A kick in her belly woke Toph Bei Fong.
The gravid young woman grunted as she felt the creatures within tumble and toss. She moved her hands slowly along her swollen marble of a tummy. Her skin was stretched taut around her packed womb; it was thin and sensitive, whispering against the slightest touch. Even the mildest movement from the offspring within could cause a kick or bump to be visible on its surface. She was so heavily swollen that she couldn't even so much as stand without help from others or her bending; her navel poked out of her tummy and was well beyond reach of her arms, which could only stretch halfway along her belly's circumference.
But then, that was to be expected. Even before being born, sky bison commanded formidable sizes indeed.
Though her children were yet unborn, Toph could still 'see' them in a fashion. The earthbender summoned her powers to view the world through echoes and tremors and turned it inwards. She 'saw' her offspring inside her womb, a quartet of still-growing sky bison calves that were connected to her. She pulsed umbilical lifeblood into them, a duty which left her tired and weary even before the sheer size of her offspring was considered. Her body had changed enormously to help incubate another species; her breasts—relatively modest at the best of times—were aching and swollen, well over twice their usual size. Toph had put on some maternal chub in the usual places: around her neck and cheeks, in her upper torso, and especially around her hips and thighs. Ever since coming of age into her twenties and developing into a sexually mature young woman, Toph had been told she was something of a 'shortstack'—whatever that meant—and she presumed that this would only add to her appeal.
Well, maybe she would play nice with other humans when she got back to civilization. If she felt like it. For now, though, there was only one beau for her.
And from the way the air parted overhead, she couldn't help but smile. Here he came now.
Appa touched down alongside his old friend, the girl who was now the mother of his children, and approached her tenderly. Toph's heart felt warm; despite his size, he was quite protective and gentle. Appa sniffed her a few times and Toph laughed with delight at the warm breeze of his breath against her skin.
"I've been fine," she said, her voice low. One of her offspring kicked and she gasped as her stomach pushed out momentarily. "Correction," she declared. "We've been fine."
Appa snorted happily and licked one long, warm stripe along the crest of Toph's belly. The warm embrace of his touch made her shiver, and the calves squirmed inside her. Appa pushed some berries and herbs he'd gathered towards his mate.
"Thanks, boy," Toph said as she picked one up. As immobile as she was, she relied on him to bring her sustenance. She gulped down a berry and then angled her milk-swollen tit to her own mouth, washing it down. As her mouth worked, she couldn't help but reflect on what brought her here…
---
"I don't think Appa holds a grudge against you." Aang was sitting across from his friend Toph. From the way the air moved, she suspected he was idly playing by spinning a ball in the air, though she couldn't 'see' it as it didn't touch the ground.
"I know, twinkletoes." Toph crossed her legs as she bared her feelings. "But when I let Appa get kidnapped in the desert…"
"That wasn't your fault," Aang pressed. "You couldn't protect him and us. You did your best."
"I know," Toph repeated. "But I still feel bad. I'd like to make amends, if I can…"
There was a clatter as Aang stopped playing with the ball. It fell to the table with a pitter-patter that Toph felt as much as heard. "Well, why not?" he said. "I'm sure Appa would love to spend a few months with you on a… a…"
"Life-changing field trip?" Toph supplied.
Aang just laughed. "Yeah, I guess that's one way to describe it. Take as much time as you two need—just bring him back in one piece."
Toph grinned. "Can do."
---
The wind kissed her skin as Appa carried her through the air. They'd been flying for a few days now. Given Toph's inability to see, she couldn't steer him; but that was fine by her. This was a trip for Appa. Let him take her as far as he wanted.
"How you doing, big guy?" Toph asked, patting him on the crown of his head. The sky bison rumbled pleasingly in response, a quake that Toph felt in her whole body. She grinned and gave him a scratch. "Thought you'd like it."
Hopping off the saddle, she allowed herself to sink into his fur. She drank deep in his scent, reflecting on how overpowering his musk was. Though sky bison were affiliated with the air nomads, he was still a beast; a certain earthiness was to be expected. In this, Toph felt a kinship to him. Some might find such smells to be overbearing or unpleasant, but she liked their scent. They reminded her of the wilds that she found so much more appealing than she did cities.
"I'm real sorry, Appa," Toph murmured. She rubbed her hands through his fur, noticing from the small shivers that danced back through her fingertips that the great bison enjoyed her touch. "I know it was years ago… and that it wasn't my fault. But." She sniffled. "I bet you suffered so much while you were away. I… I'm really…"
Appa rolled his shoulders affectionately and rumbled something inarticulate. Toph got the sense that he was returning the sentiment—that he was letting her know that he forgave her. Tears dropped from her cheeks to speckle against his fur.
