So here it is… My first attempt at a NSFW Chapter. Ever. So, uh, yeah. I wrote it like a normal chapter before I remembered it was supposed to be NSFW. Enjoy you sinners.

PLEASE DO NOT READ IF YOU ARE UNDER 18 YEARS OLD

Chapter build: Reader is at least 18 years old. No genitals specified.


"So. You were holding out on me." Sans' voice woke you up from yet another strange dream you were having, confusing you for a moment before you realized you were in your own room. You looked up from your pillow, seeing him standing beside the bed and leaning against the wall with his shoulder, other hand behind his back.

"Wha-?" you ask, question cut off by a yawn and stretch.

"You never explained to me what the deal was with all the Souls that were decorated throughout the stores." He clarified.

"The hearts?" You asked, vaguely remembering the last time you walked through downtown with the short skeleton, and the conversation that started. You had told him it was just some holiday that you didn't care much for, saying that you'd explain later. That was three days ago, and you realized that you left Sans without answers the entire time. So that means…

"It's Valentine's Day. I had to learn about it from Alphys." Sans continued, pulling out a blue rose from behind his back. He smiled sheepishly, his cheeks starting to match the rose. "Happy Valentine's, Vertebae."

"Oh noooo." You half groan and bring your hands to your face, rubbing the sleep out of your eyes. "Now I remember why I didn't explain it to you." You brought your hands down and turned to Sans, and immediately noticed the pale nervousness on his face. "No no, you're fine." You quickly sat up and faced him. "No, better than fine, this is adorable and all, but that's why. I don't like dedicating a special day to do sweet things for your significant other, especially since there is such a pressure to do so today. If I want a special day for someone, I want it to be because I wanted to, and my choice of day." You quickly explained.

"Oh, I'm sorry then." Sans said, lowering the flower. You reached out and wrapped your hands around his, keeping the rose high.

"Don't be. I'm one of the few humans out there that don't enjoy this human holiday." You laughed lightly, feeling bad for shutting down his Valentine. You just didn't want him to feel pressured into this silly celebration.

"Bad experience?" He asked, not looking quite as dejected when he raised an eyebrow.

"No, well… Rather lack there of, but…" You drifted off, trying to think back to your previous Valentine's Days.

"You haven't had a partner for previous Valentines?" He asked, looking shocked. His eyes drifted down your body for a second, just slow enough for you to catch it.

"Oh no! I had partners around this time. Its just that we never did anything special, or if we did, it was just disappointing because of all the expectations." You glaze over the details, not really wanting to talk about previous relationships with him right now.

"Oh, well... I was gonna say 'good' but I suppose that's not very good?" Sans laughed a little, scratching the back of his head. "How 'bout this then? We do a not-so-human holiday?" He asked, drawing more of your attention.

"Hmm?" You were admittedly curious as to what he had in mind.

"Well, the underground had a holiday sorta like this, but a bit different. When others were in a relationship, they'd get a day to treat their significant other to anything they wanted. The day was chosen by random unless they had bigger plans, so the pair usually could sneak it in without choosing the same day for each other, though it is funny when that happens." He continued, coughing a little and getting back on track. "We call it Other's Day. Interested?"

That did sound a lot better than the human version. "What does it consist of?"

"Oh, not much. Some good food, some bad laughs, some nice massages?" Now he's talking.

"So let me get this straight, Other's Day is a day where you treat me, and I…?"

"Be as selfish as you can. Today is about you, not me. I'm going to try my best to make you as happy as possible, but if you have better ideas just let me know and we'll do them. I'll do whatever you want." He smiled, seeming excited.

"Well… Sure, I guess. That means I can give an Other's Day to you any day right?" You asked, just to make sure. If that's how this worked, you could really get used to living the monster life.

"Absolutely. Now get out of bed, and get your most comfy pajamas on." He ordered lightheartedly, quickly walking out of the room and leaving you with the blue rose in your hands. You bit your lip and smiled a little, doing as instructed. You put on incredibly fluffy pajama pants and a red tank top with the words "I make this shirt look good" on, already feeling more comfortable about today.

You walked down the hall and passed the kitchen, smelling something absolutely wonderful being cooked, and your stomach growled audibly. Sans laughed from the kitchen, apparently hearing it.

