DETERMINED Interloper
For the moment, the final chapter for Simon and his actions in the Dreemurr household.
Oh, wait... you thought this was an UNDERTALE story? Heh, surprise, surprise, it's a DELTARUNE story! So, ah, spoilers for the Undertale sequel.
Again, the Undertale series exists in a place of Multiverses, and in this particular timeline, all characters depicted are 18.
Deltarune, Undertale, and all those parts were made by Toby Fox.
Simon cowered, feeling the strong, fleshy grip of the human around his little body. Those dark, sleepy eyes staring almost passively at the glowing rodent, looking through him, and yet taking in every detail of the tiny monster in the human's hand.
His little heart pounded hard in his chest as his glowing stripes dimmed in his terror, trying to hide, despite nowhere to run to. The curious digits of the human ran up and down along the monster as they studied him, turning him around and about. Simon felt some relief that Kris wasn’t about to harm him, not that he heard this human having hurt anyone, but, he knows many humans have hunted his kind for ages.
Simon’s glowing form went dark blue in his nervousness and fear, trying to convince himself that he wasn’t about to be harmed, but convincing his brain, well, that wasn’t being co-operative. The mouse’s eyes drifted along Kris' green and yellow shirt, seeing a pair of small breasts pressed on the inside of the fabric. The glowing lines went red as Simon blushed hotly, trying not to stare too intently at the human’s naughty bits.
Out of the corner of Simon’s eyes, he could see the human’s lip curl into a smile. The shirt being lifted up, showing Kris' bare legs heading up to Kris' underwear. The monster mouse squeaked, seeing a bulge along the forward cup of the briefs on the human. Were all humans made like this?
Simon’s heart was pounding rapidly, not sure what was going to happen, but Kris' hand that was lifting his shirt moved to the waistband, pulling it forward. The grip on Simon loosened. Gravity was all that held him as he flailed his limbs, reaching to get a foothold on the open air, but none came before he landed in the opened undergarment.
Landing upon soft flesh lessened the blow, but Simon was still feeling awfully disoriented before the elastic waistband was let go, snapping the underwear shut, dragging up the human’s penis and like a wrecking ball, collided with his chest, making Simon squeak quietly. Squirming around, Simon’s limbs pressed up against Kris' penis, the soft thing started to twitch, getting warm and firm against Simon’s hands.
There was less and less room in the briefs as Simon had awakened the beast within them. He gasped softly, trying to climb upwards, succeeding in only pulling back the foreskin of that shaft and revealing the human’s sensitive crown. As Simon touched over the spongy flesh of the tip, he could smell and feel the human’s slick preseed weeping out of that eye, covering his hands and face as it kept drooling out.
Simon’s body squirmed some more, the slick fluid causing him to slip, dropping down and down along that shaft, his rump hitting the base of Kris' member. Sighing quietly, Simon realized that heading up was getting him absolutely nowhere. Sliding left, Simon slowly went over the plump, smooth coinpurse of the human. If he was going to get out of here, perhaps down was the best way to go.
The smooth balls wobbled softly as Simon moved around. Kris' legs squirmed slightly, feeling tickled by the mouse’s activities as Simon slipped up underneath that sack. His whiskers brought him snout first to the human’s tight eager netherlips. This species was certainly amazing. He slowly rubbed around them, feeling them getting wetter and wetter against his fur. He shuddered softly, flicking his tail around in the underwear some more, growing more and more curious.
Simon’s glowing body provided plenty of light, the red hue of his blushing arousal shining onto a pearl nestled on the top part of that slit. Those monster fingers giving it a touch, feeling it just as hard and eager as the cock he just left, and responding to his touch so readily. If he was going to be stuck here, Simon figured it was his right to have a little fun.
The whole world within the underwear continued to shift and squirm. Kris was certainly responding to each of Simon’s touches before the underwear was pulled open again. Simon peeked out from underneath Kris' coinsack, giving a shy squeak up and out of the cotton prison. But, what he saw wasn’t just Kris, but Asriel staring down at the mouse hidden away down there.
