Sans x Guardian!Warrior!Reader- My saviour and lover. Well that was a long title. Anyways, this was requested by FlameSama. Hope y'all enjoy! :3
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Your pov

You were a guardian of the monsters. You were also a warrior. You protect every monster from harm. You always loved how they looked and how they are different from each other. You always watch over them and how their life goes on. You have various outfits depending on what your doing.

You protect monsters from harm but you wear your cloak, mask and your black face mask. You weren't supposed to be discovered. Right now, you were watching your TV and saw that rumours about you has spread across the town. They still haven't known you and they named you as 'Mystery Hero'. You giggled. They are really funny when it comes to names. You just sat on your couch, watching TV and occasionally looking through portals to see if any monsters were in trouble.

Sans's pov

"We are back in MTTTV news! Every day, we always see someone in a cloak, saving us monsters. She is a 'Mystery Hero'. Nobody has ever knew anything much about her. In the meantime, we are trying to find out more about this mystery hero. They sound absolutely stunning and strong!" The tin can has said in the TV. I turned the volume low as the can kept on rambling. "Huh. Mystery hero huh? Well, at least something interesting has been happening in here." I saw some pictures of monsters getting saved by a clocked figure. She wears a black face mask, a (f/c) cloak and a mask. "MYSTERY HERO? OH! ACTUALLY, I THINK SHE SAVED ME!" Papyrus said beside me. "Oh really bro?" "YES BROTHER! WHEN A RANDOM HUMAN WAS CHARGING TOWARDS ME WITH A KNIFE, SHE BLOCKED IT AND GRABBED THE HUMAN BY MAGIC AND THE HUMAN DISAPPEARED! THE CLOAKED FIGURE LOOKED AT ME AND RAN AWAY FAST! I COULDN'T CATCH UP TO HER THOUGH BUT IF I EVER SEE HER, I WILL THANK HER FOR SAVING ME!" papyrus said and I flinched slightly at the 'human almost killing my brother' part but I got relieved that the 'mystery Hero' saved him. "That's great bro." Suddenly, we heard explosions outside. We looked out the window and saw an army of humans charging at monsters. Oh no... I think we will have a war again. "Papyrus! C'mon!" I said and went to my room and pulled out a emergency bag from under my bed which has everything that can make a person/monster survive in a month. I pulled papyrus to the secret lab and gave him the bag. "Stay here papyrus. Don't come out until I say so." "B-BUT BROTHER!" "STAY!" papyrus flinched at my tone but nodded. I locked the lab and undyne came running to me. "Sans! Go get papyrus with you and go to a evacuation center! There's a war!" "Nah undyne. I'll pass. Just please guide papyrus to the evacuation center." I unlocked the door and undyne quickly got papyrus and ran to a evacuation center. I sighed and saw a couple of humans charging to me. My eye flowed as I made bones spring it of the ground and stab them. I felt pain on my ribs and my eyesockets widen. I looked behind me and saw a human. He was laughing manically. Black blocked my vision as i collapse. I heard him saying "Monster whore" before I passed out.

