(suggested by HyrulianHero500, AnAverageGuest and others. Enjoy!)
The following takes place after "Umbreon x Espeon".
Why do I keep getting myself roped into situations like this? Am I really as much of a sister-fucking degenerate as the fucking Lannisters? Why can't I resist the temptation of my sisters' sweet, warm, delicious pussy? ... Huh, guess I answered my own question.
He and Espeon had continued hooking up off and on in the months following their encounter in their Master's bedroom, matching the cycles of her heat and his general horniness. They had to be careful, of course, to prevent pregnancy and (as far as he knew) keep his siblings from knowing what they were doing. There were times when he thought he could stop, when he could pull himself away, not think with his balls, and try to rebuild a healthy relationship with his sister. But being a mindreader, every time he'd try to start that conversation, she'd give him that sultry look, raise her tail nice and high, and sway her hips so the light would catch the dewdrops of arousal on her soft, velvety cookie. And just like that, his will would break, and all he could think of was filling his sister with his cum.
Truly, he didn't know who was the bigger degenerate: Espeon, or himself.
But of course, with everyone living in the same household, it was nearly impossible for a secret like that to stay a secret. At some point, his sister Sylveon learned what was going on. Maybe she found their web history, too. Maybe she caught them in the midst of their hookups. Hell, maybe Espeon told her, in the hopes of starting up some incestuous harem for him. Whatever the reason, one morning he woke up to find his legs bound by Sylveon's tendrils, as his other sister had her face next to his crotch, licking and suckling on his morning wood like a popsicle. When he finished, she told him that she wanted to have just as much sex as Espeon was getting, and she wasn't afraid to take charge to get what she wanted. Umbreon lamented his lot in life, but still did his best to enjoy being used as a toy for his horny sisters.
Which brought him to now, a few weeks later, as he sat in his bed while Sylveon's tendrils gently and sensuously massaged his erection.
"My, my, my," She giggled, resting her head on a paw as she rubbed and squeezed him, "Is it just me, or have you gotten bigger, big brother?"
"Y-yeah, well," He explained, stammering at the delightful sensations, "Having tons of sex can make dicks and pussies grow. A-all that extra testosterone and estrogen, I think."
"Mmmhmm," Sylveon purred, not sounding entirely convinced. Still, she continued to stroke him, smirking naughtily as Umbreon grunted and whimpered in front of him. "Tell me, big bro, has Espeon ever used her psychic powers to jerk you off?"
"Oh yeah," He answered.
"And how does that compare to this? I might not be able to telepathically squeeze your prostate, but I like to think I can do things she can't."
"Like what?"
"Like this." His sister brought her muzzle down, her warm tongue licking at his large, sensitive balls. Umbreon moaned, the golden circles across his body lighting up with pleasure. Sylveon alternated between the two, massaging one with her paw, while licking and kissing and suckling on the other, all while her tendrils continued to massage his length.
"Oh, Arceus," He moaned, "What did I do to deserve this?"
"Be the best big brother ever," She answered, "To the best sisters ever. Now, hurry up and cum for me. I've been craving your seed all week." As if finding an extra gear, the Eeveelution moved faster, licking and stroking him faster and faster, her bright blue eyes lust-filled and focused. Umbreon felt his climax building quickly, and he leaned back into his bed as he relaxed and let go. Sensing his balls clench in her mouth, Sylveon positioned a tendril at Umbreon's tip. Thick strands of cream splattered against it, collecting it and dribbling it down the underside of his cock. The Fairy-type lapped at it greedily, finding salty-bitter seed just to her liking. Her tongue worked fast, but still droplets ended up across her face, on her ears, on her paws and forelegs. After five or six seconds, Umbreon started to come down, settling into a comfortable afterglow.
"Satisfied?" He asked, watching his sister lick his cum off her fur.
"Very," She replied, cleaning her tendrils with particular care, "I wish you'd share with me more."
"Share what?" A new voice asked.
Umbreon and Sylveon turned. Sticking her head through the ajar bedroom door was Eevee. Despite her appearance, she wasn't actually the youngest sibling, merely the only one that hadn't evolved. Still, most of the family treated her as a baby sister, spoiling her as everyone's favorite. She stepped into the room, eyeing them both with curiosity, not disgust.
"Were you two having sex?" She asked.
"No, we were-" Umbreon tried to explain.
"Yes, we were," Sylveon said, cutting him off as she licked her tendrils clean, "He just came, but you're welcome to join us."
