Random Smut & Lemons | Oneshots

✨ Smut ✨

Fandom: Undertale/Deltarune
Ship: Sans x Fem!Reader
Theme: Valentine's Day | Adult AU
Requested by: 12ashlea

(It's Valentine's Day, and Y/N goes into heat— Sans is giving everyone valentines cards— Sans is top...somehow.)

Additional Info:
[ Y/N ] = Your Name

Warning: Sadomasochist things, have fun.

San's POV

It's Valentine's Day, the day of love and happiness..and whatnot. My brother gave me the important task of sending love letters to every single person in the Underground. So, here I am, slowly walking through town, hot dog in one hand, and a gigantic bag behind me in the other. I ate my hot dog as I slipped Valentine notes into everyone's pocket...or just hide it somewhere. Anywhere. Once I had finished my hot dog, I tossed the trash away and bought a nice cream, then continued on my journey through sending letters to everyone in the underground.

Soon there was only one letter left; for Y/N. I went to Grillby's, nothing. I went to the ruins, nothing. Went to the castle, nothing. I went to Napstablooks, nothing. I sighed and gave up, so I went back home, only to run into Papyrus. He smiled and waved at me, then we started conversing. "Hello there brother! Did you finish mailing those letters for me?", Papyrus asked. I shrugged, "Nah, have one left." He cocked his head to the side and placed his hand onto his chin, "Oh? Who did you miss?" I shrugged once again, "Y/N. Do you know where she is?"

Papyrus laughed, "Yeah! She's inside your room. Anyways, Alphys and Undyne want to play this game called..D&D..so I'm gonna go! Bye brother of mine!" Papyrus walked away, proud as he whistled out into the distance. I shook my head and sighed as I opened the door to my home, plopping the now empty bag into the side of the stairs. I walked up to my room only to find Y/N nowhere in sight. Confused, I scope out the whole room but to no avail, so I shrugged and closed the door behind me. I yawned as I plopped myself onto the bed and closed my eyes for a split second.

The moment I opened them again, Y/N was there. "Gah!", I said startled, pushing you off and crawling up to the side of my bed. You laugh and then sigh. "Sorry, I-I didn't mean to scare you.", you said as you fixed your hair. I shrugged and yawned, "don't worry about it. But uh, what are you doing in my room?" You shyly looked around the room and then looked directly at the floor as you finally spoke, "I'm kinda..hoping you would help me on something?" If I had eyebrows, they would've been raised, but since I don't I just asked, "ok, help with what exactly?"

You fiddled with your fingers, your face turning a bright red as you began to softly answer my question. I leaned closer, "huh? Sorry I couldn't quite get that." You said it again but I still couldn't figure out what you were saying, so I asked once more and you then shouted, "IM IN HEAT!" There was a long silence before I responded, "you mean that thing animals do when they hor-" you muffled my mouth with your hands, your face flushed with embarrassment. I chuckled as I pulled your hands away from me. "So what did you want me to do. Hm?", I asked with a suave voice.

You looked at the bed, fiddling with your fingers again in nervousness. I hummed as I looked around the room, then got out of my bed. You looked at me, watching as I close the blinds and lock my bedroom door. I then sat back down onto the bed next to you, and smiled. I patiently waited until you were finally ready to explain what you'd like me to do. You took a deep breath and finally spoke, "Okay..do you have uhm..a.." I shook my head and sighed, "I'm a skeleton." You sighed, "Okay, do you have any experience with doing any stuff like this?" I nodded my head and smiled, "Yeah, I have some experience. Would you like me to lead this instead?"

You nodded your head and smiled, blushing as I helped you lie down onto my bed. I scooted my way to my bed's drawer and pulled out some bondage ropes. I slowly took off your clothes one by one, starting with your socks, then your jacket, your pants, then shirt. I also took off any and all of your jewelry. I then picked up the rope and tied your hands to the bed, tightening them enough to keep you there but not tight enough for you to loose blood circulation. You look up at me in anticipation, biting your lip and moving your hips side to side, rubbing your legs together. I pulled out some lube from my drawer just in case. "I promise I will go easy on you.."

You nodded your head as best as you can as I slowly slipped your panties off, and then unclipping your bra. I licked my..oh wait, I don't have lips. I shook my head and wiped some lube onto my fingers, then slowly inserted one finger into you. You gasped as I went deeper, and you rubbed your legs together. I groaned and then pulled out another set of ropes, spread your legs, and then tied your legs. "Stop wiggling, and I'll go harder..okay?", I said politely. You nodded your head, softly biting your lips. I sighed as I inserted two fingers, then three, then four. Your whimpering, your moans, they filled the room.

A slight blush ran across my face and I pulled my fingers out of you, then cleaned up my hands with a tissue. I leaned my body closer to your ears and smirked, "I'm not done yet, I got a toy I'd like to use." I walked to my closet and grabbed something I never thought I'd ever use in my life. I turned my head to look at you, and I wrapped the strap onto me. I slowly crept up to you and slipped it into you. You moaned loudly from this new sensation, and I continued to thrust into you. Your bodily fluids slipped out of you with each thrust, ruining my poor clean sheets. I then place my hands onto your breasts, slowly rubbing them as I continued to thrust in you.

After a few minutes of this, I grew tired physically, so I slowly pulled out of you and groaned loudly. You looked up at me and sighed, "Can we go a little longer?" I shrugged my shoulders, "I'm tired, but I can go again in a couple minutes if you'd like." You nodded your head and smiled. A lightbulb went out and I snapped my fingers, "actually, I have an idea." You raised an eyebrow and I walked back up to my closet, pulling out a paddle and whip. I turned my attention back to you, holding them both in hands, and smiled."So uh..Do you like pain?", I asked. You but your lip and nodded your head violently.

I smirked and helped lay you on your backside, tying you up once again and then sighing. I grabbed the paddle and whip and turned my attention to you, "do you want me to whip you or smack you first?" You hummed for a few seconds, thinking about it and then finally made a decision, "I think whip would be nice right about now." I shrugged and put the paddle away, then started to whip you, starting from your legs, your ass, and then your back. You had red marks everywhere, shrieks escaping your lips every time I strike. Once you got tired, I put the toys away and untied you. I then put your undergarments back on, then cuddled beside you, drifting off to sleep.

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Alright y'all I'm done with this fanfic, have a good Valentine's Day.

Love y'all.

Also yes I'm still trying to finish the rest of the fanfics, give me some time.
~✨💙