Chapter Text
Frisk woke up feeling sore all over, and not in a good way. Water cascaded around her and a paper bag floated by as she groggily sat up and rubbed her head. It was a feeling of deja vu as she found herself resting in a flower bed of golden buttercups, her fall miraculously not killing her as she looked up into the murky darkness, not even able to see where she had fallen from. With a groan of pain, she managed to stagger to her feet and gauge her surroundings. Looking around, she found she was in the middle of a dump, piles of discarded trash increasing in size and amount further in. Not able, or even willing to go back the way she had came, Frisk set out in this new direction. Most of the trash piles were nondescript mounds of unidentifiable rubbage, but what she could make out seemed oddly human. Old porn mags, used condoms, a few discarded sex toys, and the occasional box set of anime DVDs. It seemed like most of this stuff had washed down from the surface, and Frisk remembered how most monsters only recognized humans from porn. She reckoned this must be where they found it, the dump likely being a rite of passage for developing monsters to rummage through for fap material. Frisk wandered the dump in ankle deep water, carefully sidestepping the piles of garbage. She managed to find a surprisingly intact cooler and found a stash of Astronaut Food inside. She recognized it from the planetarium the schools in town would drag everyone to, and she wasn’t surprised to see them thrown down here. But while they tasted bad, Frisk needed some food that wouldn’t make her orgasm and so she scarfed down the human food quickly, her hunger finally sated as she had eaten far more cum than than actual food in the past few days.
Feeling better about her situation, Frisk was nearly out of the dump when she saw a familiar sight. A dummy sat abandoned in the dump, its body lumpy burlap that ended at a dildo grafted onto its lower torso. It was just like the one Frisk remembered FLIRTing with in the Ruins, having straddled its dick and kissed it before Toriel had made her stop. Frisk walked past it before hearing a scraping sound. The human turned around to see the dummy looking at her. It seemed…mad? The dummy suddenly began levitating and flying around in the air, smacking against Frisk and pushing her away from the dump’s exit. “Foolish, Foolish, FOOLISH!” The dummy seemed red with anger, its dildo cock throbbing an angry shade of crimson as the Mad Dummy floated in the air. “I am a ghost that lives inside a DUMMY! My cousin used to live inside a DUMMY, too. Until…” The Mad Dummy knocked Frisk over, sending her bag flying into a pile of trash and landing the human on her ass in ankle deep water. “YOU CAME ALONG! When you began hitting on them, rubbing their crotch and kissing their neck, they thought they were in for a good time…but then you just left! You gave him the biggest case of blue balls the Underground has ever seen! They had to leave their body just to escape the pain! Horrible, despicable!”
Frisk tried to sign her apologies. If she had known the dummy in the Ruins was a monster she would have most certainly stayed to finish them off, but the Mad Dummy wasn’t having it. Instead, Frisk found her skirt magically lifted up, revealing her still pantyless crotch for the dummy to line up his angry silicon dick with. “I’m going to fuck you the way my cousin deserved to do to you!” With that the dummy plunged into Frisk and began to fuck, overwhelming the human as she was taken in the middle of the dump. It wasn’t the first time she had been fucked in such a filthy place, but it had certainly never been this weird. The ghost possessing the dummy fucked her hard, his thrusts more out of anger than lust. Still, Frisk quickly adapted to her situation and decided the quickest thing would be to get him off so she could escape. And so she lifted up her sweater and bra, flashing her yellow boo-bies to the ghost to get him to finish faster, the sight of big bouncing boobs better than any waterlogged porn mag the dump had to offer.
