Undyne drove the car back to her apartment in silence, careful to let the human in the back sleep. Her ass was still slick with his fluids, though pleasantly so; she shifted in place as she placed the car into drive.
She withdrew the human from the backseat, carrying him bridal style with only one arm. Once she made it into the apartment she laid him on the sofa, and checked the time.

2:32 A.M.

“What a night.” She mused. “And you gave me the munchies, punk.”

She slid out of her uniform, leaving only a tank top and hip-hugging panties to cling to her skin. It was carefully tossed into a messy pile which she pushed aside.

Andrew mumbled something and rolled over, and she clicked her tongue.
“You’re lucky tomorrow’s my day off.”

With that, she crouched at the bottom of the sofa, and carefully slid his pants off of his form. She followed with his shirt, which she tossed into the same pile. The muscular fish woman placed her hands over his bare feet once she was satisfied, and gave them a slight pull. Content that he was sleeping deeply enough not to wake up from her efforts, Undyne opened her mouth, and pressed his toes into her gullet. Her tongue danced over them, and he flexed unconsciously in his sleep. She reminded herself that she wasn’t doing this to savor him. She swallowed, and her throat opened to take his toes. The flesh constricted around them, and she sucked in a breath to swallow again. When her throat opened again she was able to slurp him in to his calves. She gave a little moan at his flavor, just salty enough to be discernible, just tender enough for that junk-food mouthfeel… why hadn’t she tried this sooner?

She shrugged. Drowsiness was beginning to take its toll on her, too. Going a bit more quickly, her hands seized his waist and pushed it further towards her. His toes found their way into her stomach as she crept further over him, teeth scraping against his rapidly thickening thighs.

Undyne swore internally as he began to squirm, before letting out a soft gasp. His legs shifted, and she expected him to try and jerk himself out. If he did, it’d be hell on her teeth.

He rose his upper body to look at her and adjusted his feet within her gut, making her instinctively open wider so that she could take his thighs in with much less discomfort.

“Susie does this all the time.” He mumbled, apparently still half asleep.

With a sense of pride at her achievement, she broke out into a grin that made her open even wider. She gasped- Andrew was shuffling towards her, sliding further into her gullet! Instinctively, she tried to close her mouth, and her lips tightened around his wide hips. She went to cough, used to a much more rough struggle, but the human stifled the blast of air. With a surprise unusual for the cocky officer, she sucked inwards- which only sent the human into a faster descent. Her tongue lapped over his chest, well toned but pathetic compared to her bulk, trying to savor the flavor that was rapidly flowing down her throat.

Her midnight snack wriggled the whole way down, grumbling about his sleep being interrupted with such a lewd dream, but his voice carried a hint of humor. She placed her hands on his shoulders and held them in place as she licked and slurped over him. His taste covered her tongue as he kicked and squirmed with her. He was up to his pectorals, which she eagerly gobbled and tasted, the stimulation making him kick and moan against her. When Undyne was contented with his cute moaning, she swallowed again, his shoulders vanishing between her lips. One only his head remained, Andrew lurched forward and bit her lip, ever so slightly. She snickered around him, and flicked him in the forehead before shutting his mouth and swallowing, sending all of him down into her gut.

Patting her gut, she scratched her ass and sat down on the sofa where the human had been sleeping, slouching against the armrest. She closed her eyes and within seconds was out cold, hand laid over her gut tenderly as the human settled and drifted back to sleep within her warm gut.

Undyne woke up, having sprawled all over the sofa in her sleep, to the sound of her phone ringing. Her gut was still massively stuffed, and every step made it quake and ripple. She searched for it, before fishing around in her work pants for her phone.

“Officer Undyne speaking.” She started, hand resting on her gut. “Oh, you mean my deputy? Haven’t seen him this morning, guess it’s another truancy for him. A couple more and he’ll end up in the county jail. I’ll warn him the next time I see him, don’t worry.”

