~ Sans's POV ~
When I was fighting y/n, I flung her to the ground, the tracks covered in her blood.
serves you right, you dirty brother killer, I thought.
I was standing over her, looking down at her body that was in horrible condition.
"your way weaker than the others, since i can tell your DETERMINATION is unstable. which makes it easier for me to do this." I said to her.
We both heard footsteps, quick and heavy, like they were on the run from something. I didn't need a monster to think I was the killer here, so I snapped my fingers and both my Gaster Blasters disappeared. I looked to see who was coming, and y/n got up and ran towards the Waterfall entrance.
"get back here!" I yelled, but she kept running. I sighed and saw Toriel coming towards me. She was out of breath.
"Sorry...I'm late...Sans..." She stood up straight and looked around after catching her breath. "Is y/n here yet? I can't wait to see my child!" She sounded so excited.
"no," I then said, feeling horrible for the things I did to her, but not super horrible. I was still super angry at her. "she may still be out with pap." It pained me to say Paps name, but I got through it.
"Alright. I'll be inside if you need me." Toriel then gained a happy look on her face. "Oo~! I can't wait to see y/n again! It's been weeks since I last saw her! I hope she gets really surprised!" She then leaned down to my hight. "This is a grand idea Sans, and I bet she'll love it." Toriel gave me a hug then went to the house.
My laziness kicked in, so I was going to teleported to where y/n was. I'd love to finish her off when I find her, but it'll destroy Toriel, and I don't want anyone else in pain.
I arrived at the Waterfall entrance and started looking for y/n. Then I heard singing.
"Go ahead and just hit me since your able,
"We both know my DETERMINATION is unstable,
"I'm not even mad because I keep on dieing,
"But I don't even know why I'm trying.
"I'm made o-o-of, lo-o-o-o-ove,
"lo-o-o-o-ove.
"And I'm not stronger than you..."
She then went and lied on the ground. I just watched her. Y/n wasn't going to change my mind about her killing my brother over a song.
I left her there and started heading back home. Maybe I could convince Toriel that something happened to y/n and that she'd never come back. I'll think about it later.
Then, I heard an all to familiar voice.
"Y/N! HUMAN! DID YOU MAKE IT BACK HOME, OR ARE YOU LOST, BECAUSE THE GREAT PAPYRUS CAN HELP YOU!"
"p-pap." I stuttered at a loss for words.
I ran out of the Waterfall entrance to see Papyrus looking around for something...or more like someone.
"papyrus!" I yelled as I ran to him with tears in my eyes and probably looking dumb. Papyrus keeled down to my height and accepted the hug that I gave him when I reached him.
"WHAT'S WRONG SANS?" He asked, pulling away. "AND HAVE YOU SEEN THE HUMAN?"
"no, i thought you both were still at undyne's. tibia homest, i thought you were dead, since you never called or texted me."
"FIRST OFF, URG SANS! YOU'VE DONE ANOTHER HORRIBLE PUN! SECOND, I HAD TO RUN BACK TO UNDYNE'S EARLIER, SINCE I LEFT SOMETHING THERE. Y/N, UNDYNE AND I ALL MADE SOME SPAGHETTI, AND Y/N GOT VERY MESSY DUE TO UNDYNE'S CARELESSNESS. HER SHIRT WAS COVERED IN TOMATO SAUCE AND I FORGOT TO TAKE THE KNIFE SHE HAD BACK TO UNDYNE AS WELL, SINCE THAT WAS HER'S. THE KNIFE WAS STILL DIRTY WITH TOMATO SAUCE, SO I HOPE SHE DIDN'T LOOK SUSPICIOUS."
y/n...I thought. she...wasn't lying about payrus....
I then felt tears of guilt, but I quickly made them disappear for Pap. I turned and ran back to the Waterfall, but Papyrus yelled again.
"SANS! WHERE ARE YOU GOING?!"
I turned to him. "i forgot something at my station! go back home, and we'll surprise y/n when i get back!"