The Mad Dummy wanted to hate the human, but he couldn’t. Her body was too damn sexy. Her slutty pussy wrapped his dildo cock like a blanket, swallowing it up with practiced ease as Frisk had experienced far worse. Her rack shook with each thrust which only encouraged him to fuck faster and Frisk moaned as she sucked on the Snowman’s carrot she kept in her bag, choking herself on the makeshift dildo as the ghost (and a distant Snowman) both shuddered in pleasure at the slut’s wet body. The Mad Dummy felt his body approach something. His spirit felt hot and he began to feel his body even more. Every surface, temperature, and sensation became more real and with his now truly possessed cock he shuddered and yelled “JESUS FUCK!” as he had a dry orgasm, his body shivering as the sheer amount of lust finally allowed him to fuse with his body, Frisk slowly slipping him out of her as he came down to rest in the dump. “Woo, that was…wow…” The dummy seemed inexplicably out of breath as Frisk pulled her clothes back down and slipped her carrot back in her bag. Turning the corner came the pale figure of Napstablook, the ghost looking at his cousin finally fused and the familiar sight of the human from the Ruins. “Ohh, it's you…”
Frisk followed Napstablook away from the dump, waving goodbye to the dummy as the ghost led her through a quiet area to his house, a blue ghost shaped building right next to a similarly shaped pink one. “Welcome to Blook Acres I guess…” the depressed ghost said, drifting over to what looked like a racing track which had snails milling about. “I would normally offer racing, but it’s breeding season for the snails so they’re busy…” Frisk waved her hands in understanding, not wanting Napstablook to feel sad at being a bad host. The ghost floated through his front door and Frisk nearly walked in after him before realizing that would mean walking face first into wood. She turned the knob and walked inside. The room was sparsely furnished, wooden floors dusty having not been stepped on in years and cobwebs filling the corners, one of which held an advertisement for a spider bake sale. A fridge hummed in the corner next to a boxy TV set, and the corner held Napstablook’s computer which seemed to be the only thing well used in the room. Frisk typed on her phone to talk to Napstablook, asking what he did for a living. “Living?” Frisk adjusted her language for the ghost and asked what his hobbies were. “Oh, I make music. Here, let me put some on.” Napstablook manipulated the computer to begin playing a spooky tune which warbled and bounced along and Frisk faked interest in the frankly unimpressive music as Napstablook hovered. “You hate it…” Frisk shook her head no, wanting to be polite but failing to convince the ghost who sighed and began floating closer to the floor. “I’ve been wanting to transition out of music, but I don’t think I can…” Frisk asked Napstablook what he wanted to do, and he sighed while laying down on the floor and turning over. “I’ve been thinking of doing ASMR, but I can never get in the mood…”
Napstablook sighed once more in depressed defeat as Frisk considered. Napstablook would be good at doing some sexy ASMR, his voice was low and gentle and he had some pretty good audio equipment. Remembering the ghost possessing the dummy, Frisk reasoned it was possible Napstablook just couldn’t get in the mood because he lacked physical sensation. Frisk offered to Napstablook to possess her for a bit. After all, she had one of the most horny bodies she knew and if the ghost couldn’t get in the mood with her tits and ass attached to them then she doubted anything would work. Napstablook thought for a moment before drifting over. “I guess…it's worth a try.” Frisk laid down on the floor and let Napstablook settle down onto her, cold ectoplasm seeping through her skin as she focused on breathing. The world began to feel vast, the cosmos swirling around her as gentle music flowed through her. She could feel every part of herself. No, she could feel every part of the room, the earth, the universe. Every tingle of desire, every scintillating breeze, every fiery star. Her body felt cold and hot, she sweated and shivered as Napstablook let out a moan deep within her mind. Her hands, possessed, flew to her body and groped her own massive chesticles, kneading warm flesh as her toes curled, experiencing overwhelming sexual pleasure from the perspective of someone touching themselves for the first time ever after years of abstinence. The world was too vast, her nerves too raw, the pleasure too great. Frisk let out a deep guttural moan as her body bucked upward like a horror movie, her pussy squirting across the room to hit the far wall as she climaxed to the feeling of the universe, everything getting her off as she silently screamed in ecstasy from the ghost assisted orgasm. She collapsed back onto the floor, the cosmos shrinking back down to her own senses as Napstablook floated out of her, breathing heavily and looking a bit happier than before. “That was…amazing…” Frisk shuddered and groaned from the aftershocks of the hardest orgasm she had ever experienced. Napstablook seemed to have enjoyed the experience and while he was still shy and timid, he seemed more invested in his work and he began brainstorming ideas for ASMR audio. “Boyfriend? No, maybe daddy…neighbor, that’s a good one…” Frisk dragged herself out of the house and stood on wobbling legs after ten minutes of recovering. She thanked a distracted Napstablook for the good time and set out to the east on shaky legs.