"Sit down in the living room, I got you covered." His voice said, and you made your way to the couch. As soon as you sat down, a massive blanket appeared around you, already warm from the dryer. You couldn't help but to hum happily as you grabbed the corners closer to yourself.

"Here we go." Sans walked up to you with a small plate with what looked to be an egg sandwich on it. You smiled, surprised that he cooked breakfast for you, and grabbed the plate. It looked different from any egg sandwich you had at fast food, but you figured that was a good thing and bit into it.

"Oh my god." You mumbled, mouth full of the food. You barely chewed before swallowing. "This is wonderful," you tried to say, muffled around another bite, but you were sure Sans understood anyway. He brought over a wine glass of something red and bubbling, and you took a sip. You raised an eyebrow at him. It may have looked like wine, but it tasted way too sweet and fruity to be.

"Sparkling champagne." He answered your wordless question. You laughed and continued eating.

After a few more bites, the wonderful sandwich was sadly gone. But damn did it taste good. "I thought you couldn't cook?" You asked Sans, remembering how Papyrus always complained about being the only one to ever cook, and how he never offered since he has been here.

"I never said I couldn't, I can make a mean quiche. I just prefer not to." He smiled, taking your plate and dropping it off in the kitchen. You laughed, and looked around.

"Where's Papyrus?"

"He's on a double date with Mettaton and the girls. They decided to give the whole Valentine's thing a go." He put a small dish onto the counter, along with a stick of incense, and lit the end of it with the lighter you left on the counter. "So they'll be out all day, and we have the apartment to ourselves." He smiled and walked over, sitting on the couch beside you.

"I have something cooking in the oven right now, but they have a while yet." He paused. "I'll be honest with you, I don't have anything actually planned today…" He smiled, giving a slight laugh. "What do you want to do?"

"Lets see… to be honest, I mostly just want to chill. Like we did for our shitty movie day." You said, and Sans immediately got up to grab the remote.

"Sounds great." He turned on the TV and the two of you got situated.

.

You cuddled under the warm blanket for a long while and watched a movie about bees suing humans for honey (the entire movie seemed like a giant joke so far, to be honest). After a little while Sans's phone went off, and he quickly went to the oven. You tried to get up and follow him, but he "Ah ah ah"-ed you and you sat back down, curiosity at what he was cooking eating at you.

He pulled… something out of the oven, you couldn't see it, but oh man you could smell it. Something sweet, but not cake or pie… He sat back down next to you, and you kindly flopped against him. He laughed, saying it needed a while to cool, and continued the movie.

A few minutes later (and a few laughs as well) your stomach growled from the smell of whatever was in the oven. Sans chuckled, pushing you off of him and heading to the kitchen again. He was doing something to it, back facing you, before he finally walked over and handed you a plate.

"Wait… are these…?" You picked up one of the little yellow bars looking it over. There was a light dusting of powdered sugar on top of it, and a certain smell was bringing back old memories.

"Lemon Squares. Bro found your recipe hidden away in between one of your cook books, so I decided to give it a go." Sans smiled as you looked at the lemon square, and bit into one of his own. You did as well, immediately getting hit with the amount of sugar used in these.

"Woah. No wonder I loved these." You laughed, biting a larger portion of the bar and being careful not to let crumbs fall. Once you finished the bar you wiped at your mouth, before kissing Sans on the cheek as he bit into his own. "Thank you hon, this is so sweet. Literally and figuratively." You laughed. Sans chuckled a little before finishing up his bar, and giving you a quick kiss on the lips.

"No need to thank me, its your day." He gave you a quick squeeze, and handed you another sweet bar.

"Don't mind if I do." You smiled, accepting the offer. Fuck it, it was your day.

.

So the shitty movies continued, though much like the first time you guys did this, your positions continued changing and eventually you ended up just laying on his lap for a long while, until your neck complained once more.

"So… Massage?" You asked, rubbing your neck and trying to get the cold pain out as you sat up. Sans's eyes lit up a little brighter.

"Of course!" He said, grabbing the blanket and laying it carefully down on the floor, along with the pillows for you. You got into your position, stomach down, arms to your sides, head on one pillow and the other on your rear. Sans quickly sat on the pillow, settling for a moment and getting comfortable, before dragging his fingers down your back.