"ALRIGHT! I CAN'T WAIT!"
Papyrus then started to head back home with a super happy grin plastered on his face. I, once again, turned and ran for the Waterfall, letting my tears of guilt fall where they may.
I arrived back to y/n's body, it lying still on the ground. I got on my knees and cried even more.
"please," I pleaded to her, "please don't be dead! please!" I lifted her body and placed her head in the nape of my neck and I cried into her shoulder.
"i'm sorry! i only did that cause i thought pap was dead! i've seen it one to many times before, and thinking that you did it another time broke my heart! just please give me a sign that your not dead! please!" my voice was about to go, since I was yelling so much. Then I heard it.
Breathing. Soft and hoarse, but breathing.
I smiled, knowing she was still alive. I picked y/n up bridle style and teleported back to the house and burst open the door. Toriel was on the couch and Papyrus was in the kitchen. They both looked at me.
"SANS," Pap cried, "YOU'VE RETURNED! WHERE DID YOU FIND THE HUMAN?" He asked, now looking at y/n. I started crying once again.
"at the waterfall." I looked at Toriel. "tori, call alphys and tell her it's an emergency! y/n is seriously hurt and needs help now!" Toriel nodded and got on her cell phone.
Papyrus helped me carry y/n to my room and we placed her on my bed. Her bleeding from earlier had just about stopped entirely, so I had Pap go to the bathroom and get our first aid kit. I cleaned her wounds the best I could, and I did a pretty good job, but now I could see all her wounds caused by me.
Bruises everywhere big and small, cuts up her torn pants and down her arms, a few scratches on her head and tear streaks down her cheeks.
Pap looked at me starring at y/n. He spoke, but it was a lot quieter than normal.
"I'll leave you and y/n alone for a while. I check on Toriel and see how we are with getting Alphys here."
I smiled at him. "thanks pap."
He came over and hugged me, "Your welcome brother."
We then heard laughing. Soft, like it was seriously forced. We looked and saw y/n's e/c eyes open and she looked at us.
"I...didn't know you could speak so softly...Pap..."
"y/n!"
"HUMAN!"
She laughed again, but this time it was a little louder. "Now that's the Papyrus I know." She smiled.
"i'm so sorry y/n!" I cried, "i didn't mean for this to happen-" she put a finger to my mouth and shushed me.
"Sans, I heard everything you said at the Waterfall. I know how it feels, to loose someone you truly love." She looked me straight in the eyes. "I forgive you Sans."
I smiled and got teary again. I was just so happy y/n was alive. She placed a hand on my cheek and wiped an oncoming tear and laughed.
"i'm happy you forgive me."
"How could I not? You were the first-well, second-monster to actually save me from death. I'm glad you helped me Sans." She started to sit up.
"no no no. you need rest."
"And you need a hug." I gladly accepted the hug she said I needed. We both heard the door open behind us (honestly, in the game, I haven't been in Sans's room yet, so if you know what it looks like, the imagine it the right way and don't listen to my dumb mouth.) and looked to see Toriel walking in and she shut the door behind her.
"Sans, Alphys will be here in a little so I just came to..." She trailed off when she saw y/n. Y/n saw Toriel at the same time as well.
"My child..."
"Toriel!"
I moved out of the way and thank goodness I did, or I would've been squished. Toriel ran towards y/n and embraced her, both of them crying tears of joy.
"You came back!" y/n said in tears.
"I told you I would." Toriel replied.
"look, i'm glad you two are happy, but next time you try to crush each other in a hug let me know. i was about to become a sanswich."
"Oh my gosh Sans," y/n said after Toriel and her released from their hug. "That was just terrible."
I shrugged. "it's my thing."
We all laughed and then Toriel and I left to give y/n some rest. I went and sat on the couch and fell asleep.
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Sorry if this was filled with feels, and if it's to long, I'm trying, ok? Thanks.
-MysteriousKyrgy