#underfell self insert

meeting the parents!! :3

(Underfell Sans x male reader SMUT)

Warning: May contain NSFW/Smut acts, blowjob(?), slurs, aka "bad words", pulling hair kink, masochism mentioned...

Basically Reader sucking off Red

>Y/N= Your Name

>L/N= Last Name

>Y/C= Your Color

With all that cleared as the anti-void.

We're beginning!

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It was a really cool day in our so beloved Snowdin, whoever, it's not the sweet and comforting Snowing that you are thinking, no, I'm not talking about Undertale's. I'm talkin' about Underfell's. That AU where everyone is a prick except for a dummy flower and two silly humans.

Those humans we're mumbling about are Frisk and Y/N, two siblings who where exploring a mountain and "accidentally" fell to the underground world.

They made their way through it, sometimes easier, sometimes harder, but at this day it is what they call "Home".

But, we shall stop talking about humans and monsters and all that bullshit, right? You wanna see a skeleton fucking a human. Well, let's get into what happen

As I said earlier..

It was a really cool day in our so beloved Snowdin, winter always hitted hard back there and made everyone stay at their houses for ages because if you dared to step outside you would automatically froze to death.

And that's how it came to a house owned by two skele-bros, under the name of Papyrus and Sans around there and under the names of Cherry and Fell/Red around the other AUs. In the house there were also a human. Y/N L/N. A young-adult male human, with Y/C hair and beautiful Y/C eyes, such a handsome boy I should say.

Everyone was at the living room, seated in some comfy yet destroyed sofas, warped with blankets around the fireplace, everything was so calm, weirdly, so calm. But, you seemed to like it, just being there with your boy, sitting in his legs and warming him up with your arms on a cold day.

Yeah...that was until Frisk called Cherry almost panicking. He answered the phone and started to talk to the other human while you two were looking confused at his expressions of fear. As Frisk said something bad happened to the Emperor/King (aka Asgore), due to some weird potion Alphys tried to make and fail, in resume, it was an accident, but Papyrus needed to attend it as well as the little human. Leaving the house for you two

You wanted to do the same as you were doing, nothing. But, Sans had other plans for you today, and you were no one to complain about your lover's commands.

He lifted you from your legs and started to carry you upstairs, you made a confused and surprised noise and quickly warped your legs around his hips so you wouldn't fall. That surely made him laugh.

He opened the door of your shared small bedroom and pushed you to the bed, almost making you fall in the process, but that didn't matter. What matter at that point was he, and only he.

He started to make a line of "kisses" in your neck, to make it more "romantic", you blushed a bit at that since he almost never attacks your neck so gently.

You watched as he moved from near you to practically the edge of the bed, you confused left out a noice as if you were asking why did he do that.

If you asked that instead of just making a noice, it would have been called an answer, but since you didn't, you can just call it "a hint".

What am I talking about? Well, he, "out of nowhere", pointed at his (made by magic) hardened red cock. You looked at it for a few seconds, then back at him, and what you saw was something new for you.

You saw him, looking shamelessly at you, with red blush painted in his cheeks and asking you with his look to take car of his "little problem"

You smiled sideways and got yourself at your knees on the floor in front of the other's male clothed dick. At this point you were wondering if you would be able to enjoy the alone time at home without a dick in your ass.

For your like,

He already putted a condom on his non-existent shaft, just for safety and so he wouldn't have to clean you and the floor later, you know, lazy dogs are the worst (best).

So with that settled up you started slowly, starting to massage the torso of it. Giving tiny kisses at his tip and even a few licks here and there. While you were at your work, you could hear him mumbling cursed nothings like:

“Fuck, y-you do know how to...ngh...do your work-ah~”

“Keep going little pup” While taking deep breaths

“Look at that,... you look a-amazing like ah..this~”

In resume, he was a groaning mess with a little bit of moaning. You know? Bitches can't get themselves shut.

After giving it a well done massage you guessed that it needed a bit more of help. Just a guess, right?

Hell yeah

You asked him to sat down on the edge of the bed so he wouldn't tremble when you started what you (and I) have in mind.

So when he did, you finally took like half of his length on your mouth, like the tip was aggressively touching your throat, threatening to left you without air and gagging because of the feeling of it. He noticed that and, against his desire, he pulled back a bit so you wouldn't choke yourself.

You silently thanked that and slowly began to move your head up and down on him. Making Fell's "mouth" leave a little surprised moan. It was so small, that if you weren't paying all your attention to his face and/or expression you wouldn't had noticed.

You kept going faster as the time went by, just pleasing your skele-boyfriend. And time to time you would stop sucking him to give it a few licks or even kisses, whatever you wanted.

As you were growing curious, you asked him if you really could do whatever you wanted. You know that you are still his puppy, right?

For your likely he said “whatever, just...don't stop” so it was a green signal for you to continue

You looked at him a last time before looking at his cock, you slowly pulled it closer to your mouth and "out of nowhere" bited it. Not hard enough to make him feel such pain but enough to make him moan loudly and look at you with a... Surprised? Angry? Blushed? Shamed? Face, I don't know how to describe it, but he was all red and was opening and closing his mouth in an attempt to say something.

You giggled at his reaction and that he actually moaned quite loud and began again to suck him, but more than sucking you were like face fucking yourself? I mean, you were pulling his dick in and out of your mouth, making his length go even further than at the beginning and sometimes making you gag, but you wouldn't care less, all you wanted was for him to cum.

He took the strings and started to buck his hips along with your movements, pulling your hair roughly for you to take more of him, damaging your throat a bit, making you moan against his dick. He noticed that you liked it and started to buck his hips even faster and pulling your hair back so your head would fall back.

Starting to see blurry because of the pleasure (pain) the only thing that you actually could see was Fell's smirk looking down at you with those hungrily red pupils, calling you his pup, his bitch, his whore, his and only his.

And then, when you sucked hard on him for the last time, was when he came in the condom. As you felt he already came you stopped and pulled him out. Facing him and "kissing" each other before he slapped your ass cheek and you giggled.

“Aren't you gonna help me get this off, bitch?” Referring to the condom filled of his juices, which not so surprisingly were red.

“Yeah yeah, human service is here” You joked around and helped him

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Hello good pal, how are you? 😸

I wanted to say a fun fact, and is that Underfell Sans is one of the Sans less liked by me and yet is the first one that came to my mind while I was trying to figure out which Sans I was gonna write for first

So yeah, enjoy this little, not so little, thingy Fell lovers<3

Ahhh thank you! I'm glad you like how I write sans ^^

Have a sketch since my mind is buzzin too much right now with many ideas-

I'm about to ruin this man's whole reputation >:3