Kris moved over, kissing their brother on the lips, stroking along his ears and up to his little horn nubs. Asriel couldn’t help but let out a happy little bleat, caressing along Kris’ less-than handful sized breasts, listening to his sibling groan gently under the attention.
Asriel’s fingers reached into Kris’ underwear, touching over his sibling’s cock before sliding lower, pinning Simon firmly against the human’s sack. Simon felt pinned up against the heavy, firm scrotum, breathing deeply.
Kris laid back, adjusting themself in the bed as Asriel moved up, pulling his hand up and out of the underwear, bringing Simon back up, now laid across the urethral bulge of the human cock. The siblings clung onto each other, kissing wetly and deeply. Kris’ legs spread apart, wrapping around Asriel’s hips, keeping him close.
Simon was between a cock and a hard place. The siblings were grinding against each other, rubbing their cocks, and him, through their underwear. Kris’ preseed leaked out of their member, soaking all over Simon’s hands. He felt a wetness above his head growing more and more. Glancing up, he figured Asriel’s cock was leaking from his underwear and soaking Kris’ with that heavy, goat-y preseed.
The mouse breathed a sigh of relief, feeling the siblings start to disengage, feeling that things were going to calm down for a moment. His respite was short lived, however, squeaking and clutching on Kris’ member as suddenly the whole world came into view. Breathing deeply, Simon gasped as he was then sandwiched against Kris’s shaft and the pink spire of Asriel.
Kris grinned in the kiss, licking deep into their brother’s mouth, dancing tongues together as Asriel responded with quiet whines and groans of pleasure. Kris groped their brother’s rump, bringing a bleat from Asriel as he felt a finger poke into his back door.
Simon certainly wanted to go home, but he was finding his opportunities to get there getting fewer and farther between. The siblings touched and rubbed each other more and more. Kris’ hand wrapped around both of those cocks and Simon, rolling the three together as they stroked faster and faster, making Simon squeak indignantly as his face was pressed up against the human’s covered crown, gasping as it was uncovered, then that soft, supple flesh wrapped up around his face a little, making him lose some air in that cockflesh.
That preseed filled up the pouch on the tip of that cock, nearly drowning the mouse as his glowing body squirmed more and more against the naughty cock. Simon squirming, putting his hands and feet on either side of Kris’ tip before extracting his head with a pop, tumbling head over tail onto the human’s tummy.
Dizzy and disorientated, he didn’t even acknowledge Asriel picking him up by the tail before he was brought to his sibling’s mouth like a bunch of grapes. Kris chuckled softly, lifting their head up gently, taking Simon into that warm, wet maw. The tongue of the human, thick, wet, and powerful pressed up against the monster mouse like an enormous, fat tentacle. Simon’s own member was rock hard, pressed up against the meaty appendage, shuddering deeply.
An instinct drove Simon, gripping hard on Kris’ tongue, starting to move his hips back and forth greedily, leaking his preseed all over that tongue, letting the human taste him. He saw the lips around him curl up in a grin. Asriel’s fingers kept a good grip on that tail, keeping him from dropping into Kris’ gullet, a good thing as human’s bodies were far more dangerous and scary than a monster’s.
Simon was reaching his orgasm, clutching onto the tongue tightly, grinding his cock back and forth, making love with the fat appendage as eagerly as he could, panting in the humid mouth. He felt a welling within his fecund sack, getting ready to bust his essence all over that tongue. His body tensing up, squeezing his eyes shut, finding it harder to breathe.
Just before he could release himself, Asriel’s grip on Simon’s tail yanked him out of Kris’ mouth. Simon squeaked in painful discomfort as his climax was snatched out of his grip. Asriel passed the indignant mouse to Kris who held onto the spit-soaked monster gently, making sure not to dab off any of that fluid.
Simon crossed his arms, huffing as his colour went to a deep red in frustration, glowing brightly before he saw Asriel getting onto his hands and knees. The mouse’s colour went a confused purple before he saw the royal prince’s bum presenting. It took him a moment too long to process what was going on before he could potentially stop it.
