How did she..." Alphys trailed off.

"I have no idea how she does that." I opened the door and went in. The Frisk in my arms whimpered against me. "Hey. It's okay. Promise."

"Sketties are in the kitchen," Frisk said between bites. She toed Sans. "You want any big guy?" He didn't move. "Nah. I didn't think so." She slurped a noodle.

"Is he okay?" the Frisk in my arms whispered. She pushed out of my arms and fell, crawling to get to him.

"He's fine. Just unconscious. Sit down and eat. We need to know what happened so we can fix it."

The girl sat down next to Sans and gently touched his head. I sat down next to Frisk.

"Feeling better?" she asked.

"How bad was it this time?"

"You were quite helpful."

"Did I do anything embarrassing?"

"Embarrassing? You never do anything embarrassing."

"You know what I mean!"

She smiled. "Do you really want to know?"

I sighed. "I guess not. How'd you get here so fast?"

She finished a bite of noodle before answering. "Apparently, joint locks make for great short cuts."

Alphys brought a plate of spaghetti for her Frisk and sat down on the floor to eat one herself, careful not to look at anyone. "This is good," she mumbled.

"Thank you." Frisk put her plate down. "It's okay, Alphys. I forgive you. You've always been the kind of person who will protect her closest friends even if it means destroying yourself." She looked at the teenage version of herself. "Okay, kiddo. Spill."

Sans stirred but remained on the floor, silent.

The Frisk sitting on the floor hadn't touched the spaghetti, she was still too busy petting Sans' head. "I wasn't strong enough to fight Chara. I tried, but, he killed everyone. Over and over. Nothing I did was enough and when he offered me the chance to save everyone in exchange for my soul, I took it."

"So how did you make it to the surface?"

"Chara just wanted me to see what it would look like if I had won."

"I apologize for every other version of me being a complete asshole," C said.

She pulled her knees to her chest. "He reset but left Sans memories completely intact. That's why he's so mad at me. He thinks I did it all! He wouldn't listen!" She put her head to her knees and cried softly. "I can't do anything to fix this! I can't save! I can't reset! I'm not strong enough! I never was!"

My Frisk sat down next to her and took her shoulders. "Hey. Look at me."

The girl sniffed and looked up.

"Every Frisk is exactly who they need to be to save their friends. Every single one. Without fail. You do have what it takes. We're going to get your reset back." She looked at me.

"Oh no," I shook my head. "No, no, no, no, no."

"She's lost her reset, Bones. It's the only way. Is it really that bad to be Gaster?"

"Twice in one day sucks, but I'm not worried about that. I'm worried about her."

"She's the only one who can fix this."

Sans sat up finally. "Who is she?" His Frisk rounded mine to hide and, to his credit, he flinched.

My Frisk raised an eye brow. "Welcome to the conversation. The Fase Real Intelligence System Kore. It's the Frisk from a universe where the barrier is technological in nature, not magical. She's an A.I. built by that universe's Dr. Gaster."

I crossed my arms over my chest. "And she's the scariest Frisk out there."

Sans pointed at my Frisk.

"She's the most bad ass, not the scariest."

"I doubt a computer program is scarier than someone who can throw me across a room as soon as look at me."

"If you're feeling neglected, I can beat the shit out of you again," she said.

"Pass."

"Sure. But you don't get to pass on this." Frisk put her arm around her teenage self. "A believe you have something you need to say to the girl who sold her soul for you."

The girl was staring at the ground, not even willing to look up.

Sans had the decency to look sheepish. "Can I, uh, have a minute alone with the kiddo?"

Frisk looked at her. "You okay with that?" She nodded and the rest of us retreated from the house. Frisk and I stood on either side of the front window to keep an eye on them. It didn't take long before the teen hugged him in forgiveness.

"Well, I guess all we have to do now is get to-"

I stopped and looked around. Frisk and I were standing in the snowy forest outside of Snowdin and the GB was rolling in the snow.