She hung up the phone, and grabbed her gut, shaking it.

“Wake up, punk! Don’t make me extend your stay in my county jail!”

Andrew pressed his hand against one of the walls in affirmation. He was still tired, the damp warmth a lure for sleep. She patted him through her skin, and began some morning stretches that rolled and contorted the human in a variety of ways.

“Good morning. Usually the county jail takes the repeat offenders. They don’t usually leave.”

She moved into a pose that squeezed her ass cheeks together, a motion she repeated for the jiggle. With a content little laugh, she finished her stretches.

“Anyways, I think you need punishment for skipping class. I’ll keep an eye on you today. You’re lucky it’s my day off.”

He groaned within her, and she smacked her gut. “Don’t whine, punk.”

With that, she hefted her gut up and waddled to the shower.

When she was satisfied with the temperature, she stepped in and let the slightly warm water roll off of her. Undyne simply drank in the feeling, the change in temperature noticed by her passenger. He tried to say something to her, but the wall of muscle between them as well as the roaring of the shower made it unintelligible.

Within her, Andrew adjusted and tried to go back to sleep. When the movement stopped, Undyne smacked a soap-covered hand over her gut.

“Don’t fall asleep, I want you to serve your time.” She boomed from above him.

“Besides, you know you love it. I’ll put you to work soon.”

The human curled up but tried to keep himself awake. Undyne simply massaged the soap into her gut, then her ass, and sinfully, a few slippery fingers dove into her cunt. She rubbed, stomach clenching around its occupant as she routinely rubbed one out, juices rolling down the drain as if it had never happened. After what seemed like half an hour, the water began to grow colder and she turned it off.

Undyne dried herself off and gave her stomach a poke. The squirming within served as an affirmation.

“Sorry, you make showering so relaxing.” She said, picking at her teeth with a nail.

She opened a cabinet, devious smile on her face.

“I know you’re half-monster, punk, even if you don’t look like it.” She withdrew a box and began opening the contents.

“I felt your cum, how much you blow. Such a good protein snack.” She cracked her knuckles. “I’m sending down some digestible condoms. Fill them up, I want some snacks. Unless you want food pouring down on you?”

Out of everything that entailed spending time in a girl’s gut, nothing was worse than the smell or feel of food joining him. Susie loved to stuff herself silly while he was inside of her, leaving him to deal with the stench. He always needed three showers to get that feeling off of his skin.

He heard a gulp, and little rubber circles began to pelt him. He snatched each one.
“I’ll give you space, hold on.”

Still nude, Undyne walked back into her living room and started up a game. Something a cute lizard had sent her way. She sprawled out on the sofa, on her back, with her arms raised above her head as she button-mashed.

Within her, Andrew was finally able to take full breaths, albeit musky ones. Carefully, he gave his cock a few strokes, and it was rock hard. So much for hiding his affection. He grabbed a circle- a similar shade to the walls around him, were he able to see, and rolled it down his cock. He began to stroke, monster-stomach acid dripping around him. They weren’t strong enough to digest him, but they made for good lube. He began to stroke, up and down in a monotonous motion, leaning his head back and biting his lips. He began to think about how pathetic he was, within the gut of a superior woman. How she could digest him into nothing without a second thought, just because she wanted to.

That was enough. He arched his back and the condom began to balloon. Once it began to sag, he pulled it off and tied it, sitting it next to him. He grabbed another one. His balls began to gurgle as they went into full production mode, joining the cacophony of noises all around him. He closed his eyes and thought of Susie, her lips enveloping his view, or when she would hold him down and ride him.

He was losing his edge. Another cum-balloon joined her stomach to be digested later. He softened for a brief moment.

“Fuck!” He heard from above, and heard Undyne throwing something. She had tossed the controller at a wall, and switched the TV to some action movie. She smacked her gut, and he stirred, rolling another down his soaked cock.