Your pov

Your chest ached with pain as you watched the monsters get slaughtered. You put on your armour and put on a mask. You got your flaming sword and fought the humans. You deflected with your sword and had killed a lot of humans already. Your eyes glowed (s/c) (soul color) and all the humans floated
They looked at you and they were scared. You sent them to their town. You saw the monsters shocked. They looked at you and started shaking in fear. You built a force field around you and they couldn't get to you. You felt a stinging pain at your chest and you saw a skeleton was laying on the ground, unconscious and is between life and death. You walked to him and the other monsters stopped. You picked him up and saw that he has a knife stuck to his ribs. You sighed worriedly. "LEAVE MY BROTHER ALONE!" you looked beside you and saw a tall skeleton. He has tears coming out of his eyes and he was running to you. You looked at the limp skeleton on your arms and healed him. The knife was pulled out and his stab wound is healed. Monsters looked at you in awe. You opened a portal and stepped inside it. "NO!!! PLEASE TAKE ME INSTEAD! DONT HURT HIM!!!" the other skeleton said and you just smiled at him. You went through the portal and you heard the skeleton shouting, desperately trying to get the short skeleton with him but you already closed the portal. You laid him down on the couch and got his soul out. You saw that it is only a fraction left and you stopped it from turning to dust completely. You got some dust from your small pouch and sprinkled it on his soul. It started to form until it was completely whole again. You carried him and opened a portal to his house. You laid him down on the couch and you saw the tall skeleton and a fish lady. They saw you and ran to you furiously. They stood in front of you and they saw the small Skeleton and they looked at you, more furious than ever. "WHAT DID YOU DO TO HIM?!?!?!?!?" they shouted at the same time and you got out your device that has all the monster's informations.. You saw that their names are papyrus and undyne while the unconscious one is sans. "Do not fret dear monsters. I shall not harm-" "NOT HARM?!?!? HARM MY BUTT!!! WHAT DID YOU DO TO HIM?!?!?" undyne said. "If you could just please let me-" "WHAT DID YOU DO TO MY BROTHER?!?" you sighed. "Just please. Let me finish." They stayed quiet but they were still angry. "Alright. I do not intend to harm you all. I just took him-" you pointed to sans "to my humble home and gave him something. It shall help heal him. So please, if you have enough patience, he will heal completely." They looked at you and you can feel that they don't believe you. Just then, you heard groaning. You looked and saw that sans has woken up. "well then, i shall let you all be. I have to go. Farewell." You opened a portal to your house and went in it. Just before you can though, blue magic held you in place. "What are you doing here?" You turned around and saw that sans is angry at you.  "Oh. I had just put you here and if you could please excuse me, I shall attend to my business." You broke the blue magic and went in the portal. It... Disappeared? You looked at the where the portal once was and that place has a pile of bones, Spears and more bones. It had happened so fast that you didn't saw what happened. You looked at the three and they were really furious. You felt stinging pain in your chest. Another monster was dying. You quickly opened another portal and went in there and closed it. You made yourself invisible and saw that a monster was on a hospital bed. They died. The others were crying. You took out the dying monster's soul and made a bubble to protect it. The others cried as you opened a portal (that they can't see) and went through. It was the room for when monsters due, they go here when it is their time. The only reason why you healed sans because it still wasn't his time. You made the bubble float along with the others. It was beautiful. The room was in waterfalls but it was in a super secret area. Only you know about it. The bubble that has souls in it was floating freely. You opened the portal back to your house. You went In and plopped down the couch. You turned on the TV. " A random human girl has been seen in the war helping monsters! The humans were confused to see that they were back to their town. They are now going back to the monster town to continue the war." You sighed. These human really are determined to defeat these poor monsters. You put on your armor an got your sword. You opened a portal and it was surprisingly in the skeleton's house. You went in and you saw the sans watching TV and you heard something cooking in the kitchen. Must've been papyrus. You closed the portal and sans noticed you. He pinned you to a wall using blue bones. "What do you want?" "I deeply apologize but I have to go outside. Another war is coming this way and I must protect all of you." "I don't believe you." You sighed and with the last of your magic, you broke the bones and went out of the door to see human armies charging. Humans charged at you and you blocked their attacks with your sword. You don't have any magic left so you have to do this. You deflected bullets, bombs, daggers and swords and swung at them. Monsters still haven't known about the war because the news is only in the human town. You deflected and swung. You got some scratches here and there but that doesn't matter. You charged at the humans with all your might and some got blown away by your shot. You were getting tired but you were not giving up easily. Others had died but you still kept going. This was getting hard but next thing you know, you saw some monster attacks coming towards the humans. So the monsters already found out? You swung your sword and it blew away a lot of humans. There are into a few left but they were really determined. You swung and deflected. Swing! Swing! Swi- you felt pain on your chest. You looked down and saw that a sword was stuck to your torso. You sliced the human who did that. You swung with all of your energy and it blew away the rest of the humans. They stood up and ran. You were now on your knees, clutching your chest. You don't have enough magic to form a portal. You collapsed to the ground and your vision went blurry and you heard footsteps coming towards you. You blacked out...

