Undertale Lemons

Tf you doin in my swamp

This is uuh Sans x (Aged up) Frisk
And it's a lemon. I suggest if you still need your parents permission to go on club penguin, go read something else. This isn't for you.
I am reacting to this lemon the same time you do because I haven't read it over.

Enjoy your lemonade.

Rolling over slowly, she nestled her face against the pillow pressed against her. It had been a peaceful night, her and Sans deciding to take an easy night for once as he said he wasn't feeling too well. It wasn't until it was around almost midnight that she felt a rustling next to her, practically ripping the sheets off the bed. She knew it must be Sans, he always did that whenever he went to the bathroom in the middle of the night or just couldn't sleep.. but the atmosphere felt so different now. She felt as if someone was standing over her- no, towering over her, as she laid there calmly. It wasn't until she finally opened her eyes that she saw Sans just standing there still. Sitting up slowly, she rubbed the sleep out of her eyes as she stared at him for a moment.
"Sans?.. Are you okay?" She reached up, brushing it against his cheekbone. Though, he didn't respond to her like he normally did. Instead he grabbed her by her shoulders and pressed her back down against the bed. There was a few moments of silence until he grinned, showing off much sharper teeth that hadn't been there before. His tongue hung out in a long lewd way as he began to pull down the waist band of his shorts to show off a more tentacle appendage than she was used to.
"S-sans.. you're being weird. Is this some weird thing you wanted to try?.." She chuckled nervously as her hands were moved to wrap around his shoulders as he nestled himself between his thighs. Sans just chuckled once more, biting harshly at the sides of her neck leaving marks down to her shoulder. One quick nip was hard enough to draw a bit of blood, this made her hiss out a slight whimper but this didn't seem to make him stop. In a thicker tone that she was used to, Sans growled out.
"I want to make you mine. In so many ways I've never done before. I want to make sure from now on, every monster- fuck, every human, will know that Frisk belongs to the fucked up bone head Sans." He mumbled into her breast, nibbling around the edge of her nipple only to let his tongue flick heavily against the very tip of the hardening bud. Arching her back with a mewling moan, she gripped the sheets underneath her. The assault of his bites didn't cease as they traveled down her stomach, nibbling at her hips leaving a mixture of hickeys and harsher bites. They made a trail down to her thighs where they paused just to graze for a moment against her clit. Frisk gripped at the back of his skull, her nails digging in as her whole body shook.
"S-sans what has come over you?.." She mumbled, her eyes half lidded with desire. She had never wanted him as badly as she did at this moment. He looked so monstrous, sinister, but he was still her Sans. Just in a whole different way. She expected to feel the warm embrace of his tongue, yet she felt nothing. He instead was moving her legs to rest on his shoulders, position her to have her hips resting up to expose her entirely to him. Leaning down, he kneeled to angle the tentacle appendage to her entrance which seemed to squirm with it's own accord. Instead of the normal slow and tenderness, he positioned the tip in before slamming his hips quite forcibly down into hers causing the whole bed to creak loudly. Before she could moan out, Sans covered her mouth firmly.
"Papyrus can't hear you. But if you really want me to hear you, you'll have to do it extra loud.. Make it bone rattling." He grind his pelvis against hers, enjoying the pleasurable feeling of his bones against her softer skin. Even during the roughest moments of his personality, he still made a pun. She couldn't believe it, but she also could as it was still her Sans. Though right now, Sans was working on making even the furthest reaches of her all his. As the harsh pounding began, she began to lose herself in the pleasure when she noticed something. She felt another pressure against her other rarely used hole.. he had split his appendages in two different freely moving tentacle dick. It prodded against her anus until it finally managed to slip in very slowly, and quite thankfully to Frisk that his appendages were already so slick it made insertion easy. It took her some time to accommodate to both thrusting at the same time inside her as her hips rocked back and forth. The odd and unusual feeling slowly became addicting, her hips shaking as her muffled moans hummed loudly against his palm.
Sans was huffing and panting harshly, the stimulation from each hole was almost mind numbing but he had to continue his assault on her body. He had to make sure that her body was thoroughly, even the bruises and bites wouldn't be enough. Even as his hands gripped her hard at the thighs, it seemed like she might melt away with how warm she felt on the inside. He thrust harder, bucking her at an unsteady pace as he began to feel the familiar pressure building up at the base of his cocks. Frisk was moaning louder and louder against the palm his hand until it could barely hide her pleasure anymore. Her thighs shook beside his head as she gripped the sheets so hard they began to rip.
San's moved away his hand just to her her sudden gasping, practically yelling moan as his erratic thrusts rippled through both holes. She reached up to grip his ribs instead of the sheets, practically pulling his face down for deep kisses as if to contain her own moans. Suddenly San's voice became more erratic, moaning loudly in her ear.
"G-god I love you.. You're so fucking tight around me. You keep pulling me in as I pull out, how the hell are you this sexy?.. God I want to cover you in my cum." He was sweating profusely as he kept slamming harder and harder, Frisk was barely able to keep up in as her mind began to drift to her own orgasm. She grasped the sides of his head, resting her forehead against his a moment to steady herself.
"Do iiiit... please! Mark me as yours!..." She moaned, the final bounds of her orgasm hitting her as her body clenched up in her final release. It took Sans a few more pumps of his hips, but when he pulled out he let his load from bother appendages coat her. From her breasts to her ass, he made sure to sufficiently coat her with huffing pants. Collapsing beside her, he curled his fingers in her hair as his sharp teeth remained still along with the appendages.
"...S-so.. When are those going away?.." She mumbled, holding onto his hand softly with a softer grin. She curiously looked down at the dual cocks which seemed still very active. He nestled against her neck, making a fresh bite mark along her collarbones.
"Well, seeing you coated like this isn't doing much to make the bones settle.. I'm always up for round two." He winked at her, scooping her up into his arms to carefully guide her into his lap. She snickered softly, kissing along each of his phalanges only to suck on the very top of one.
"I'm always up for another round with you.." She winked back, keeping up the flowing mood. With that, he eagerly carried her to the bathroom with a larger grin than before.