The caves narrowed back down into a single corridor and after a few minutes of walking, Frisk found another Dimensional Box. She offloaded some stuff such as the Abandoned Quiche and a spare Astronaut Food before she noticed the box was set up next to an entryway to a smaller cave. Frisk entered and found an old turtle looking monster sitting in a shop. “Hehe, hey there youngster! My, my…” He held up his magnifying glass to ogle the human slut’s impressive cleavage “Ooh hoo hoo, what a lovely specimen we have here!” Frisk tried signing and Gerson responded in kind while speaking. “Been a while since a human came through these parts! Last one was a bit of a wild spirit.” “ You’ve met another human? When? ” Frisk signed. Gerson chuckled and scratched his head. “I can’t quite remember, time gets away from you after a while. Was it, a decade? No, a hundred. Ah some numeral of ten. She was about your age, no, a bit older. Sorry, the rack threw my estimation off. Had her nose buried in a book when she found me. She was rather interested in my, hehe, experience.” Gerson licked his lips and Frisk spotted what looked like a collection of human clothes resting on a shelf. They seemed nerdy yet oddly Frisk felt their wearer likely had a hidden pervert side if she had gotten this far in the Underground. “ Can I buy some of her old stuff off you? ” Gerson laughed and eyed her up and down. “Even if you were her size, I wouldn’t part with my old sugar baby’s delicates. But, I may be inclined to trade some of their old possessions for a little suck and tug hehe.”
Frisk didn’t normally go for older men, but Gerson was a monster so the sex was guaranteed to be good. Plus, if the previous human had chosen to stay here and confine herself to a single partner it must be good. Frisk slid off her sweater and unclipped her bra before kneeling down in front of the old archaeologist turtle. He rubbed her head as she unbuckled his belt for him and pulled down his pants to reveal his throbbing cock. Frisk gasped as a heavy cut of meat slapped her face, drooping over past her head as she breathed heavily on it. God he was big, and Frisk could instantly tell what could possess a girl to become the turtle’s personal sex toy. She kissed and licked his old wrinkled balls, feeling his shaft harden on her head, its tip oddly bulbous and Frisk could tell it would be hard to pull out once it was in. Frisk began to kiss along the underside of Gerson’s dick, slathering it with spit and kisses as she made her way to the head, having to physically shift her kneeling position back having misjudged the old man’s size. Gerson didn’t seem interested in her mouth though and angled his cock down before plunging into her bosom. Frisk squeezed her tits around Gerson’s cock as he titfucked her, her eyes looking up at him with batted eyelashes to try to improve the experience. Just as he was about to finish, he pulled out and said “On the table,” in a low, gravely voice. The dominant command sent a shiver down Frisk’s spine and she hurried to bend over the shop’s desk and presented her thicc cheeks for Gerson to slap and grip before he slid his warmed cock inside her. The turtle dick struggled to be taken in at first until the tip was in and Frisk groaned as her ass was humped by the horny old turtle, yellow flesh jiggling and shaking with each thrust as Gerson fucked her to completion, letting out a grunt as he filled the human slut’s ass with his thick, chunky cum, Frisk moaning in visceral pleasure and disgust at the decades old spunk filling her insides. Gerson wiped his head with a towel as Frisk rearranged herself and the old shopkeeper handed her some of the old possessions of his old sugar baby as agreed.