You soon woke up. We're you dead? You looked around you and you were in a hospital. Your soul was pulled out and you looked in front of you and saw a lizard lady. She looked at you and smiled. Your soul was (f/c) and it was half monster soul, half human soul. It has small, white swirls and a golden aura. You stared at it as the lizard stared at it in awe. You looked down and realized that your chest was bandaged. "W-why is y-your soul l-like t-that?" You shrugged. You don't really want anyone to know that you are a guardian. You heard a faint beep. It means that a monster was getting born and you have to create it's looks. The bandage on your chest melted and there are no stab marks there. You took up and alphys stopped you. "P-please just r-rest!" "No. I need to do something quick." You ran to the bathroom and locked it. You opened a portal to the 'Creating room' as you call it. That's where you create the looks and personality of the baby. You went in and quickly closed the portal. You saw that the parents were a butterfly monster and a mouse monster. You pulled out a pencil and Drew the outlines of the monster. Then, you colored it. You put his soul color and personality. He's a boy. You put it in a machine and the baby will be made and will get born. You smiled. You opened a portal and you were in the bathroom again. Next thing you know, the door was blasted to pieces. Sans,undyne,papyrus and the lizard lady went in. You looked at your device and saw that the lizard lady was alphys. Alphys sighed in relief. "P-please don't do that again. W-we were so w-worried!" She looked at your device. "S-so your name is (y/n), c-correct?" You smiled and nodded. Your name was at the back of the device anyways. "I-im alphys. O-Over there is U-undyne, papyrus and sans." Alphys said as she pointed to them. I already knew their name but I played with it. I smiled. I put my device back to my pocket. "Well... Umm... I can go now right?" "W-wait... y-your not supposed to go." "Sorry alphys but I gotta go. Got some business to take care of." I said and turned invisible. They didn't see me. "Where did SHE-" sans asked and looked around. I snuck behind them and sneakily opened a portal and jumped in. I closed it and turned myself visible. "Phew! What a exhausting day." I said and plopped down the couch and fell asleep.

