Frisk and Sans were chilling on the couch while Papyrus was making dinner. Papyrus's phone rang signaling that it was Undyne calling for a sleepover. Pappy accepted and apologized to Frisk for leaving her with Sans for the night. "I would take you with me but uh, Undyne said she only wanted me to go over. I, THE GREAT PAPYRUS, PROMISE! THAT I WILL TAKE YOU TO THE NEXT SLEEPOVER HUMAN FRISK!!!" Frisk chuckled at his words, as Pap was so cute when he was innocent. Once Pap finished dinner, he served Sans and Frisk and left to Undyne's.

Sans was starting to get nervous as he and Frisk were alone. He was sweating and kept staring at Frisk. He loved the way she looked so relaxed as she ate her food in peace. He was still admiring her beauty when she looked him straight in the eyes, catching him off guard. "Is something wrong Sans?" the girl asked. Sans just shook his head as he felt his pants feel tighter, emitting a slight blue color in his crotch. He shifted in his seat a little while eating his food. All he could think about was Frisk. He wanted to do extremely bad things to her small, frail body.

Frisk had finished eating as she excused herself from the table, washing her dish and putting it away. She turned around to see Sans biting his lip as if to hold back a sound, and his face covered with a blue blush with sweat beading down his forehead. She looked at him in confusion, then shook it off as she went to take his plate when he was done eating.

Frisk was washing Sans' dish when she felt a pair of arms wrap around her waist and a body lean into her back. She felt his warm breath on her neck as he went to leave little kisses along it. She let out a small moan as Sans found her sensitive spot. Sans smirked against her neck and bit down on that spot hard enough to draw blood, Frisk biting her lip to hold back her moan. "S-sans, w-wh-what are you d-doing?" Sans just hummed against her neck, grinding on her backside a small bit.

At that moment, Frisk knew that Sans was in heat. She pushed him off of her so she could finish doing her chore. He whimpered and grabbed the dish and threw it at the wall. Frisk looked at him with a gaping mouth. "Sans! Why did you do that!" He grunted and hugged her small form, transporting them upstairs into his room. It was dark, and Frisk could barely make out the dusty treadmill in the middle of the room.

Sans threw her on the bed, her landing with a small thud and an 'oof'. He jumped on top of her and attacked her neck again, beginning to slowly rub her hips and her thighs. Frisk gasped at the touch of her sensitive inner thigh, Sans taking that as an opportunity to kiss her roughly, shoving his tongue in her mouth. She was still for a second, before being knocked out of her thoughts, eventually kissing Sans back. Their tongues fought for dominance, Sans winning of course. He explored her cavern, tasting and feeling every inch of her mouth. He sneaked his hands under Frisk's shirt, seeing that she wasn't wearing a bra.

"Hmm, what's this? You're not wearing a bra?" Sans teased as he groped her breast with one hand, the other hand running down to her thigh again. He looked down at her lustfully, his left eye now glowing that light blue. He then lifted Frisk's shirt over her head and threw it somewhere across the room. He kissed Frisk again, leaving kisses down her neck, and chest then took a breast in his mouth. He sucked and licked on the hardening nipple while groping the other. This caused Frisk to slightly gasp and moan his name at the pleasure. Sans smiled and went to leave more kisses down her stomach and abdomen area, then stopped at her pelvis. He carefully tugged at the sweats she was wearing as if asking for her permission to do so.

Frisk nodded and Sans slowly pulled down her bottoms. He began rubbing the inside of her thighs as he left, once again, more kisses. He got back up to kiss Frisk. He swiped his tongue across her bottom lip and she denied, teasing him because all he was doing was teasing her. He began to rub her in between the thigh area, making her gasp and him shoving his tongue into her mouth again. This time, he was rubbing her outside her panties, Frisk was a moaning mess. Sans broke the kiss and sat up, admiring Frisk's beautiful and small body. She sat up as well and started playing with herself.

Sans got off the bed and pulled Frisk with him, putting her on the floor. He then sat on the edge of the bed in front of Frisk. He grabbed her head and put it next to his crotch, the blue color stood out now. Frisk immediately knew what she had to do. She unbuttoned his shorts and pulled them and Sans' boxers down and his glowing member sprung out. She looked at it wide-eyed as Sans groaned from the sudden pleasure of his dick being released from the prison of cloth and fabric that was restraining it.