“Punk, you still working in there? Better be, or you’ll be on my hips before you know it-”

He arched his back and let out an effeminate moan. The load was too much. The rubber rolled off and splattered into her gut. It was gone in seconds, absorbed by the walls and converted into energy. He grabbed another one, hoping she wouldn’t notice.

“Oh, so you like being treated like the gutslut you are? Is that why you’re such a miscreant? You want to be my fat…?” She whispered at him, poking her gut. She began poking lower at him, until she was rubbing at his cock through the muscle.

“...Or… do you want to be my waste ?” She teased, and pressed down on her gut. That did it- number four to-be-digested.” With shaky hands, he tied it off and laid it next to him. One more she wanted filled, but he was panting and his nuts were beginning to ache. He grit his teeth and rolled it.

“That did it, you punk? Might as well just fall asleep and let my gut do its work. Would serve you right.”

She laid back and said nothing more to Andrew, as he focused blindly on milking his cock for all it was worth. He thought of Noelle and her fat ass, Susie and all of her taunts, but there just wasn’t much left in the tank. A few beads, sure, but not a balloon like she wanted. He softened, letting out a frustrated sigh. He poked at his gut.

Silence.

He squirmed a little bit more, and his host squirmed, laying a hand on her gut. It squeezed ever so slightly, and he relaxed. Undyne rolled over, onto her stomach, onto him.

Her stomach groaned and gurgled as the condom slipped off, and he began to press against the walls and squirm, trying to get her awake, convinced she was picking on him. He jammed his finger into the wall and ground it, clearly intending to cause pain, but she only let out a belch in response. The walls constricted all around him, even his cock, accidentally milking out one last load. Exhaustion set in and he closed his eyes and drifted into a sweltering sleep as his home grew more and more damp.

Undyne snapped awake, hands clasping to her stomach. Just a toned 8-pack, no indication of an occupant. There was a bit more fat that lined her hips as well as poked in between the muscles.

She swore.

“Damn it, okay, you’re fine. Just an extended stay in the county jail.” She rubbed over her stomach, and it rumbled at her. “I’ll fix it, but be patient. I’m gonna enjoy you while I’ve got you.”

She rolled off of the sofa and eyed herself. He had definitely contributed a little bit of fat to her hips, but it looked like most of him had been converted to muscle. Her deltoids were thicker, as were her biceps. She flexed.

“Well, looks like you weren’t junk food. Talk about a protein bar.” She laughed a bit, rubbing her stomach.

“Didn’t mean to fall asleep there.” She whispered, a flash of guilt striking her. “I’ll make sure they don’t blame it on truancy.”

Within her, Andrew snapped awake to her frustrated yells. He was still in darkness, his prison surrounding him in a cozy warmth, but he was pinned in place and unable to move. When she went to flex, he felt his arm tense with hers. And as she stepped, it was as if his legs were walking. He could feel each and every one of her motions. He tried opening his eyes, and light flooded back into his vision. He looked at the mirror. Above him were a pair of tits that obscured the top of his view. He didn’t have a head to move, but his vision was centered right in her bright blue chest. The human went to open his mouth. Her belly button flexed perhaps a millimeter at his hardest efforts. He stared dumbly. This was his form now. He was still able to think, but why did he need to? He was bulk for the time being, and that meant being warm and cozy within her.

Undyne reclined back on the sofa and patted her stomach. She withdrew her cell phone.

“Hey, it’s me. Checked on our truant friend- he’s fine, seems like he’s caught whatever bug is going around. Wasn’t being truant, he just forgot to call the school. I’ll make sure he’s doing alright and he gets to class when he’s feeling better. Appreciate it.”

She hung up the phone.

“Ah, well. Least I can have dinner now. Protein rich, just like you.”

The pair walked into the kitchen, and Andrew drifted into a near-sleep state, resting but along for the ride. He wasn’t sure how long it would last, but there were worse fates to be had.

He wondered if he could taste through her taste buds… and if she’d decide to take another truant as a protein snack...