I woke up again and the TV turned on. I watched the news. Nothing interesting. I checked every single monsters. No one's in danger. I sighed and plopped down on the couch again. What am I gonna do now? I opened a portal to the skelebro's house and plopped down their couch. They still haven't saw me and I closed the portal. Sans went in and saw me. "How did you get in here?" "I went here earlier." You lied but he bought it. "Well okay. What are you doing here actually? And where did you go yesterday?" "1. I have nothing to do 2. Not to be rude but it ain't your business." "Wow. The last days you talk so formally and now you talk like a normal person. Huh." He sat down the couch with you. You guys talked about yourselves. You talked to him but you didn't say that you were the monster's guardian. You just made up a life like, you living in a wood house, having a brother/sister, school and stuff. All of that stuff is fake but you need to not get identified. He bought it though. You learned that he loves puns, his brother and he doesn't really take the resets happily. You knew that resets we're a thing. You also lived through it all but now it's finally over. You and sans talked and he had asked a question you don't really want to answer. "Actually, when we first met, how did you make portals?" You held in a gulp. "W-well, one of my parents have a power like that and you know, being their child means that I have their power. Ehehe..." You scratched the back of your head but he bought it. "Cool." You two sat there in silence until you felt a stinging pain in your soul. "Sans, hold on, I have to go to the bathroom for a bit!" You said and ran there. You locked the door and opened a portal. You saw a monster dying. You turned invisible and jumped in, closing the portal after. She was below a tree. She was crying but yet, she still smiled. You looked at your device and saw that they have a case of cancer. They were going to die a few more minutes later. You looked at her and she was a cat monster. She has ginger fur with three white stripes each at her cheeks. You smiled as they closed their eyes and entered a never ending slumber. Their body was slowly turning to dust. You grabbed their soul and put a bubble. You went to the waterfall room and set the soul free. It started floating freely with the others. You smiled and sat down, watching the souls floated by. They were so beautiful. It was so peaceful. You sighed and opened a portal to the bathroom. You went in and closed the portal. You heard knocking. "(Y/n)? Are you okay? You have been there for half an hour." "I'm fine sans. I'm fine." You opened the door and saw sans. "Did ya fell asleep on the toilet or something?" You giggled. "No I didn't." You two walked down the stairs. You heard a gun shot and a scream. Your chest ached again. But that scream was no ordinary scream. It was Papyrus's scream. You and sans gasped​ and ran out of the door to see papyrus slowly turning to dust and you saw a human with a gun. You were mad and charged at him. You sliced him and he was dead. You got rid of the corpse easily and you saw sans crying, holding Papyrus's scarf. You saw Papyrus's soul floating. You walked to it and put it in a bubble. "W-what are you doing *sniff* (y/n)?" You looked at him sadly and opened a portal. He put the scarf in his pocket and looked at the portal. You went tin with Papyrus's soul and sans quickly followed. You closed the portal and you were in the room again. Sans looked at all the souls. You went to a special room in the soul room. That's where you out some special souls. There was only one other soul in here. That was a soul of your monster friend.
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W.D gaster. You are friends in the underground. He's the only one who knows that you were a guardian. One day, he fell into one of his creations. You knew sans and papyrus were there to see it. Sans thought gaster was still alive, he was just stuck in space and time but no. He was really dead. You saw his soul in the lab where he died after sans and papyrus left and got it. The one that they see in the shadows is just an illusion. He want really real. The real one is here, dead. You set Papyrus's soul free. It floated with gaster's. "Who's soul is that?" "That is gaster's soul" you looked at sans and he had a look of disbelief. "He died sans. If you see him in the shadows or even see him at all, he's just an illusion. Nothing more than that." Tears was on his eyesockets. It flowed down to his cheeks and to the ground. He felt alone and hopeless. He knew that frisk can't reset anymore. He held his face in his hands and cried softly. You softly embraced him as he cried and trembled softly on your shoulder. You shushed him. "Sans, it's gonna be okay..." You rubbed his back. After what seems like hours of him crying and you shushing him, his trembling slowed down as he tried to catch his breath. His breathing was stable and soon enough, he fell asleep on your shoulder, emotionally drained. You carried him and opened a portal and went upstairs to his room. You tucked him in bed and gently Pat his skull. He had been through so much right now. You got a chair with telekinesis and put it at the side of the bed. You sat down and put your elbow on the bed and your hand on your cheek. You softly caressed sans and you soon fell asleep.