"Acreus and Giratina, girl!" He protested, "You can't just offer me up like that!"
"Why not? Everyone already knows about your interests, and you're not the only one in need of a good fuck. Isn't that right, Eevee?"
Eevee shrugged. "We all know what you're into, Umbreon. It's not some big secret that you've been banging us one by one. If I'm gonna lose my V-Card, I'd rather lose it to someone who loves and cares for me rather than some random dickbag who just wants a hump-and-dump."
"Or doesn't know what they're doing," Slyveon added, "Virgin-on-virgin action is hardly ever mindblowing lovemaking romance shows make it out to be. Which is why we are going to help her with that little problem, aren't we, Umbrie'?"
Umbreon looked quickly between the two, groaning with exasperation. "Why does it feel like I'm becoming everyone's dildo?"
"Because your cock is that damned good," Sylveon giggled, "And you're an onii-chan who's not creepy or rapey. We're all grateful to have a brother just as kinky as we are."
The Fairy-type stepped away, letting Eevee hop up and climb onto Umbreon's chest. She leaned down and kissed his nose, and again on his lips. They both closed their eyes, and he wrapped his forelegs around her, pulling her closer and deeper. She was forceful and inexperienced, licking his chin and biting his whiskers, not really knowing how to step up from lip-to-lip. Umbrie, however, knew exactly what to do, and promptly took control of things. He slid his tongue into her and was rewarded with a delighted moan as Eevee melted under his touch. With practiced skill, his tongue wrestled hers into submission, exploring every part of her mouth. He could still taste the sweet tea and Skittles she had for a snack not long ago, which only made things even better. After a long moment, Eevee leaned back, gasping for air in aroused pants.
"You're such a good kisser!" She declared, and Umbreon could swear he saw little pink hearts dance in her eyes.
"You have me and your sister to thank for that," Sylveon giggled behind them, her paws spreading Umbrie's legs wide, "You're only as good as the partners you practice with. Now c'mon, help me get him ready for another round."
Eevee maneuvered over his body, flipping around until her fluffy tail and thick rear were in his face. It didn't take long to figure out their plans, as Umbreon felt two tongues brush against his sheath and limp cock. He gasped with pained delight, his still sensitive member being barraged by his sisters' lick attacks. It twitched and spasmed as it started coming to life, slowly becoming hard and erect again. When he was half-up again, Sylveon slid down, taking both of his furry black balls into her mouth. At the same time, Eevee took Umbrie's dick into her mouth, her tongue running circles around his tip.
"OOOhhhhh!" Umbreon moaned, his eyes rolling to the back of his head. Had he not just orgasmed two minutes ago, he might've busted right then and there. Any regret or concern he had about his incestuous relationships were tossed out the window under the tender mercies of his sisters. Arceus, how could something so wrong feel so right? He almost didn't notice Eevee pulling his dick back, scooting up his chest until her fluffy muff was inches from his nose.
"C'mon, big bro," Eevee teased, wiggling her tail and behind lustfully in front of his face, "You're not gonna leave me hanging, will you? You know how to satisfy a female, right?"
"He sure does," Sylveon said, massaging his balls with her tendrils, "He's got the most talented tongue in the whole house. Espeon raves about it. She even talks about it in her sleep."
Umbreon would've rolled his eyes at that elsewhere, but lust got the better of him, as he grabbed his sister's rear and lapped at the dew on her cookie. The sweet and spicy taste of arousal danced across his tongue, leaving him desperate for more. Eevee moaned against his cock, her vibrations adding an additional thrill to it all. His entire world was filled with thick brown hair, the scent of need, and feel of tongue and tendril against his sex.
"Giratina's ass," Sylveon swore, "I love the smell of these balls. Remember this scent, Eevee. Nothing sets the mood more than the smell of a heavy, sperm-filled sack just begging to be emptied. Now, do you wanna feel his tongue in your snatch, or do you want to go all the way today?" Eevee hesitated, her tongue stopped at Umbrie's tip.
"I'll stick with his tongue," She said hesitantly, "I heard cum takes forever to get out of your fur. Plus, it tastes all salty and bitter and yucky."