[Nerdy Glasses & Smut Journal Acquired]
Frisk tried looking through the foggy glasses, the old plastic so difficult to look through she was practically blind, the accessory hiding her eyes like in an anime or hentai in thick round lenses. She slid them into her cleavage for safe keeping and flipped through the Smut Journal. It was filled with veiny, vividly drawn cocks, some resembling that of monsters while others seemed to have come straight from a pervert’s imagination. Notes scrawled the insides, words like lewd, cum, thick, nasty, and every other potential smutty word being bolded and jumping out of the pages. It seemed like a mixture of real recollections while other entries seemed to be wet dreams of a horny slut, the line between them impossible to determine. Frisk would have fun flipping through the pages later and she thanked Gerson before traveling further through Waterfall. She passed by another stretch of waterfalls, having to trudge through thigh deep water which she only did after taking off her stockings and holding them and her bag above her head. She found herself in a dark forest, bioluminescent trees towering into unseen dark ceilings and glowing mushrooms lighting faint trails through the vast dark cave, weaving past stalagmites and rocky outcroppings to the other side. Frisk walked through, admiring the silent beauty of the underground forest as she walked along. The Underground may not have the sun, she thought, but it has its own beauty.
Behind a tree, a monster spotted the human girl walking along, the story of its cousin in the Ruins suddenly not seeming so far fetched. Frisk paused at the sight as a jello mold monster unwrapped to its full form, Moldbygg standing over her in chaste pulsating silence. Frisk tilted her head, wondering if the monster wanted to fuck her. Slimes however, pushed the limits of monsterkind with Moldsmals being the closest to a female the Underground had. Moldbygg, unlike her curvaceously attractive cousin, was not actually in the mood for physical sex. She had a libido of course, but she was content with her toys and found the concept of even hugging another being uncomfortable. It wiggled and made slime sounds to roughly convey this idea to Frisk, who already having an abundance of dick to choose from, was respectful and stood a good distance away. Moldbygg seemed thankful for this and Frisk sat down next to it while showing her newly acquired Smut Journal. The monster and the human both pleasured themselves next to each other while each silently reading from the wet fantasies of the book, the page she had randomly opened to being a smutty fanfic of a popular game where every encounter was rewritten to be sexual. It wasn’t that good, but it was rather explicit, and Frisk found herself cumming on her carrot dildo while next to her Moldbygg gurgled in similar climax. Frisk shut the book and bowed to Moldbygg, maintaining her personal space as she made to set off. Moldbygg, thankful to finally run into someone respectful of her preferences, wanted to thank Frisk for hanging out with her. She wiggled in a direction south of the forest, a dark path leading to an unknown destination away from the main road. Frisk thanked Moldbygg for the tip and followed the path south.
Gems reappeared in the ceiling and Frisk came out of the dark forest to find herself in a small village. A sign at the beginning in broken English said “hOI!!! welcom to… TEM VIlLAGE!!!” Another Dimensional Box rested against the far wall and milling about a statue were a bunch of Tems, weird, cat looking things that perked up at the sight of Frisk. “hOI!” one said and Frisk guessed this was going to continue. The Tems gathered around staring up at her. “Uwa! So sexmy! So cute!” The Tems seemed shaking and eager to feel and grope the slutty thicc thing that had walked into their village, but as one touched her leg their skin puffed up. “Allergic!” they yelled and the Tems lamented their human allergy. Frisk felt bad for the poor monsters before having an idea. She reached a hand in her sweater and expertly unclipped her bra and pulled it out for the horny Tems to see. Wrapping one hand in her lacy red bra and with her other covered in her satin pink glove, Frisk sat down and began offering handjobs to the horny Tems of the village. A line quickly formed and the small cat girls walked up before lifting up their oversized shirts to reveal small, girthy white cocks which Frisk eagerly stroked in her gloved hand and pumped with her bra hand. “Uwa! So much cums!!!” The first Tem moaned and shot their load, hitting Frisk straight in the face as the other Tem getting a handjob cummed a few seconds later. Frisk jerked off the entire village, the final Temmie shocking her as their moan was a deep guttural groan and shot three times the load onto her hand, staining her bra. “Sorry, I’m Bob.”
