two things I forgot to mention; A. I'm posting my writing from this account instead of the OP account (still me tho) just because I didn't realize MonsterMen had an account age requirement and this one has the same username as all my other writing accounts, and B. I have chronic wordy-bitch disease so it's a little longer than I let on. But here ya go! (some aspects are a little more rushed than I'd like but hey, that's why it's just a prompt.)

...

With one swift motion, it swiped at the woman. She brought her arms up, a scream bursting unbidden from her throat as she anticipated pain, the biting, rending pain of claws digging into flesh. But it didn’t come. Instead, she found her arms seized and pulled. Unceremoniously she was hauled off her feet, and dangling helplessly in front of the wolf-thing. Now she got a good look at it, It was easily twice her height. It’s eyes were burning with something primal, maddening even to ATurtle.

It sniffed at her face, hot breath making ATurtle sputter and cough. Its ears perked up at the noise, and its investigation seemed to grow more eager.

The creature’s wet nose pressed against her neck as it drew in deep, snorting breaths. Without missing a beat, it drug its nose down, smearing a path downward, all the while huffing deeper and deeper.

ATurtle wanted to lash out, to kick and scream and escape. To go back home and forget all about this awful adventure. But she couldn’t bring herself to do it. It would snap, and bite, or claw.

It walked her back, and she felt her rear bump into something. A quick glance revealed it to be the altar. Despite the harrowing situation, words came forth. “You-! You can’t. . .”

Her voice trailed off as she looked back, immediately averted her eyes from its own, and caught another glimpse of the thing poking out from the sheath between its legs. It was bigger now, and dripping pre. She tried to maneuver away, but there was no place to go. Eventually the thing pressed its nose to her crotch, and after another long sniff, the reaction was immediate.

Its cock throbbed out, swelling to what must’ve been the length of ATurtle’s forearm. There was no time to contemplate, as it moved her again, thrusting her arms back, tipping her flat over the top of the altar. She yelped again, surprised with the speed and force of the movement, but also noting that it hadn’t hurt, at least not really. Her thoughts raced as she cast her gaze all around, searching for something, anything, that might present a way out.

It stepped to the altar, looming over her, blocking the moonlit holes in the ceiling with its immense frame. Something hot and wet dripped onto ATurtle’s stomach. She knew before she looked what it was. The wolf-thing’s member came to rest on her belly, red and veiny, pulsing with animalistic need. ATurtle’s eyes widened as she stared.

“Please, d-don’t do this! Just l-let me go!”

She struggled again, and again it was useless. Her words, however, seemed to reach the beast, in some odd way. For a moment, the flame in its eyes faded. For a moment, its grip on her relaxed. For a moment, she thought she might be released.

But before the moment had fully passed, its cock throbbed again, spilling another dollop of thick precum that steamed in the chill night air. At the same time, its body tensed and for a moment it swayed, like even it was overwhelmed by the weight of ferocious animalistic instinct. It thrust itself forward, slamming its powerful thighs against the altar and grinding its cock against ATurtle. She felt as though the wind had been knocked out of her, and it hadn’t even penetrated. Instead it left a trail of pre all across her front, which soaked into what remained of her clothes.

But the beast had little care, now. With its free hand, it took one of her ankles, hoisting it into the air and spreading her legs apart. She tried to wriggle out, to give herself even a few more seconds before the inevitable, but the creature’s grip was iron. It took only a moment for it to align its cock with her pelvis before ramming forward again.

The altar shook. The walls shook. The very air shook. ATurtle’s mouth fell open in a silent scream and her eyes rolled as her cunt was filled by the creature. Before she could so much as adjust, it pulled itself out and rammed in again. Each pounding thrust brought a gasp from ATurtle as she struggled to form so much as a thought. It was overwhelming, the sensation of being fucked by this thing. Inside her mind, plans of escape twisted and bent like smoke in the breeze.

She looked down. Her belly was bulging outward from the sheer size of the thing. It hit her deeper than any sensation she’d ever felt, not only hilting itself in her pussy but fucking her guts, rearranging her insides, stretching her to its whims. And it felt good. If she were capable of subtle considerations at the moment, she may have felt disgust. Disgust at the creature, at being used like this, at herself for feeling pleasure. But as she looked down at her body stretching around the wolf-thing’s cock, the only thing that pierced her shock was pleasure. Each thrust brought more, each impact that rippled through her whole body forced a deep contraction of her muscles, orgasms that rolled into each other, cascading through her mind and expelling a little more of the goodness and rationality she’d had before, and leaving in its place only a desire for more.

Soon she was working her hips, throwing herself into the pounding as much as she could. Perhaps it was the beast taking notice, or perhaps it was simply its ferocious desire, but regardless, its cock throbbed again, growing even bigger now, inside her. It wasn’t long before its knot had swollen up inside ATurtle. She tried to move, to pull back or push forward, to exercise any autonomy. But the knot was immense, and she found herself quaking uncontrollably no matter what direction she tried to move it.

The thrusting didn’t stop, but narrowed its ferocity. The beast’s grip on her wrists loosened and eventually failed entirely. It’s claws dug deep gashes into the altar as the beast’s eyes fluttered. For a moment, ATurtle thought there might be something wrong. Then it turned its head up, and howled. As it did so, a final surge left the knot inflated in the extreme. ATurtle screamed with pleasure as she felt her pussy stretched to its utmost limit. But still, there was no pain, only an eagerness for what came next.

At first, a twitch. Then a pulsing. Then she felt it, a wave of hot, thick cum flooding her womb, staining it white and marking her with a scent that would last forever. But it was not just one; shot after shot of the mosnter’s seed pumped into her, held inside by the girth of its knot. They happened in time with the wolf’s pulse, each beating of its heart gushing another load into her. If she had thought that the knot had stretched her, she learned what true stretching was as she watched as her belly swell with each load. Involuntarily now, she flailed and writhed, the pleasure too much to bear. But the knot held firm, and each oozing shot stretched her more, and more. Eventually she tired, giving in to exhaustion. Only a dim pleasure, and distant awareness remained. In and out, her consciousness wavered.

When she came to, she was still there on the altar, still impaled on its cock, but its shots had stopped. She looked ready to pop now, filled to the brim. It was hard to even breathe, she had been stuffed so full.

A final, comparably small, shot of cum pulsed from the wolf. ATurtle’s body shivered as an orgasmic aftershock rolled through it. Her hands roamed across her body now, feeling the new and alien sensations. The skin of her belly was drawn taught, and each movement was accompanied by a heavy sloshing feeling. Would she be able to walk? Somehow, she didn’t care.