"Thanks," she whispered.
After a long day's travel, Appa touched down on a remote island. Toph happily hopped off, appreciating how she could see through the ground again. Appa trundled alongside her and she followed, wondering where he was going off to. His journeying seemed deliberate.
As they went through the island, Toph became aware that that stones around her were actually long-crumbled ruins; air nomad style, if she had to guess. Was this some long-forgotten refuge of Aang's people?
In the center of the ruins was a vast coliseum-like structure with a domed roof to protect it from the elements. It was so large that multiple sky bison could've fit inside—and as Toph was able to sense what seemed like great stone troughs for feeding and watering, she thought that was by design.
"This was for you!" she exclaimed. "For the bison. And if you came here on your own, it's probably related to something innate. A breeding cycle, maybe?"
Appa couldn't respond, of course, but she could hear him trundling around, sniffing sadly at the walls and stonework. She suspected she was right; this was a sky bison breeding ground. But poor Appa didn't know that he was all alone. The fire nation had done their job too well; the bison were exterminated.
"Sorry, boy," Toph said, feeling for him. He bellowed mournfully, perhaps understanding.
---
Toph left Appa to spend time in the breeding ground; it seemed too personal for her to butt in. Instead, she wandered the island, finding old mosaics and pottery. She couldn't make rhyme or reason of them, but perhaps Aang would find meaning in them.
As night fell, Toph gathered some food and took refuge in a small grove not too far from the ruins. All alone with her thoughts and her body, Toph did what many sexually mature adults would do when alone and bored—
She, for lack of a better term, began attending herself.
"Nngh," Toph grunted, her breath coming hot between her lips. She plunged two fingers into her snatch while using her thumb to attend to her clit. "Ghhh…"
She could feel the arousal spreading through her body like a flower unfolding its petals. It started down in her womanhood and quickly filled the rest of her, pulsing in her fingertips and her cheeks and the tips of her breasts. Her whole body felt hot with arousal. "Nngh…"
So focused was she on her own business that she didn't internalize the approaching rumblings until they were almost upon her. She recognized them for what they were immediately: Appa was investigating.
The sky bison poked his head into the clearing, sniffing once, and Toph felt embarrassed. Her moans had likely drawn his attention; did he think she was hurt?
"I'm f-fine, boy," Toph said as he pushed into the clearing proper. Her whole body was still hot with arousal and the scent of her pussy filled the air. "Nothing to worry about…"
But Toph's measure of the situation changed when Appa dipped his head close to her. His breath was hot against her pussy and he opened his mouth, his great broad tongue lolling.
"Wh-what are you—AAAAHHH!" Toph's voice peaked as Appa pushed his tongue up against her sex. He was far, far too broad to actually stick it in her, but the warmth and pressure was something else entirely. He licked a long swipe up her sex, the push doing far more for Toph's body than her own fingers did. When he took his tongue off she was left sprawled and panting, but mere seconds later he licked her again, his tongue slapping lewdly against her most intimate parts.
"What's… happening, what're… you doing…" Amidst the haze of sheer erotic pleasure, Toph was confused. Appa was an animal, a bison, he shouldn't be interested in her like this, he shouldn't be considering her a mate, and she certainly shouldn't like it…
But fuck, she did like it. His tongue pushed against her yet again, mashing her plump lips against her body, and she moaned pathetically. Arousal had turned her legs into jelly and she was completely at Appa's mercy—and she loved every second of it. This was beautiful.
And it seemed Appa wasn't just content with his tongue. A new smell joined that of Toph's arousal; a heavy, pungent, erotic musk. Through the earth, Toph got a vague sense of Appa's body—and she realized that something was unfurling between his legs. His cock was unsheathing. And she had no doubt he intended to use it.
"I want you to," Toph whispered, realizing it only as she said it. Partly because, well, she was already worked up and her body craved a good fuck. But more than that. Why was she on this trip? To make amends—and Appa, poor Appa, was alone in his species' breeding grounds, never to find a mate again. Except he'd claimed one here. And how better to make amends than to give him the pleasure he so desperately craved?
The sky bison lifted his head from Toph's sex and repositioned himself. In a sense, he 'mounted' her, though he put no pressure on her directly, instead hovering his upper body in the air. His great, broad cock—as big around as a human's wrist and as long as their forearm—rubbed against Toph's swollen, sopping lips. Moaning, she worked her hips back and forth, delighting in the way that his shaft glided along her slick pussy.
"Please," she whispered, and as if he understood her assent, Appa made his move.
