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Calling In A Favor

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“fucking a kk, yes i’m fucking ready, now put that thing in my right fucking now!”
It was rare enough that Dave allowed himself to have such a passionate response to anything, so Karkat knew he meant it. The troll carefully aligned the fist-sized head of his 15 inch cock with Dave’s nookslit. It was a ridiculous juxtaposition in Karkat’s opinons; it seemed impossible that his inhumanely sized dick would be able to fit inside Dave’s (what was the human word? Oh yeah) vag. But his blonde boyfriend had been desperately insistent, so Karkat began to push.
Dave moaned loudly, the precum-drooling cockhead pressing against his erect clit. With a sudden pop! the glans of Karkat’s massive shaft slid inside Dave. He let out a sound just barely on this edge of a scream, more like an intense yelp, but instantly caught himself and warned sharply, “Don’t you dare take it out, bitch.” He had anticipated Karkat’s gut response: pulling out and apologizing and refusing to penetrate him again.
“J-Just give me a second,” his human boyfriend gasped. Karkat kept stock-still, as Dave’s ragged breathing slowed, and the teenager moaned. Karkat experimentally pushed a bit more of his wrist-thick bonebulge into Dave, eliciting another sharp gasp, but no vocal protests.
Karkat had to admit, the feeling of the warm, tight tunnel over his cock was amazing. The instinctual part of him wanted to rut wildly, to take pleasure where he could get it, but he was far too concerned with Dave’s comfort to indulge that part of him. He leaned forward, locking lips with the supine boy, his lips melting into Karkat’s as they began to kiss passionately. Once more, Karkat inched his thick dick forward, causing Dave to moan into his mouth. He pulled back, just a centimeter, then pushed his massive prick in just a bit further.
Karkat let his fingers find Dave’s chest, dragging his sharp nails over Dave’s top surgery scars, and finding his pert nipples, tweaking them gently. The troll now had his dick about 5 inches deep in Dave, and as he withdrew for another thrust, he broke their kiss, both boys breathing heavily. Dave’s skin was flushed, and Karkat’s grey cheeks betrayed a hint of his red blood underneath as he once more pushed his dick forward into the lithe boy beneath him, burying it a full 7 inches.
The sudden increase in dickflesh plunging into his technically-virginal depths (Dave had practiced with a alchemized dildo only inches shorter than Karkat, but somehow it didn’t compare to the real thing) caused him to wince. But the pain melted into pleasure, and a deep sense of eroticism from being filled with the biggest cock in existence in their new universe.
“keep going, man. im fine.” The blonde insisted. Karkat was unsure, as his face was scrunched up in discomfort even as he said it, but the troll’s dick was very sure, and it insisted he keep going as well.
Karkat fell into a slow rhythm, pumping only a few inches at a time in and out of his boyfriend’s cunt. Slowly, Dave’s tense muscles relaxed as the fat shaft inside him began to feel more and more natural. Soon he was panting in pleasure as Karkat took 6 inch strokes in and out, plunging in a full 9 inches at the deepest.
“Yes. More, dude. Fill me up,” Dave’s voice was more plaintive than Karkat had ever heard it. He allowed himself to insert an extra inch or so into the small human. “More!!” The boy insisted, and Karkat obliged forcing in ever more of his gigantic dick.
The troll was now fucking Dave in earnest, taking long footlong strokes, all but the final bit of his shaft entering Dave.
Then, something inexplicable happened. A green glow enveloped the two boys groins, crackling energy palpably arcing across Karkat’s skin. Then he started to grow.
Dave’s moans went into an intense crescendo. Karkat’s massive dick was expanding deeper into his boyfriend, the base visibly widening. “YES!! YES~!! MoooooRE!!” Dave’s voice was desperate and full of lust. The bulge of Karkat’s expanding dick was beginning to appear in Dave’s midsection, a mere shadow at first, but within seconds, a fat bulge of his huge bellend, distending the flesh of Dave’s belly each time he plunged his 3 inch wide cock deeper into Dave.
Karkat had no clue what was happening; on some level he feared for his boyfriends safety, but the moans and groans and expressions of pure pleasure coming out of his mouth kept him from doing anything but fucking the blonde boy harder as his shaft expanded inside of him. The once-huge, now-massive cock must have been 20 inches long, a bulge stretching from Dave’s belly button up to just below his sternum clearly visible.