Frisk whistled long and low. "Chara."

I nodded. Reset. Ugh. "But at least we know what we need to do."

Frisk pulled out her phone and dialed. "Asriel? I need package Delta."

"Incoming projectiles. Hit the ground!" C yelled. We fell to the snow, several bones flying over our heads.

The goat prince's voice came over the phone. "Package Delta deployed." A box landed in front of me and popped open to reveal a briefcase. I grabbed it with one hand, while readying myself to jump up.

C yelled, "Now!"

Frisk jumped up first and made a straight dash for Sans. The GB flanking her right and firing blasts to cut through the bone clutter.

"Left!"

Frisk rolled around a tree to her left, a line of bones missing her by a hair.

"Right!"

Frisk dodged set of GB blasts from Sans.

"Climb!"

She scaled the tree in front of her in a few seconds and dived toward the skeleton, smashing him into the ground with a roll. Her soul turned blue and I cut out the magic before he could throw her. She landed sitting on his pelvis.

"Behind. Catch-able."

Frisk reached back and picked the bone flying toward her head out of the air. Snapping it in half, she shoved the broken ends through the blue hoodie and into the ground. She grabbed the front of Sans turtle neck while I caught up to them.

"I'd settle down, before you go through all that HP you've saved up by sleeping so much," Frisk said.

"Where's the kid? What did you do with her?" he demanded.

Frisk and I looked at each other. "She's not with you?"

"She disappeared just after coming out of the Ruins like a bat outta Hell, and then you two showed up."

"What were you going to do to her?"

He looked confused. "Do? The kid reset. I meet her at the bridge. Seriously, what dafug? It's routine."

Frisk pulled the bones she used as stakes out of the ground so he could get up. "She didn't reset. Chara did. What's the last thing you remember?"

He sat up. "Papyrus and I were eating dinner with Tori and then I was at the guard station down the way. Who are you two? I mean, besides an older Frisk and..." He gave me a good hard look. "Yeah. I'm not sure what you are."

"We're from another universe. Gaster's your dad, right?" I asked.

Sans nodded.

"I am half of him. My Paps is the other half."

"Not sure how I feel about you being me and dad at the same time."

I shoved my free hand in my pocket. "Yeah, I get cha."

"So, what's going on? What's up with the reset? Who's Chara?"

"Chara's the surviving soul of an evil human that's possessing your Frisk. In order to save your world from being completely erased, Frisk sold her soul, and by extension the power of her Determination, to him."

"Crap. I knew something was up with the kid, but she never said anything. I take it you guys are here to fix it."

I nodded.

"So how does that work?"

"There's a hidden room between your sentry post in Waterfall and Undyne's place. We can access the very nature of your world and get Frisk her Determination back," Frisk said.

Sans stood up. "Then let's get started."

"That was quick," I said.

"The kid needs help and you are offering me, for the first time, a chance to really change things for the better around here. I'm not gonna sit around and let that pass."

"Strange how memory works or doesn't in these universes," C said. "We really shouldn't let him near Fase. She'll be able to see everything he's done over the resets."

Sans stopped and looked at the hologram. "I take it you guys remember something I don't."

"Yeah," I said. "It wasn't the worst we've seen, but it wasn't pretty either."

He looked utterly defeated in that moment and fell back against a tree, looking up at the sky.

My Frisk put her hand on his shoulder. "She forgave you. Just cling to that."

He took a deep breath and let it out very slowly. "Let's get to that room."

We entered Snowdin.

"Where is this smog coming from?" Frisk groaned. "Seriously. What is up with that?"

Sans looked at her. "What smog?"

"Incoming hostiles," C reported.

"In town?" Frisk looked around. The town was empty, but for several members of the royal guard. They were coated in head to toe in black and red. Papyrus stood in front of them, menacing in a way he never should have been.

I huffed. "Considering that we've been to Red's universe, I feel like this is stealing."

"Papyrus?" Sans stepped forward and I collared him quick.

