Deep in the forest, far away from society, a Servine sits silently, staring at two spotted eggs. They had a very subtle sheen of fluid, like a thin layer of film that’s there to protect the egg. It would be believable, especially to someone like Finn the Servine. He had evolved a little earlier, and was still supposed to be snivy age at 15, but according to his mom, getting to the evolution stage early is something to be proud of. You’re taller, stronger, and are seen as more mature (than you probably are).
Finn likes to think he’s mature, but something about the things he thinks about makes him think there’s something wrong with him. His eyes carefully watch the eggs sitting in the nest. As he does, his cock slit parts open, two stiff shafts growing harder and harder, until they’re at full mast. A full foot-and-a-half long, throbbing and drooling with precum.
Finn grunts a little bit, his arms trying to push his cocks back into himself. A blush covers his nose. It’s embarrassing, very embarrassing, but the erection speaks for itself. Last night, as he was about to tell his mom he was heading to bed, he walked right into his large serperior mother grinding her pussy over the eggs, thrusting them inside of her, moans high pitched and orgasmic. She, of course, had her own thick cocks out, squirting precum all over the nest, covering it with her scent as she fucked herself, pushing the eggs deep inside her pussy, then pushing them right back out.
Finn couldn’t look away. He could have sworn his mother heard him gasp, but either she didn’t hear him or she didn’t care. Seeing his mom so depraved was…strange. It turned something on in the back of his mind that he didn’t feel was there before, and it quickly came apparent when his cocks became harder than ever before. He scurried out of that bedroom, to his own little nook, and quickly tried to relieve himself, possibly thinking about anything but his mom…but it was no use. His heart fluttered, his soft vines quickening around his cocks, and the moment his mind thought up the idea that his vines were his mothers, he came harder than ever before. 
And so, here he was the next morning. It was early, and his mom should be still asleep. The sheen of the eggs isn’t a protective film, it’s his own mother’s pussy fluids, maybe even her cum. The Servine whimpered, before starting to stroke his cocks in front of the eggs. Inside them are his new siblings that his mother laid for him. He knew that a Pokemon lays eggs when a man and a woman have sex, but he doesn’t have a dad, at least not one he knows about. The mystery of how the eggs came to be was a mystery indeed, but the fantasy of his mother just becoming spontaneously pregnant was also a fetish Finn didn’t think he had, but did. Womb filling with eggs without warning, pussy squirting, motherhood flourishing through their body…!!
And without Finn preparing properly, he came all over the eggs, splattering them with his gushing, musky seed. He let out a whimper, quickly about to run and get a cloth to clean them up, but as soon as he turned around…
“Hi there honey~”
Finn screamed. His mother sat at the entranceway to the nursery. It was clear she had been there for a while, comfortably coiled up onto herself and leaning most of her weight on the side of the entrance. 
“M-Mom!!” Finn huffed, “It’s- I mean- You- I wasn’t-”
“It’s okay honey~ It’s okay~” She giggled, slithering into the nursery, “Tell me hon, you didn’t think I didn’t see you last night~ Did you~?”
Finn gulped, his eyes frozen in fear, staring at his mom. After a few seconds, he quickly shakes his head.
“Mhmhm~ It’s okay dear, mommy’s here~” His mom moved up to Finn, gently coiling around him, “You’re a growing boy, and growing boys can have some strange desires, right~?”
Finn could feel his mother’s gentle grip on the base of his still-erect cocks, “That’s no reason to hide them from me~ I’ll show you how good it feels to let go~”
“Mmhhnh~” Finn moaned, his eyes fluttering closed. Part of him wanted to wiggle free and run, but his mother’s vines around his cocks felt so, sooo good~ He thrusted against his will as he clenched his teeth together. The vines speed up slowly, wrapped around both his cocks indevidually and squeezing them rhythmically. Clearly, she’s had practice with this.
“Mmmnh~ You’ve grown so much since you were just a Snivy~” His mom purred, “No wonder, really~”
“N-nnh~ No…wonder…?”
His mom flashed her beautiful amber eyes, “I hate to keep secrets from you, but there’s something I’ve been…doing for quite a while, ever since you came out of your egg~” She snickers, trailing a vine up to his chest “When I laid eyes on your cute little body and smooth belly, gosh I was in love~” She says, gliding her vine down his front, “But when I got to your little cock slit, and saw you sporting longer than average behemoths like these? Why how couldn’t I help myself~?”
“W-wwhhuhh~??” Finn gasped but was quickly silenced.
“Oh I’m not done yet honey~” His mom grinned, getting closer to his face, “It was practically every night I would sneak riiight up into your room and slip those beautiful cocks deep inside my womb~ Feeling your cute little cub seed fill me was everything I could ever need~! Especially after being without a man for so long, and you were the most handsome Pokemon I knew~”
His mom licked his lips, “Ohh~ But eventually one night, I become pregnant, and birth these cuties~”
Finn huffed, “W-wait- I’m- I’m a daddy…?”
“Yes you are hun~ And I’m your lovely mate~” His mom giggles, “How does that make you feel~?”
Finn’s heart rate skyrocketed. So many fetishes he didn’t know he had came rushing through him, cum gushing through his cocks right up to the tip, until…!
“Ah-ah-ahhhh~ Not yet honey~”
Suddenly, two vines push into his cock tip, blocking his cum, “Your little sisters are about to hatch~ We wanna save as much cum for them as we can~”
Finn’s legs wriggled in his mom's coiling as the eggs in front of him begin to crack. The shell falls inwards, and the little snout of two baby Snivys appear from inside the eggs. Their eyes are closed, not used to the light yet, laying on their back.