"Mmm." You hummed, letting him know that he was off to a great start. He continued dragging his fingers this way and that, occasionally moving them independent of each other to cause the feeling to get even wider than usual. After a while, he started pressing in and making small circular patterns, slowly pushing the flesh on your back around underneath the tank top. His hands followed down your spine, hitting the sweet spot above you hipline, earning a quick hum from you as you relaxed even further into the pillow.

Sans's hands started moving back up, but the fabric of your tank top dragged up as well, causing him to pause and fix it. Well, that just wont do. "Hold on." You said, and Sans quickly lifted his hands from you. You loosely grabbed at the sides of the tank top and lifted your upper body, pulling the tank top quickly off. You dropped it to beside you and settled back down into the pillow, not thinking much of the action.

You couldn't see his reaction, of course, but it seemed like he hesitated before putting his warm hands back on you. They felt much better without the clothing in the way. He started massaging again, though this time it seemed much more deliberate, like he was focusing on finding the little spots that earned those little hums. He got very good at varying how he massaged, from simple circular motions to long dragging, occasionally doing slight waves with his fingers and making your nerves wig out. Last time it felt he just kneaded your back like dough, this time it felt like a proper massage. Like, the kind rich people would pay others for. Damn.

It felt wonderful. But, alas, your neck was still slightly tweaked. You quickly turned your head, hearing the loud pop, and settled back into the pillow. The hands on your back suddenly gripped tight at your sides, startling you and earning a gasp. The hands loosened before appearing next to your shoulders, Sans's ribcage pressing against your back. His breath blew some of your hair by your left ear, making you suddenly aware of how close he was. And how warm he was.

You froze, and for a solid second it was almost silent, minus the movie about two secret agents being married to each other and going to marriage counseling. Sans chuckled, taking a deep breath and pulling himself away ever so slightly.

"Sorry 'bout that, but I warned you. You really need to stop doing that." Sans said, voice ever so slightly lower than usual.

"Or what? You'll get a boner?" You punned, earning a moment of silence before Sans burst into laughter.

He sat up and leaned back, laughing a bit before it died off, and you felt him shrug. "Who knows?" That response startled you and curiosity started digging in your thoughts again.

You felt the urge to test him… Well, it is your day. You licked your lips, ready to see what exactly would happen if you didn't stop. You pulled your shoulders back, straining a moment before an even louder and a much more relieving pop was heard.

Sans's hands shook as the grip tightened on your back ever so slightly, seeming to be holding himself back now that he was prepared for that. "H-hey! What did I just say?" The shake in his voice had a hint of a growl to it. Damn, that was hot.

"You might get a boner if I did something like this." You replied, popping one of your fingers. The response was immediate, Sans's hands grabbed at your shoulders, weight shifting slightly on the pillow on your ass.

"A-as much as I… I don't know, appreciate? The popping, I don't know what… We've never… I don't want to go too far, okay? I never handled a human and…" He was so fucking sweet, gosh, you felt like you were going to have a toothache. But in the spirit of your day, you mentally said 'fuck it' once more.

"Treat me like a monster."

That startled Sans, and he was silent for a moment. "Are you sure? I'm not entirely sure how it'd feel for you."

"If I don't like it, I'll complain." You stated, excitement building. What was this going to entail?

"Okay… If it becomes too much, just say 'blue' or 'stop,' all right? Think blue stop signs. If you cant get that out, I don't know, just hit me or something." He seemed nervous, but you nodded anyway. He took a deep breath, though it didn't seem like he was as excited as before. Better fix that.

You popped your ring finger, and Sans's face immediately pressed between your shoulder blades. You heard him inhale, groaning against your back slightly.

"F-fuck, you always smell so good." A wetness appeared between your shoulder blades, making your eyes snap open. The wetness traveled up, lifting at the base of your neck, followed by a small kiss there. You swallowed, suddenly getting shivers. "Damn, you even taste good." He uttered, and the wetness appeared below your left shoulder blade. You looked at the pillow, and thanks to the mostly dark room you could see a slight blue glow coming from behind you. Sans was using his magic and making a tongue for himself.