“WHAT THE HELL’S GOING O-” Karkat’s frantic question was cut off by Dave grabbing the back of his head, and forcing their lips together for another kiss. Karkat’s inner beast took control, jackhammering Dave into the bed, his cock extending past 2 feet long, poking out of Dave’s belly almost grotesquely. Each time he pulled back, Dave’s stomach went back to being a flat, smooth surface, but each time Karkat bottomed out, the skin of the human’s belly stretched like a circus tent, the central pole a foot long and thicker than Karkat’s bicep.
And it wouldn’t stop growing! Each additional inch made the sensation exponentially more amazing for the troll, but it didn’t seem possible that Dave could accommodate such a monster. But yet he did; no matter how long Karkat’s cock grew, Dave’s body responded like rubber, stretching whatever way Karkat shoved his cock into the boy.
Karkat’s shameglobes, too, were not left out of the equation. As he continued rutting Dave, his balls swelled and expanded, now the size of human basketballs, forcing his legs wide apart and swinging ponderously with every thrust. He could feel them tightening; he knew that he wouldn’t be able to hold out much longer, the feeling of the tightening canal around his expanding shaft was just too much.
“I-I THINK I’M GONNA CUM!” He managed to pant. Dave groaned louder, the 3-foot dick stretching his body to the point that he should have felt nothing but pain, but instead felt deep, complete pleasure. “Fill me up dude!! Give me your cum!!!!”
It was too much for him. Karkat’s balls drew up in their massively oversized sack, and his cock, still buried deeply inside his boyfriend, shot cum at such velocity that the stream stretched out Dave’s belly even more. The volume of the jizz was incredible, unbelievable. Dave’s belly began to fill up, expanding with the cum that Karkat was unloading into him in gallons. The dick was so thick that almost no jism could escape, only a tiny fraction of the load jetting out at high pressure onto Karkat’s thighs as he kept slamming his pulsing cock into Dave.
Dave’s belly was beginning to resemble a sphere, bulging out so thickly with Karkat’s load that the grey-skinned alien could almost no longer see his face. And still, Karkat kept cumming, his beach-ball sized balls still massively swollen with jizz. Even with Dave’s body so bulging with cum, every time Karkat bottomed out, the last 6 inches of his 3&½ foot dick stretched out Dave’s belly.
The sensation was too much too keep going, so Karkat, with a heavy grunt, buried his megacock deep inside his boyfriend’s cunt, the head perfectly outlined through Dave’s flesh, still pumping out the last bits of his load. Finally, the cock gave its last few pulses, and Dave’s body ceased its swelling, the soft flesh of his belly now a sphere roughly 4 feet in diameter, mostly cum, partially cock filling it.
The two boys panted heavily, neither moving, both basking in the afterglow of the most intense erotic experience of their relatively short lives thus far. Karkat collapsed on top of Dave’s swollen belly, the extra pressure causing more of his own cum to spurt out around his softening dick, spilling in a huge puddle on the carpet.
“WHAT-” Karkat was still breathing heavily, “THE HELL WAS THAT?”
Dave laughed, “you mean other than fucking amazing?” He didn’t give Karkat time to respond, “it was Jade. i called in a favor.”
“A super pervy favor, if you ask me.” Jade’s voice cut across the room from where she stood, leaning casually against the doorframe. “Honestly I’m disgusted I had to even witness this.” Her voice betrayed her own amusement though.
Karkat grunted, standing up and walking backwards, his mostly-soft, hose-like cock unreeling from Dave’s slit, cum flooding out and expanding the insane pool of jizz on the floor. “WELL THAT’S JUST DANDY. MIND TURNING MY BONEBULGE BACK INTO SOMETHING NOT RIDICULOUS???”
The end of the huge grey cock flopped out, landing on the soaked carpet with a thwack. Now unhindered, semen poured from Dave’s cunt, his belly slowly deflating. “Dont you dare, Jade. remember our deal.”
The witch shrugged, “He wanted y’all to stay like this for 24 hours.” She turned, walking out the door and waving over her shoulder, “Have fun, you two.”
Dave sat up, grinning at his alien SO. The short troll was steaming, “FUCK YOU STRIDER, YOU KNOW THAT?”
Dave laughed, almost uncontrollably, “yeah, that was the whole idea, after all. now get back over here, with nuts like that you gotta be ready for round 2 by now.”