You woke up and sans was still asleep. You looked at her clock. 6:00. You got up and went downstairs. You opened the fridge and mad breakfast. You ate some quickly and grabbed a plate of breakfast. You out it on the chair you sat on at the side of sans's bed. You left a note saying that you have some business to do and opened a portal to go to your room. You went in and closed the portal. You took a bath and changed into another one of your 'guardian dresses' and opened some portals. The monsters were fine. You opened the TV. You watched the news. Nothing... You sat on the couch and watched TV. As you were slowly falling to sleep's grasp, "BREAKING NEWS! Humans are sending a nuke bomb to the town of monsters to get rid of them once and for all." You shot up and opened portals. You made the news program go in their tv so that they knew what is happening and they quickly got ready. You went to sans's house and he was on his bed, staring emotionlessly on the ground. He ate his breakfast though which is good. "Sans! We have to go! A nuke bomb is on their way here!" "What's the point? I have nobody to live for. I did have some but they are DEAD. Might as well join them." "Sans! This is no time for that! Come on!" You said and grabbed him with telekinesis and grabbed two bags full if supplies to survive for 2 months and went to the middle of town. You set sans down and summoned a megaphone. "EVERY MONSTER IN THIS TOWN! WE HAVE RO EVACUATE TO MT. EBBOT TO GET AWAY FROM THE MISSILE! GO TO THE BARRIER NOW!" they all ran to the mountain and you made sure nobody was left behind. Their town was far from MT. Ebbot so it's safe. You grabbed sans and teleported to the mountain. Everybody was already there. "ALRIGHT EVERYONE! GO INSIDE THE MOUNTAIN AND GO BACK TO YOUR OLD HOUSES! I WILL BUILD A FORCE FIELD TO PROTECT US FROM ANYTHING THAT THE HUMANS THROW US!" they ran inside and you made a force field. You carried sans and went in the mountain and every monster in there was heading to their old houses. You headed to snowdin and ran to sans and Papyrus's old house. Before you can go in though, sans slipped out of your grasp. You looked at him. "Sans? Come on. Let's go inside." He didn't say anything. You looked at his now lifeless eyes. It sent a shiver down your spine. Sans teleported. You looked to the portals and he was back in the town. You saw the meteor coming. You teleported there and grabbed him and teleported back to snowdin. You prevented him from teleporting. "Sans! Please! Don't do that!" "What's the point? There's no point in living now." "Sans please! Live for everyone! Live for me... We need you here... Please don't go... Your important to us... To me... To everybody...." You hugged him and sobbed. You quickly wiped your tears and let go of the hug. "Don't lose hope." You went in the house. You sat on the couch and sighed. Protecting monsters really is hard. Harder than you thought. Especially interested his situation. You checked the monsters and they were fine. You sighed sadly. You just wished that sans can cheer you up with his puns and papyrus can also make you smile with His childish antics. Too bad that it ain't happening. The door opened but you didn't really noticed. You summoned Papyrus's soul. It was still glowing a bright orange. You smiled and put it back to the special room. You felt someone hug you from the side. You looked and saw sans. He was smiling and his eyes held life again. He let go. "Your right (y/n). I shouldn't lose hope. I need to live for everybody. Thanks for the advice." You smiled at him. "Glad your back to your normal self sans." "Of course! 'sides, I have to tell you some rib tickling jokes that can tickle your funny bone." You giggled. You just imagined papyrus yelling at sans because of his puns and it made you giggled more. "Gee. Was I really that punny? I really did put more backbone to my jokes!" You both laughed. You really loved this side of him. He was so cheery. It was like you just wanted to see this side of him forever. You both stopped laughing. "Want to visit undyne and alphys?" "Sure." You opened a portal and went in. You and sans was in the lab. Both alphys and undyne was in there. Sans has and arm on your shoulder. "Hey alphys! Hey undyne!" They looked at you and sans. Undyne looked sympathetically at sans. "Sans. I'm sorry for papyrus. He must've meant a lot to you." "It's okay undyne. (Y/n) here had kept my hopes up. Without her i would've died by the missile." "Oh shush you! I didn't do much!" "Yeah sure. Anyways, how's things going?" "H-HUMAN are still a-after us and g-good thing that they t-thought that w-we were dead. T-they wouldn't go a-after us if we s-stay here." "Yeah! So we can just stay here!" "B-but how can we g-get more supplies if we r-run out?" "Then I will just go and buy some!" "Great thinking kid" you all agreed to the plan and you all stayed in the underground.

A year later...

UT has been a few months since you all stayed here. You lived with sans and you actually enjoyed it. You and sans had became inseparable and you even gained a crush on him. It ended up to both of you confessing at the same time. You two laughed and you became bf and gf now. You were really happy. You had soon revealed that you were a guardian and sans was shocked and happy. You soon revealed that to all the monsters and they treated you with respect. You were finally happy. Sometimes, you and sans saw ghost versions of papyrus and gaster and both of you smile at them and they smile back and disappear. A few months later, sans proposed to you and you happily agreed. You were soon married and had two children. One is a boy and one is a girl. The boy is older. His name is (s/n) while the girl's name is (d/n). You four lived happily in the underground, spending happy times together.

The end