Kris held onto Asriel’s ass, spreading one cheek away with his palm. The hand gripping Simon raised its middle finger, making the mouse’s pointed muzzle stare directly at the pink pucker before him. Simon’s poor heart was pounding hard, squirming heavily in Kris’ grip. There was nowhere else to go, but Asriel moaned deeply, feeling that tapered nose push up against his posterior.
Kris was applying slow, even pressure with the little monster. They were grinning wide, seeing their brother’s body start to accept Simon inside, making Asriel squirm and groan in pleasure. Kris’ length throbbed hard beneath them, leaking more and more pre on the bed as they moved their hand from Asriel’s rump to his tail, holding onto it like a little saddlehorn, feeling it twitch in the prince’s sexual bliss.
Simon couldn’t move. He’s been in tight situations plenty of times, but this was getting ridiculous. Asriel’s walls clutched on him, keeping him from doing much more than squirm as Simon felt around the velvety walls of the prince. His glowing fur letting him see just a little of the pink walls surrounding him as he pushed against the walls, trying to make himself some room. It took awhile before he could find something to push again, a firm thing through the walls that Simon placed both paws on and gave a shove to have his back press against the wall behind him.
Asriel’s eyes rolled up towards the top of his skull as he bleated loudly, feeling the tiny hands rubbing over his prostate. The prince breathing hard, squirming his hips in the air before looking back at his sibling. Kris stroked their cock a moment more, pulling the foreskin back before climbing onto the back of their brother. That cockhead rubbing all around the prince’s buttocks before tickling over Simon’s hindfeet and tail as they stuck out of Asriel’s pucker.
Simon gasped softly, wiggling a bit as he felt his little feet getting touched all over. Not being able to see what was happening made him jerk and squirm some more. Laughter erupted in Asriel’s rectum as Simon felt Kris’ cock tickle all over his feet some more. The mouse’s hands balled up into fists, pounding on the fleshy wall before him.
Asriel kept yelping and groaning, feelin the thumping inside of his body, instinctively squeezing tightly all around Simon, groaning as his prostate gets worked on within his body. He was well on the edge of climax before Kris pressed their cock against Simon’s toes, then pushed in firmly, popping themself and Simon deep within Asriel.
That pace started slow, measured, even, pushing in and out of Asriel with the lust and the love a sibling could bring to their brother. Their breasts slowly brushed along Asriel’s back fur, stimulating them more and more before smooth sack slapped a furry one. Kris held onto their brother tightly, grunting lustfully as they worked more and more inside the prince and heir.
Asriel could only bleat in bliss, squirming all around, feeling Kris rubbing up against his prostate, and their little friend bouncing about inside of his body. Simon was bumped about in the monster’s rump, getting nudged and prodded by the human’s shaft again and again, rubbing him all over the walls. Simon felt his still hard erection press up against Kris’ before the human groaned loudly, splashing Simon with the torrent of seed welling up within them.
A glow peeked through the soaked mouse as volley upon volley of seed streaked all over his fur and body, making him squirm and moan. Simon panted hard, feeling out of breath as he clutched upon Kris’ cock, both himself and the human dribbling their seed over each other. Simon’s little glowing heart symbol pulsed with his fatigue, and he could feel a pumping through Kris’ body, blushing as that seemed to be the result of a heart, a real heart.
Pulling out, Kris collapsed their rump on their ankles, still breathing hard. Simon blushed hotly, seeing the puddle of seed Asriel unloaded on the bed despite having cum so often that night. The mouse let out a wide yawn, completely tucked out at this point, not caring what will happen to him at this point. The gentle hands of the human slowly picked up Simon, bringing him to Kris’ face. The sleepy-eyed human kissing his cheek before bringing him back down.
Simon blushed, seeing he was brought back between Kris’ legs. The mouse slowly stumbling into the human’s vaginal channel, curling up in his new home. He will come up with the DETERMINATION to leave his little mousehole again, but for now, it was a warm, loving home.