Yet again, Bahamut found himself with his own cock down his throat.

Ever since his 'encouraged' liaison with the red dragon Allera, his sister Tiamat had decided she quite liked the sight of him sucking on that fat shaft of his, and watching his stomach swell and bloat outwards as he stuffed himself with wave after wave of his own draconic seed.

Bahamut's lips came away from his shaft with a wet gasp, breathing heavily as his multi-headed sister wrapped herself around him, gently stroking the sloshing belly that stretched out in front of the rest of his body.

"Ahh, so big and full you are, brother. Doesn't it feel nice?" Her blue dragon head coiled around, flicking out its tongue to lick at the broken dragon god's taut middle. "To be so very full?~"

Bahamut didn't respond, continuing to pant as his breathing started to slow. Tiamat smiled, continuing to squish and stroke his full stomach, eliciting the occasional grunt or moan from her bloated brother.

"Hmmm...~" Tiamat muses. After a ponderous moment, she stands up and pushes her brother down onto his back with a grunt and a slosh. "Let's find out, shall we?~"

Tiamat's red dragon head snaked down, and after a playful lick, wrapped its lips around Bahamut's still throbbing shaft. Her other four heads' tongues teasing his shaft and balls. Bahamut let out a hoarse gasp as Tiamat leans down further, her throat bulging around his thick cock.

"Don't keep me waiting now...~" One of her other heads said before gently sucking one of his heavy balls.

Soon, Bahamut's entire body tensed, and a rush of cum blasted into his sister's throat, which visibly bulged with every shot. Tiamat let out a long, throaty moan as her middle bulged outwards with the mass of seed, one claw rising to stroke the soft, swelling mass.

Tiamat released her brother's shaft with a slurp, her vision blurring for a moment before her eyes snapping to focus, her gaze fixed on the slowly-softening shaft in front of her. "Again."

At Tiamat's command, runes on the heavy collar around Bahamut's neck flared to life. Magic shot through his body as his shaft sprang back to erect, his balls swelling and filling with new seed. Tiamat's black dragon head leaned down and engulfed the shuddering dragon's revitalized member, immediately taking the entire thing down its throat.

Soon Bahamut gave another spasm, again sending a tide of seed into his sister's stomach, further swelling the dragon goddess' fat middle. She let out a soft coo as she continued to swell, stomach gurgling with its load.

Again, Bahamut's collar flared to life, and again one of Tiamat's heads took his overused shaft into its throat, soon taking another flood into her bloated middle. Twice more she did this, Bahamut now limp from exertion, each of his tidal orgasms causing his sister's gut to swell further and further.

Releasing her brother's shaft, Tiamat stroked her engorged middle, slightly crosseyed. She looked ready to lay an entire clutch of eggs, such was the sheer mass of cum her brother had pumped into her stomach.

Panting heavily, the taste of her brother filling all of her mouths, Tiamat still hungrily eyed her brother.

"More..."

The collar again flared to life, once more refilling Bahamut's heavy balls, but Tiamat glared at the artifact around her brother's neck. "I said MORE!"

The collar went from merely glowing to practically shining, one of the runes sputtering out and going dark. Bahamut's eyes snapped open as magic roiled through his effeminate frame and concentrating in his balls, which began to swell even further. Already heavily enlarged by his initial transformation, they continued to grow even larger, heavy and overloaded with seed.

Almost drooling, Tiamat turned around and brought her ass down on her brother's hips, hilting herself on Bahamut's overworked, throbbing shaft. The dragon-queen's eyes roll back as she feels herself stretching around him, moaning as he penetrates deep into her heavy body.

"Fuh-Fill me brother..." She gasps out. "Fill your beloved sister like she knows you've always wanted to!~"

Bahamut lets out a final lusty moan as he practically explodes inside his swollen sister, her stomach visibly surging outwards as the tidal wave of cum in his overenhanced balls surges into her body. All conscious thought has left the dragon queen's mind as her bloated stomach continues to stretch out further and further in front of her.

Prodigious as they are, Bahamut's balls eventually expend themselves, the overworked dragon going limp and passing out. Tiamat holds her position for a moment before falling backwards with a heavy slosh, coming to rest next to her exhausted brother. She coos softly as she clutches her massively swollen middle, slowly drifting off to sleep.

~~~~~~
Bahamut opens his eyes. Next to him, his inordinately bloated sister remains asleep, breathing slowly. He gently nudges her, but she doesn't stir, or respond at all.

Cautiously, he gets to his feet, staggering momentarily from the combined weight of his own still-bloated stomach and his heavy, now even larger balls. Steadying his legs, he takes another look at his slumbering, swollen sister, and quietly as he is able, makes for the door.