“Look at that~” Mom whispers, “Your sisters, and your children~ Ohh how alien this is~”
“M-Mommy…~” Finn moans, his orgasm having been completely stopped, “Y-You-”
The vines pop out of Finn’s surprisingly stretchy cocks, a splattering of precum shoots from both rods.
“You’re…allowing me to…f-fuck my baby sisters~?”
“I’m not just allowing you, honey~” Mom says, hugging him close, “I’m encouraging you~ I want more kids, and these wombs aren’t going to fill themselves~”
Picking the baby Snivys up gently, Finn’s mom slides them under Finn’s engorged cocks. As if trained already by the corrupt aura flooding the room, the baby Snivys suddenly grip each cock with their hand, nuzzling and letting out cute little sounds.
“Now~ iiin you go~!”
And with one thrust, Finn’s mom pushes each of the little Snivys over both of Finn’s cocks. Their bodies easily stretch over his cocks, squeezing them perfectly like little baby toys. They let out squeaks, their eyes barely open yet, but Finn could feel their pussies quivering, already sending orgasmic sensations through the recently-hatched cubs. It was as if they were built for sex…no, it was like Pokemon were built for sex. It was as if his memories were gently being shifted. This was right, fucking his own baby sisters. It was for building the family~! Each generation would be better and more built for sex, and that’s exactly what he’s meant to do!
“M-Mommyy~~!!”
Finn moans loudly, his head craning up, before suddenly meeting his mommy into a deep, passionate kiss. Tongues twist together, and saliva is crossed as Finn cums harder than any Pokemon ever could. Gallons of seed gush into the quickly-impregnated Snivys, turning them into cum socks. His mom keeps them on his cock for a solid ten minutes, the orgasm lasting the full length. It was mind-numbing and perfect.
Once the orgasm gently began to settle down, his mother slid his Snivy siblings off his throbbing shafts, precum still rocketing out of his cocks at full speed.
“You did perfect, honey~” His mom congratulated, “My perfect little child~”
But Finn, somehow, was still horny. His breath was hot, and his heart was in his throat, panting with sexually corrupt eyes. It was as if his mom knew this, and before long, he could feel two even thicker cocks slip right between his legs, right over his sensitive pussy. 
Wait…did he even have a pussy? What was going on…?
For a moment, Finn’s mind did a heel turn. Something was going on. No, he did have a father. He wasn’t the best, but he could have been certain that that was who gave his mom those two eggs, not him! Something wasn’t right! What-
But before his mind could figure out anything more, his pussy was penetrated. His mom filled his whole body with her warm corruption. Finn let out a brilliant, feminine moan, kicking his legs with glee, his cocks throbbing right in front of his face. He panted, pushing himself deeper on the cocks, wanting them entirely inside his womb! He wanted his own eggs, and to be his own mommy, and to fuck his kids, and then watch his kids fuck their kids, and then-
His mother cummed hard, inflating his tiny body with her corrupt cum, impregnating him possibly fifty times over. The 15-year-old’s moan was high enough to notify everyone in the forest how he was being fucked and cummed in by his own mommy~ 
“Mmmnh~ Good boy~” His mom huffed, “Wanna go again~?”
But unfortunately to the Serperior, the Servine had completely passed out, his eyes had become swirling spirals while he had a big, goofy smile plastered on his face. His mother let out a sigh, half out of admiring how cute he was, and another out of slight disappointment for him not lasting longer. It was okay. If Finn was to get used to this new life, he’ll have to practice, and he had done pretty well for his first time~
The Serperior let the Servine lay with his sisters, all three covered in a layer of their own cum and all bellies filled with eggs. Feeling satisfied with herself, while not entirely satisfied with her sexual desires, she slithers out of the nursery and into the living space. She moves into a new room, where a large, male Serperior is bound by thick, purple tendrils, his mouth and eyes covered. The Serperior then effortlessly morphs into a Snivy, snapping her fingers and making the tendrils blocking his face move away. The Serperior gasps.
“Haah…!!” He shouts, looking down at the Snivy, “Y-You! W-What have you done to my mate??”
“Oh stop complaining. I told you I was borrowing her form for a little while…while I get to have fun. I thought I told you that the last time we talked?”
“F-ffuck you!” The Serperior shouts, “D-Don’t touch my son!!”
“Oh I touched him plenty~ You should have seen it~” She snickers, levitating up to his body where his cocks are. They suddenly throb, “Ohh…but you wanted to see it didn’t you~? Pedophile~ This is what you wished for, wasn’t it~? For a tight, little girl’s pussy to sliiiide onto your cocks~?”
As the Snivy says this, she touches the bound Serperiors cocks to her tight pussy. The Serperior bites down, trying to resist, but his cocks say it all. The Snivy snickers, her eyes glistening a dark purple, 
“That’s it, you creep~ Don’t worry, I’ve done everything you wanted. I’ve turned your son into a cute little herm, filled his womb and his mind full of family love, and even made him fuck his own baby sisters, just like your pedo mind wanted~” The corrupt Snivy giggled, “But…wait, what’s that I hear~? You want more don’t you~? Cum, then, fill my pussy~”
The Serperior’s cocks were barely inside her tight Snivy pussy, the tip only touching the floating Pokemon’s entrance, but he still came. He couldn’t help it, it was exactly what he wanted.
“That’s a good little boy. Maybe next time I’ll turn you into a Snivy and fuck your little underage pussy. You want that~?”
The Serperior, who had done all of this, wished none of this could have happened. That he could control his desires and not have made such a deprived wish to the heavens one orgasmic night.
…but the strange creature who had taken his mate’s body was right. He did want this. With a heavy blush and drool coming down from his mouth, he nodded, and he nodded eagerly~