Entering the Tem Shop, Frisk found another Temmie. She was a bit different from the rest, her hair grey instead of black and done in a different style and her shirt was striped rather than solid. “hOI! welcom to, da Tem Shop!” The store was rather sparse with most of the items being sold being rather useless scraps of paper. Temmie hopped in her seat and said “I need da muns for colleg!” Frisk realized that if Temmie was to keep selling these items, she would never make enough money. And so, she decided to teach her something monsters would really pay for. “Huh, wats strippers?”
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Frisk and Tem twerked on the table to the wows and uwas of the horny Tem village. Money was being thrown at the table as Frisk’s cheeks clapped together in loud meaty slaps while next to her Temmie similarly threw her furry white ass back, her fuzzy cheeks wrapped in a tight yellow and blue thong that disappeared into her crack and made her ass look nicer as she was amazed at the amount of money being thrown at her. “Uwa! I can gos to colleg now!” Frisk got down off the table and gave Tem a good smack on her ass, leaving a long lasting red mark as her handprint became outlined in hives from the allergy. Given Tems’ allergies, this was Frisk’s best way of getting the horny monsters off and Frisk promised to visit Tem village in the future once Tem was back from college. Leaving behind the now Tem Shop & Strip Club, Frisk re-entered the dark forest before finding the main path again, leaving behind the sound of clapping cheeks and horny little gremlins.
The hallway was dark and long, steps echoing off of the walls as Frisk approached a glowing blue echo flower at the end. “Behind you…” it whispered and Frisk whipped around to see Undyne standing twenty feet away, glaring at her in dark armor as she stomped forward. Frisk thought she was done for until Willy the Monster Teen burst out of nowhere. “Oh my god Undyne! Frisk, Undyne is here wow!” Willy looked between the two women, oblivious to the tension going on. Undyne paused in her walking, glaring at Willy. She grabbed him by the collar of his shirt and dragged him off, leaving Frisk to quickly run away. There wasn’t much Waterfall left, she could feel the humidity going down and the caves becoming larger. On the wall before a rickety bridge, a glyph could be seen that Frisk took a moment to read. A Delta Rune inscribed above the words showed two round orbs that reminded Frisk of boobs, with wings extended and three phallic looking triangles resting below it. “ There is a prophecy. The Angel... The One Who Has Seen The Surface… They will return. And the underground will go empty. ”
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Frisk’s eyes fluttered and her mind was flooded with another vision, a horrifying vision of uncontrolled lust.
The vision bounced up and down, groans emanating from the piles of bodies around the viewer. Frisk could see the drained and broken bodies of the monsters of Snowdin, the losers of an orgy taken too far beyond what they had asked for. A grunt came from below as the view shifted down to see Papyrus. How the skeleton was having sex was out of sight, but the royal guardsman moaned and the sounds of bitchy laughing filled the vision as the selfish slut made every monster’s balls go empty to satisfy her own lust.
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Coming back to her senses, Frisk leaned against the wall before hurrying onward. She ran across the bridge, turning back at the sound of someone yelling “Yo!” Frisk turned to see Willy on the bridge, breathing heavily as he had run here. “So…uhh, Undyne said you were…uhh, she said…you were a human?” Frisk nodded, not being particularly secretive about that fact and Willy shifted uneasily. “So is it true you guys have, like, pussies? Holes that lubricate themselves?” Frisk nodded and tilted her head. Willy looked down, his pants tented from his erection. The human reckoned she really shouldn’t, she should be running before Undyne caught up. But then again, she had been waiting ever since she laid eyes on the armless stud.