With a low rumbling grunt, the bison angled his hips and thrust in. Immediately Toph's whole being changed.
"AAAAAGGGHHHHHH!" she howled, her body parting desperately around her partner's shaft. Holy fuck it was big, it was big, she could barely endure it; her pussy ached and she squeezed desperately around him, rewarded by a sharp sensation that rocked through her. If she thought her limbs were jelly before, now they were really useless; her body was limp and quivering as it was plundered by a beast far bigger than it.
But despite the sheer stretch, the ache of having something that big inside of her, there was pleasure. Oh there was pleasure! The ache quickly subsumed into a low thudding drumbeat of sheer delight that started low but quickly picked up. Tears speckling the corner of her eyes, Toph mewled as she squeezed tight and clenched around Appa's cock. Her bestial lover growled and hiked his hips back before thrusting in again, even harder.
He surged in even deeper and Toph's body bucked around it. She tried to say something in praise or encouragement but all that emerged was a tired, desperate wheeze. Moving one trembling hand to her torso, she alit it on her stomach and realized with a certain giddiness that she could feel Appa's cock distending her body. Now this was lovemaking.
Appa bucked in again, harder still, and Toph flirted with unconsciousness as his broad, flared tip kissed up against her cervix. The sensation of having her deepest sanctuary knocked against made her whole body tense as tight as a whip, a tension that only furthered the tide of pleasure surging through her.
Somehow she found the power to speak. "Th-that's… hnnnm, as f-far as you'll go, buddy…"
Appa seemed to understand. Holding firm for a few seconds, he exhaled sharply—and then he picked up his tempo.
The great beast slipped out of Toph and then immediately back in. She gulped in air as her body bucked from the pressure. Appa grunted and slammed in again—and again—each push faster than the last, each hilting as much of him in her as he could. Her poor cervix was being pulverized by his cock.
Toph mewled inarticulately as she rode it out. By now her whole body was a wildfire of pleasure that couldn't be stopped. Sexual blissed danced everywhere, spurred onwards by Appa's ceaseless plowings. The wet sound of bison cock plundering Toph's pussy—whlap, whlap, whlap—resounded in the quiet glade, accompanied by the sky bison's bestial grunts and Toph's high, blissful whimperings.
Toph's body lurched as she came; she sobbed with joy as orgasm rocketed through her, exploding like fireworks. She could feel it knocking through her like an earthquake. Her pussy danced and squeezed tight around Appa, and her bestial lover grunted from pleasure and slammed in even harder. Toph nearly passed out as his cock smashed against her cervix, sending sensation racing through her even as her body shook with orgasm. She could hear his voice growing intermittent; his cock was starting to throb in her.
And then he came.
With a rough, bestial bellow, Appa threw his head back as his cock pulsed thick jets of cum direct into Toph's womb. The earthbender whimpered as she was flooded full of more cum than any human could hope to match; thick jets of sticky, aromatic seed began pulsing inside of her. Her belly stretched, rounding out like a balloon as her body strained to contain it all. Of course, a vessel can only hold so much—eventually cum started gooshing out of her to stain the meadow underneath.
With a satisfied chuff, Appa yanked out of her, the abrupt departure making Toph hiccup, and more cum started leaking out. He cuddled close, nuzzling and licking at his new mate, and Toph, who was too weak to move, pushed a trembling hand up against his snout. "There, there…" she said, even those words a chore to say. Her body was so thoroughly used that she was moments from passing out. "I got you… I…"
She fell into blissful slumber.
Toph woke the next morning around dawn, her body weak and aching and reeling with aftershocks of pleasure in that way that only comes from a night of thoroughly excellent sex. She tried to rise and gasped as her torso sloshed with cum; she was still packed tight with Appa's gift. Tentatively, with trembling fingers, she reached down and nearly yanked them back in fright when her fingers alit on a stomach that was much further out than she was used to.
"…oh," Toph said eloquently.
She managed to rise, her legs shaky and her stomach reeling with cum, and as she did so, she heard Appa raise his head behind her. "Don't mind me," Toph said, waddling inelegantly off. "Just gonna—hrrk—w-wash myself clean…"
There was a natural hotspring a half-mile away or so where the air nomads seemed to have built a bath. Toph slipped in with a shudder and began washing herself clean. She'd expected Appa's cum to leak out of her as she walked, but only a little had. The rest had stayed inside. As she reposed in the warm water, Toph poked experimentally at it. This was unexpected, but she thought she could get used to it. She bet she'd look cute with a paunchy belly full of cum.
After bathing, she meandered around the ruins, picking up herbs and roots for an early lunch. Around the time when she was finished, Appa found her—and she could smell that he was ready for another go.