"It can," Sylveon said, scooting up Umbrie's body as Eevee leaned back onto his face, "His isn't so bad, though. But suit yourself, I get to have his cock all to myself." Umbrie felt his sister's cookie drag across his aching cock, and he moaned into Eevee's fluffy ass with growing anticipation. Eevee whined at his touch, and promptly silenced him as she planted her ass firmly on his face. He had just enough room to breathe through his nose, breathing in the stank of her feminine arousal, which only tickled that most primitive part of his brain. He took the whole of her vag into his mouth, his tongue snaking in and penetrating her most intimate space. Eevee yelped in pained delight, her entire body tensing up as she was touched in ways she'd never had before.
"Told you it was amazing," Sylvie giggled, her tendrils holding his member in place, "Now, let's begin." She brought herself down on Umbrie's pillar; after their many bouts together, the Sylveon was loose enough that there was only a moment's resistance before her folds slipped open, and he was inside her. They evolved Pokemon moaned together, Umbreon muffled under so much Eevee ass. Sylvie slid down his delicious cock, letting it fill and stretch her in all the ways she loved. She stopped just above his knot, taking a second to get used to his girth before moving up to start bouncing.
The three of them moved together like this, licking and thrusting and moaning, enjoying the sensations and the bonds between them. Eevee was over the moon, the feeling of her brother's tongue far better than her own, if only for his particular skill. Sylvie enjoyed having her brother's dick filling her, as well as watching the expressions on her sister's face. And Umbreon... all Umbrie could think about was his sister's tight pussies squeezing his cock and tongue, and satisfying everyone's burning lusts.
They went at it for over a minute, but nothing lasts forever.
"Ah! Guys!" Eevee cried, holding herself up on Sylvie's shoulders, "I, I think I-I'm about to-!"
"Don't hold back, baby!" Sylvie declared, "Just let it happen! Cum all over your brother's face! Let him be your first!"
That was enough to push her over the edge. Pressing and grinding her rear against Umbrie's muzzle, Eevee screamed, announcing her orgasm to the world. Her inner walls clenched around her brother's tongue, holding it in place. Hot poke-girlcum squirted into his mouth, and he moaned his approval as he drank it all in. Eevee held onto her sister, moaning into her sister's white fur as her backlegs gave out. Umbrie had to hold her up just so he could breathe.
"Oh yeah, that's it," Slyvie moaned, bouncing faster and faster, "C'mon! Just a little bit more! Just a, just a... holyfuckingshit!"
Sylvie's orgasm was just as intense as her sister's. Despite not taking the knot, feeling the swollen flesh rub against her clitoris was enough to push her over. Her entire body clenched and shook, her breath escaping in a shuddering whimper. She pressed herself down as hard as she could, desperate to feel her snatch get plugged and filled with her brother's potent, delicious seed.
Umbrie, having just came a few minutes ago, was the last to finish. But after feeling and hearing both of his sisters climax atop of him, he couldn't - wouldn't - hold back anymore. With a feral growl, he thrusted harder and faster, taking hold of Sylvie's waist. Her folds gave way, and he shoved his knot inside her. Feeling the warm tightness envelop his sensitive organ, it was more than enough to push him over the edge. He grunted, his cock throbbed, and he filled his sister's womb with his seed. The feeling of hot, sticky semen set Sylvie's already sensitive insides on fire, and the Sylveon moaned as she was struck with yet another orgasm. Eevee, still riding the high of her climax, saw all this, and pulled her sister in impulsively for a kiss. Slyvie had no time to be shocked, and kissed right back, their tongues dancing and wrestling in each other's mouths.
They licked and bucked and rode out their collective orgasms for the better part of a minute, fully in hog-heaven. As they came down, Eevee and Sylvie slid off Umbrie, laying on either side of their brother. He wrapped his arms around them, pulling them into a hug as his erection finally got soft and retreated for the last time. He kissed them both, letting them rest their heads against his chest.
"Thank you, big bro," Eevee sighed, "You were amazing."
"Told ya," Sylvie giggled, nuzzling him, "You have me to thank for that. Oh, Umbrie, remind me to talk to Espie about blocking your sperm tomorrow. Unless you want to clean up after yourself right now?" She asked the last part optimistically, shooting him big puppydog eyes.
"That's gonna be a hard pass," Umbrie said plainly, stroking her back, "I love you girls, but not enough to eat my own cum." Sylvie pouted, but still held him like a body pillow.
"Hey," Eevee asked, "Do you think we can talk to Espie tomorrow and make this a foursome? I wouldn't mind having some experience with girls, too."
"Arceus have mercy," Umbrie swore, smiling all the same. His sisters were downright insatiable...