Strutting across the bridge, Frisk leaned Willy down onto the bridge, grinding against his crotch as he moaned and she silenced his sounds with a kiss. She pulled down his pants and rubbed his cock with a hand, feeling nearly spiky bumps along the underside that reminded her of some of the more hardcore dildos she had at home. Frisk lifted up her skirt, flashing her pussy to the Monster Teen as she slowly slid down onto him, grunting and breathing heavily as she struggled to take his ribbed cock in comfortably. She held up a finger to silence Willy as she managed to slide the last few inches in and rested comfortably on the armless monster’s cock. She held her hands behind her head and began bouncing, letting her chest sway for the boy’s pleasure and slamming her thicc ass down onto his crotch with each riding bounce. Willy groaned and Frisk looked to see Undyne staring at her across the bridge as the two horny teens fucked cowgirl style. Frisk stared the monster right in the eye as she bounced harder, bringing Willy to orgasm as he cried out in pleasure and filled her pussy with cum, Frisk controlling her breathing as she stared down the monster guard. She got up and walked away, Undyne no moving nor Willy as he panted and looked at his soft dripping cock. “Yo…”
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Frisk ran through the remainder of Waterfall, tits and ass bouncing as she ignored the whistling appreciation of an old goomba looking monster. “Nice tits babe!” he yelled out as Frisk tried to put as much distance between her and Undyne as possible. The caves began to open, returning to the high vaulted cavernous ceiling that Snowdin had been as the humidity began to drop and temperature began to rise. Frisk turned the corner to see the path running through a rocky outcropping, and standing atop the mini mountain was Undyne. The monster began launching into her monologue.
“Seven. Seven human souls, and King ASGORE will become a god.
Six.
That's how many we have collected thus far. Understand? Through your seventh and final soul, this world will be transformed. First, however, as is customary for those who make it this far…
I shall tell you the tragic tale of our people. It all started, long ago…
…
No, you know what? SCREW IT! WHY SHOULD I TELL THAT STORY WHEN YOU'RE ABOUT TO GET FUCKED!?! NGAAAAAHHHHHHHHHHHHHHHHH! YOU! You're standing in the way of everybody's hopes and dreams! Alphys’s history books made me think humans were cool… ... with their giant boobs and lewd swordswomen. BUT YOU? You're just a common slut! Fucking that boy in front of me so you could run away from me again!”
With that, Undyne undid her helmet, revealing an eyepatched blue fishy face as she stared down at Frisk and summoned her dildo spear, a sharp blue shaft extending from her crotch. “Time to get FUCKED!”
Frisk began running, Undyne chasing after them with their shaft bouncing up and down as she summoned similar spears and threw them, burying themselves in rocks instead of Frisk’s ass as she sprinted for Hotland, as advertised in a bright neon sign. A spear managed to catch her, seven inches of blue shaft burying itself in her ass instantly and sending her moaning and collapsing onto the ground. Undyne got on her and began raping her ass, pounding into it with no love or lube as she tore her a new one, Frisk gritting her teeth as felt her insides and her soul getting fucked raw. Her phone ran and Undyne fished it out of her bag to hold it up to her ear, pausing her thrusting for a moment. “I’ll let you answer it.” Frisk answered it to hear the familiar voice of Papyrus. “AHH, HUMAN!!! I WAS THINKING, YOU AND ME SHOULD HANG OUT WITH UNDYNE AT HER HOUSE!!! THAT WAY WE CAN ALL GET TO KNOW EACH OTHER!!!” Frisk managed to shove Undyne off her and ran away, her ass screaming with each thrust as Undyne rose from the ground and continued the pursuit. Frisk sprinted past Sans who was selling corn dogs while napping in his station. Undyne paused for a moment to slam her fist down. “Wake up guardsman!” she yelled before sprinting again to make up the distance Frisk had gained. The humidity was gone and the temperature began to feel like a desert in summer as Undyne slowed down and began breathing heavily.
“Nyah…human! Will…catch…you…” Undyne collapsed in her armor, Frisk screeching to a halt at the entrance to Hotland, a stitch in her side and her ass still pounding with pain as she saw the monster suffering in her armor. Frisk looked around and saw a water cooler, grabbing a cup and pouring some cold hydration onto the fish monster’s face. With a grunt, Undyne got to her feet, swaying uneasily in the heat as she eyed the human. She scowled at her for a moment, before stomping off back to Waterfall to cool off. Frisk collapsed onto the ground, catching her breath as she felt the hot sulfuric air fill her lungs. She looked up to see an imposing steel gray lab standing in the volcanic landscape. She had left Waterfall. She was halfway out of the Underground, she had to keep pushing forward.