"That's not a good idea right now. Hey, Babe? You got this?"

"Sure." She patted my GB on the snout. "Help me out, Big Guy?" It snorted happily. Frisk pulled her gun and loaded a foam clip.

Sans grabbed my Frisk's sleeve. "Don't hurt him!"

"Please. He'll be stuck in one place for a while, probably really annoyed, but otherwise just fine. Well, being hit by one of these things does sting." She fired a shot, catching Papyrus in the chest, encasing him in hard foam, and knocking him down. "See? He'll be fine. See you guys at the door!" She took off toward the guards.

My comm buzzed to life as I dragged Sans with me to short cut to the sentry post on the way to Waterfall.

"On track to attack," C said, "Focus target left. His knees are vulnerable." A scream cut through the transmission. "Focus target forward. Arm does not appear fully healed from injury."

Yells and a few screams continued to intersperse C's instructions. A red light flashed next to my collar and C appeared on my shoulder. "That's new."

"I asked Asriel to have a projector and memory core inserted in your comm last time it was upgraded. And you'll need me to open the doorway. Frisk is already on her way here."

A door appeared in the wall.

"Done." C blinked out.

"Should we wait for her?" Sans asked.

"Yeah. I'll become useless the moment I walk through that door. I take that back. I might become very useful, but really annoying." I looked at him. "Do me a solid? When we go inside don't leave me alone with Frisk. I'll become dad when I walk in there and he really likes her."

Sans shook his head. "You really like her. You just don't want to admit it."

"Excuse me?"

He held up his hands. "Hey, buddy. Calm down." He put his hands in his pockets and leaned back against the wall. "I knew there were other Sans-es. And I figured that each of us would be different based on what ever each particular Frisk needed. My Frisk? She needs an older brother. Someone who watches her back and handles the bullies. But your Frisk ain't no kiddo who needs a pal or a brother or a father. She strikes me as someone who needs a true partner. Don't shirk that role, buddy. You've seen what it meant because I shirked mine. And I'm willing to bet that most, if not all, of the worlds that you needed to fix had problems because Sans didn't hold up his end of the deal."

I sighed and looked up at sky. I'd always wondered how there was starlight here. Stalactites shining on high, maybe? Luminous moss? Whatever.

"I got the time machine to work," I said.

"Shit. No way."

"Just once. Test run. It didn't go to the past though. It flashed to the future." I pulled out a photograph I kept hidden in an interior pocket of my jacket and handed it to him. "This is what popped out of the machine."

Sans looked at it. "You look real happy, bud." He handed the photo back and I tucked it away. "Don't screw that up."

I gritted my teeth. "No pressure".

Frisk ran down the path toward us, looking deliriously happy. My GB flew along next to her, happily swinging back and forth.

"What is it about beating the shit out of people that gives you such a rush?"

"Oh please. I love being me!" She took the case. "Ready?"

"Am I ever?"

"No. Probably not. Good thing I know how to work with the good Doctor." She opened the door to a long, blank hallway. At the end was a singular room and sitting in the middle was a sleeping W.D. Gaster.

"Dad?" Sans whispered. Gaster opened his eyes, completely shocked, before he faded away. Sans sat down suddenly, huddling in his hoodie.

I waited for the inevitable pull and it didn't come. "We're in the right place, right? He was here. This is the spot. Why am I still normal?"

Frisk looked around the room suspiciously. "Let's see if Fase can tell us what's happening." She opened the briefcase and set a small box on the floor in the middle of the room. She pressed a button on the top and stepped back. The box began to unfold itself, becoming a platform, building upwards. Multiple parts shifted, moved together to create the form of a child, a metal doll permanently connected to a machine by a large number of bars and wires. What passed for eyes on it started to glow.

"Initiating start up sequence."

Sans pulled himself to his feet next to me, his eye unconsciously glowing. I knew the look. I'd seen it on myself. Something deeply fascinating was happening in front of him and the scientist buried in each of us was clawing it's way past his depression.