Frisk grabbed his member and started pumping, Sans groaned loudly once again at the pleasure. He thrust his hips upwards and into Frisk's face, she dodged his attempt to fuck her mouth. He then started mumbling little curses as he pulled his shirt over his head, throwing it somewhere.

Sans was getting close to his climax. His dick was twitching like crazy and he was grunting and groaning as he watched the girl pleasure him. "O~oh shit... F~~risk, I-I'~mmmm" the skeleton said as he was about to release. He was ready for another groan to finish it, but Frisk cut him off by stopping what she was doing and putting her finger gently over the tip, leaving Sans panting and whimpering for more. Frisk smiled at him as she bent down under the bed, grabbing a pair of handcuffs. Sans just smiled at her as she cuffed his hands to the bed frame. She then got on top of him and took his member in her mouth, making Sans let out another loud groan.

Sans was back to panting and groaning again as Frisk made him feel good. She took in every inch of his long shaft, gagging a little bit but shrugging it off. Sans began to thrust into her mouth, gasping and panting her name. Frisk moaned in pleasure as Sans was cursing his mouth off at her. Sans eventually came in her mouth and she swallowed all that shit.

Frisk got on top of Sans with his face positioned at her opening, signaling for him to work his magic. He stuck his tongue out as she lowered herself onto his face, shoving it inside her the best he can. Frisk's hold tightly grasping Sans' slimy blue muscle created moans to erupt from both of them. Frisk's walls soon tightened around his tongue as she came on his face. Sans licked it up and Frisk went down to his throbbing dick. It was standing erect and twitching, ready to release. Frisk gently and slowly lowered herself onto the appendage, teasing Sans' tip with a little rub.

Frisk moaned silently as the tip entered her, stretching her walls with a burning feeling. Sans thrust upwards, shoving his entire length inside her. She let out a loud moan/scream and tears sprung in her eyes. They stayed like that to let Frisk get used to the feeling. A few minutes passed by and Sans tried to do a test thrust but Frisk had slammed down on his dick, making him groan aloud. They started at a low pace, the room filling with their slight moans and grunts.

Frisk eventually started to feel a knot in her stomach. She undid the handcuffs on Sans and let him take over. Sans immediately grabbed her hips, leaving bruises most likely, and flipped them. He started thrusting into her at an inhuman pace. Frisk's knot about to explode, and Sans' thrusts became sloppy as Frisk was basically screaming his name as she came on him for the second time, Sans finishing with her at the same time. His warm liquids filled Frisk and he pulled out, collapsing on top of her as they were both a panting mess. They cuddled into each other as they exchanged their "I love you's" to each other.

~THE NEXT MORNING~

Frisk had woken up with a slight pain in between her legs. She went to the bathroom and drew up a bath, getting into the warm water as she relaxed her aching muscles. She heard the door open and a naked Sans walked in and got in the bath with her. He hugged her close as she was relaxing in the warmth.

When they got out 15 minutes later, they went downstairs hand in hand only to meet an angry Papyrus. "WHY ARE THERE BROKEN DISHES ON THE FLOOR SANS?! LOOK AT THIS MESS!! DID YOU GUYS THROW A PARTY WHILE I WAS GONE! IT'S A MESS!!!!!" Papyrus's loud voice caused Frisk to flinch, as she didn't like loud noises.

Sans spoke up, "May these dishes rest in 'pieces'." This pissed off Papyrus even more as he stormed out of the house and started running out in the snow. Frisk and Sans just both laughed as they went to clean up the mess they had made the night before. Sans went to grab the broom and dustpan and Frisk went upstairs to strip the sheets off Sans' bed to wash them.

Le tiem skip

Frisk was taking the laundry out of the dryer when she felt a pain in her lower abdominal area. She cried out and accidently dropped (threw) the laundry over the railing, watching as they landed downstairs on Sans' head. He rushed to her side. "Frisk? What's wrong???" He saw a (f/c) soul inside Frisk and started crying. Frisk looked at him with worried eyes and asked "What's wrong Sans?" He showed her what he saw and she had tears in her eyes as she was wondering 'WHAT? IS THIS EVEN POSSIBLE???'

They both sat there pondering the fact that they're going to become parents, happy as can possibly be.