He traveled lower, to the point where your ribs no longer protected your insides, and suddenly pressed hard with his tongue at the soft spot. You gasped, hands grabbing at the pillow at your head. "F-f-fuck!" You yelped, startled that it felt that good. Your nerves were going crazy on your back, making your twitch this way and that as Sans explored. He didn't respond to your outburst, instead traveling to the other side and doing the same, this time licking in a circle before digging for a moment, traveling up your spine. Your eyes fluttered up for a moment before you shut them again, taking a breath and trying to stop all of your twitching.

Until of course, you felt sharp pressures appear between your neck and shoulder, dragging across the muscles and nerves and making your vision go blurry for just a moment. Sans's teeth dragged until just before your shoulder, pausing a moment before the pressure increased. Some sort of noise escaped your mouth, what you would call it you had no idea, but Sans apparently heard it too.

The pressure let up, and you could feel a low chuckle come from Sans. "Sorry, I had no idea you tasted so good." He pulled back, allowing you a moment to get a few breaths of air back in you, before his tongue started traveling along the edges of your shoulder blades again. Each shiver and gasp you gave Sans seemed to energize him, and he responded by increasing the pressure from his tongue or the angle or something.

His bony lips pressed against the side of your neck, and out of nowhere all of your nerves exploded, and you felt him sucking. You opened your mouth as if to moan, but only a strangled exhale fell out, your sight dizzying you. He let go, and you suddenly dropped and inch and back into the pillow. You didn't even notice you lifted up in the first place.

The onslaught on your nerves continued for a bit, lick here, bite there, a few sucks in various sensitive spots that Sans had mapped out by this point. He was midway through a suck below your right shoulder blade when your grip on the pillow was just slightly too tight, and a pop was heard. Sans's breathing got heavy and his fingers dug into your skin.

"M-may I…" He started rough, and coughed to clear his voice. "May I try something with… your Soul?" He asked quietly. Your head was spinning as it was… what the hell would a Soul feel like? You nodded, obviously unable to say no when you were as curious as you were in this state.

Your chest got too tight, and the all too familiar feeling of your Soul leaving your body appeared. Though this time, it was pulled through your back, and nearly kicking the air out of your lungs. You took a few steady breaths, and felt Sans's fingertips carefully grab the Soul, and in turn, your entire being.

You could feel two massive fingers stroke down your form, causing you to shiver from the feeling. It happened again, and again, to the point you were having troubles determining if it was just your Soul he was touching, or if he was touching you physically as well.

And then something licked you, entirely.

You screamed, or gasped, you weren't entirely sure, but you most defiantly did something. You felt like your body was separating from itself, or maybe that was an effect of the soul, or maybe you just were feeling so much that you simply couldn't handle it. Everything in your vision was twisting and darkening and your body felt so good and there was too much going on… you only just started to register Sans's voice.

"-now, okay? I… I think that was enough for now, and I'm going to put your soul back in, okay?" You heard him ask, and a vague sensation of his hand pressed against your back became noticeable. There was silence, since you didn't have it in you to answer, and his weight slowly shifted.

Colors suddenly intensified almost to neon, sounds from the TV became noticeable, and you were aware of the air on your back.

You attempted to say something along the lines of "oh my god" and "holy fuck that was amazing" but you are pretty sure all you said was a long and droned out "oh."

"Are you okay?" Sans's beautiful voice asked from behind you, though you felt him get off of your rear. He sat on his knees beside you, resting a hand on your shoulder. You looked at him, a slow smile crawling onto your face as you nodded ever so slightly, suddenly very, very tired. You had no idea what time it was, but it was most defiantly not your usual bedtime.

Sans laughed a little, rubbing a hand through your hair. You blinked, and suddenly you were on your bed, no sense of the usual travel-sickness that you usually got when he teleported you. You decided not to question it, even if you could have, and managed to move slightly closer to Sans. He chuckled, bending down and giving a kiss to your temple.

"That was amazing. I hope you enjoyed your day, Vertebae." You smiled, giving weak nods. He adjusted himself to lay next to you, and you draped an arm across him. "And just so you know, it doesn't have to be a special day for that to happen. Just let me know." He gave another kiss to your cheek, and you let the calming darkness encircle the two of you.