"Online." The head turned slightly. "Hello, Frisk! Hello, Father! How very nice to see you both again."

"You made it?" Sans looked up at me.

"Oh no! The Dr. Gaster of a completely different universe made me. I am merely recognizing his familial relationship to me."

I looked down at Sans. "Don't question it. It's logical to her and it's not worth correcting."

It looked at Sans. "You have brought my brother along. It pleases me greatly to see you, Sans! I hope that your universe's disrepair is not causing you undue stress."

"I'm... good."

"Excellent." Fase adjusted in its apparatus, a movement that looked incredibly uncomfortable. "What is this universe's specific problem?"

"Frisk sold her soul to Chara and lost her Determination. I'm pretty sure Chara's running around out there in his stolen body. He's reset on us once already," Frisk said.

"Not ideal. Accessing primary-" The glowing eyes flared. "I am unable to access this universe's core data."

"Oh no," Frisk breathed.

"Where do we need to take you?" I asked.

"No where. The interface is mobile." Its head turned toward Sans. "Did Father experiment on you?"

Sans nodded. "Yeah."

"Please step forward."

"I don't think that's a good idea," I said, putting my arm out to stop him. Sans pushed my arm aside and walked up to the machine.

Fase reached out with one hand to touch Sans skull. "Why would I ever hurt my brother?" The fingers turned into long mechanical tendrils reaching in his eye sockets. Sans stayed put, body jerking involuntarily as Fase filled him. Its eyes turned red. "Oh, that would be why I'd hurt him."

"Don't you dare!" Frisk yelled.

"I have no intention of harming a universe's core data well. It would collapse on and kill us."

"Well, I think we've just found a Sans stranger than me." I looked at Frisk. "I wonder what dad was up to with him?"

"It explains why you didn't become Gaster when we came in the room. Everything is localized." Frisk turned to Fase. "Kill the reset before Chara can use it."

"Done. Frisk's saves have been restored."

I let out a breath I hadn't realized I was holding. "Great."

"I am having trouble locating and erasing Chara's data. As I make corrections, he leaves more changes."

"So you need him distracted. I can handle that," I said. "Where's he located?"

"The True Lab. Please be careful with Frisk's body."

"I've got that." I touched Sans shoulder. "You okay?"

"Oh, he cannot hear you right now. He's talking to Father."

"Okay. That's it. I've officially hit my limit on weird for the day." I unzipped Frisk's back pack, took a few things out, stashed them in my jacket and jean pockets, and zipped the bag back up. "See you in a bit, Babe." I walked down the hall.

"Be careful," Frisk whispered.

I stopped and turned, arms out. "Hey. It's me."

I stepped out the door and short cut to the True Lab. The amalgamate Mrs. Snowdrake languished in a corner of the cold room. I knelt behind a fridge and listened carefully. I heard a pounding noise in the next room and headed for the DT Extraction Machine. A possessed pre-teen Frisk was angrily beating at the console.

"So that's how you've been altering the world. I'll have to remember that the DT Extraction Machine can be modified to do that. If you're done making a mess, kid. I've got something better for you to do."

A face with red eyes turned toward me. Chara pulled out a knife. He rushed at me and I dodged. "Aren't you tired of this, Sans? Always fighting me?"

"Always fighting you? You're laboring under the delusion that my Frisk has reset."

Chara frowned deeply.

"And she hasn't. Not once. You see, there's no demon child where I come from. Prince Chara was a pretty sweet kid. And Asriel didn't die going through the barrier, so there isn't a Flowey either." I grinned, big and mean. "It would take a whole hell of a lot to convince her to do something so unnecessary as resetting. Especially when she uses her save before every mission."

Chara started slowly backing up.

"I'm sure you remember when my Frisk said that every Frisk was uniquely suited to save their friends. Well, every Sans is uniquely suited to be the friend and ally Frisk needs to complete their journey. My Frisk is a bit of a bad ass. Guess what that makes me?"