Well, it only made sense. Bison, like most beasts, underwent a breeding season. He wouldn't be satisfied with just one session.
As she processed this revelation, Toph immediately came to a decision. "Sure," she said, leaning gently back and spreading her legs. Her body quaked with anticipation. "I'm here for you. Whatever it takes to make amends."
With a delighted snort, Appa approached, his cock unsheathing, and had his fun yet again.
The two of them stayed on the remote island for several weeks, lounging and exploring and eating and bathing and fucking. Oh, there was so much fucking. At least once a day, though Appa was rarely satisfied with just one go. Toph eagerly let him in. She was pleased to make up for her failure to him in the desert all those years ago, and besides…
It was, frankly, the best sex of her life.
But only a week or two after they started was Toph woken by a new sensation, one she'd never before encountered. The earthbender felt a tiny little stir, as well as a set of small, even-tempoed thumpings. Curiouser still, they were coming from inside her, but felt distinct from her own body. She rubbed her stomach in confusion. It was almost like she was…
And realization hit like a thunderclap. Like she was pregnant.
"Oh," she said dumbly, still rubbing her stomach. She recognized the mysterious thumps as what they were, now: tiny little heartbeats. Four in total. "Oh."
Her voice woke Appa, who happily nudged her with his nose and then gently licked her tummy. Toph realized that he'd known she was pregnant before she did; likely he'd picked up a change in her pheromones.
It made a perverse sort of sense. Throughout the ruins Toph had found what seemed to be childcare and childrearing facilities for bison calves. But they were far too small to accommodate a fully pregnant female sky bison.
But for pregnant human women? Yes, they were sized just right.
"The air nomads mated with you," Toph stated in realization. "You're compatible with humans." She had no idea how it was possible, but the evidence was undeniable. "And you… you…"
She continued rubbing her stomach in awe and wonder. "You bred me, Appa. I'm going to have your babies."
He rumbled happily and licked her tummy, and she could only reflect that it was a good damn thing that Aang gave her months for this trip.
They stayed on the island and it didn't take long for Toph to swell up. By the following week her paunch was enough to ride up her shirt. By the week after, she had to waddle as she walked. Within a month, she looked nine-months pregnant.
And she kept on growing.
Bison calves were large; a single calf would grow its mother large enough to put a woman overdue with triplets to shame. And Toph was pregnant with four of them. It quickly became apparent that she couldn't fully care for herself, but that's what Appa was there for. The white-furred beast eagerly nuzzled at her stomach and licked her as she grew, and made sure to bring her lots of food. He even learned to manipulate an earthen jug left over by the nomads to keep her watered as well. Toph burned with appreciation even as she was left so heavily pregnant that she could no longer move on her own. It was a beautiful relationship, and she was beyond happy for it…
---
As she dozed after a particularly filling meal, Toph replayed the past few months over and over again in her mind—but then she was woken by a sharp tug down in her stomach.
"Wh-whuh?" she said, rubbing her hands along her stomach in concern, only to wince as it happened again, sharper this time—and then she felt liquid pooling on the ground between her legs. Her water had broken; it was time.
Well then.
Leaning back, the gravid earthbender took in regular breaths. Contractions started pulsing in her body and she felt one of her calves push down low into her birthing canal. Grunting, she felt herself stretch far—much farther than even Appa had stretched her.
"Okay," she whispered to herself. "You got this. You—nnn—NNNGGHHHH!"
Words failed her as her body rocked with the sensation of birth. Tears stinging the corner of her eyes, she breathed in time to the contraction and squeezed the calf out. It inched with agonizing slowness through her body and her mind reeled. Before long she was going on autopilot…
And after nearly an hour of terrible exertion, the first calf was free. It was a messy, fluid-covered, probably ugly little thing—nothing was cute immediately after being born. But at it mewled and crawled, Toph carried it up to her breast and downright melted with joy as it began to drink from her.
"Hey there," she said. "Think I'll call you Twinkletoes."
But her body lurched again as another calf settled in. She had much more to go. Behind her Appa bellowed in commiseration, and she smiled.
"Don't worry, boy," she said. "I'm gonna bring all your babies, just wait and see."
And though it took tremendous effort, she did just that.
As the warmth of late afternoon baked against Toph's skin, she dozed off and on as her body recuperated. The bison calves alternately nursed from her, cuddled against her, or wandered off to play with each other or their father.
As she fell into much-needed sleep, Toph felt no small sense of pride. "How's that for making amends?" she murmured before she went to sleep. "You're not alone, Appa. The bison will return."
And with that, she slipped into deserved restfulness, a smile on her face.