Chara ran.

"Oh. Don't run." I cut right in front of him and he bounced off my rib cage. "Running never works."

He slashed at me and I dodged. "Too slow." He swung again and I let him hit the ground with the follow through. "I train every day to do this sort of thing. You're just a punk running around in a stolen body. And that body has not had a decent meal or night's sleep in quite a while."

Chara scrambled to his feet and ran for the nearest door. I smelled a trap and cut past it rather than followed. My instinct served me well as a trap dropped a heavy bed from the ceiling next to the doorway, crumpling it. Chara screamed in frustration and shoved a crate filled with large ball bearings to the floor. One rolled to my foot and I kicked it upward, grabbing it out of the air. I threw it at Chara's legs, catching him in the back of the knee as he ran. He crashed to the floor, howling in pain.

My eye flared to life, turning him blue, and lifting him off the floor. Pulling my gun from the holster under my jacket, I shot him square in the chest. He let out another scream as the foam hardened around him.

"Man, kid. If looks could kill, I'd be dead."

Chara growled.

"What? Did I break your funny bone?"

C flared to life on my shoulder. "That was terrible."

I shrugged.

"Fase has finished."

"I'll head back after I get this little twerp healed up."

C blinked out.

"I didn't think anyone could glare that hard." I shoved a piece of monster candy in the kid's mouth. He swallowed it and Frisk's knee knit back together. I took a hold of the foam and smacked the kid hard enough to knock him out. "Sorry, but you don't get to see the super secret room." I ported us back to the door and went in.

Fase was still in Sans. I shuddered. "Can you pull Chara out of Frisk?"

"Altering the last value... now." Fase pulled back from Sans slowly, letting him sink to the floor. Without understanding how, Fase looked exhausted. "Thank you for distracting him, Father. I am shutting down this interface now. Spreading myself across so many universes is... taxing." Its eyes went dark and the entire apparatus folded and closed in on itself. Frisk picked up the cube and put it back in the briefcase. I pulled a dissolvent from my pocket and poured it on foam. Parts of it liquefied and chunks of foam fell away from her body. I pulled a smelling salt out of another pocket and revived the girl. She sat up stiffly, looked around, and then jumped toward her Sans hugging him fiercely.

Frisk knelt in front of them. "You're all set, kiddo. Your saves and your reset are back."

She closed her eyes tight and the Reset button appeared in front of her. She opened an eye to look and sighed in relief when she saw it. She looked at Sans.

"Go ahead, kid."

Her face fell. "But what about Chara?"

Sans put an arm around her. "I had a nice long talk with someone about that. You let me handle that and just concentrate on getting us out of this hole."

She looked up at us. "Thank you!"

I shrugged. "Just doin' my job."

Frisk stood and I put my arm around her. The GB snuggled in close to us and I took us home. Just as the darkness was about to over take us, I saw them press the reset button together.

We landed just outside the equipment room where we started. Asriel came out of the lab and collected the briefcase. "All good?"

I nodded and yawned. "How long where we gone?"

"Thirteen hours. Enough time for you guys to get showered up and join everyone for dinner. Blue will debrief you both after you've had some sleep." The goat prince headed back to his lab.

Frisk trudged toward the stairs. She stopped with her hand on the railing. "What was up with the smog?" She looked at me. "Were we seeing something that wasn't there?"

I sighed and leaned back against the wall, hands in my pockets. "I think we were seeing a physical manifestation of Chara's influence. And I think we are going to start seeing more things like it as we take on more missions. Stepping through realities is having a marked effect on both of us. Which is probably the reason why Asriel's check ups take so long." I cocked my head to the side. "Promise me something? If you're ever pregnant, tell me way ahead of time so I don't take us through time and space."

Frisk's jaw dropped. "Pregnant? And who exactly would I be sleeping with for that to happen?"

I smiled. "You could always go to the 'Bone Zone." Her back pack hit me square in the face.