What Are Siblings For?

Twilight nestled between Shining Armor's legs, pushing her nostrils against his balls and inhaling her brother's scent. She gave his sack a couple appreciative laps before she moved her attention higher. Her tongue drew up the length of Shining's cock, locking eyes with her brother when she reached the top and giving him a quick smile before taking it into her mouth. Twilight's tongue danced around the head of his cock, slurping up the precum that was dripping out. She popped the cock out of her mouth and began to slather her tongue up and down, coating the shaft with her saliva.

Once she felt that she had given his cock the spit-shine it deserved, she took one last lick from the base up before impaling her throat down on his member. She might have been a little out of practice when it came to servicing a stallion, but she had done this for Shining enough times that muscle memory let her take the whole length down her throat with minimal effort, only taking a couple bobs before her muzzle was touching his stomach. She continued to bob up and down his throat, dancing her tongue around his shaft as she blew him, and settling into a comfortable rhythm.

Wet slurping sounds filled the royal bedroom as Twilight did her thing, interspersed with the two siblings' moans. Twilight loved the taste of Shining's cock, having never found another stallion who could quite match the tangy musk flavor that his cock exuded. She traced her tongue over every vein and ridge, trying to taste every square centimeter of that delicious dick. She looked up at her brothers face to see his eyes shut and him biting his lip, obviously trying to hold back and make this blowjob last as long as possible. Shining's hips began to buck upward into her, driving the shaft farther down her throat as she sucked. She could feel it starting to throb harder, so she wasn't surprised when she felt his hooves suddenly push down on her head, driving himself as far into her as he could before spilling his seed into her stomach. After the first couple spurts she pulled off, allowing the last few shots of cum to land on her face and in her mane. She had always enjoyed being splattered with his seed, proudly carrying his scent on her as long as she could before being forced to wash it off.

"Wow Twi, I swear you get better at that every time I see you," Shining said, smiling down at his little sister's cum spattered visage.

"You know I always give my best to you, bbbff," Twilight responded, "but I do miss when we could do this every day. I can't say that I'm not a little jealous of Cadance being able to taste you all the time."

Shining tousled her mane lovingly, not minding the cum that smeared onto his hoof as he did. "You know I miss you too, but doesn't the time we spend apart just make these moments that much more special?"

"Absence makes the heart grow fonder, huh?" Twilight mused, "I'm familiar with the theory, but I don't think there's enough empirical evidence to make that claim certain. Maybe if we ran a few tests, like gathering a group of mares and stallions and having them rut at different intervals across a series of years? Then we could measure the pleasure and intensity exhibited and compare it across the curve".

"Twilight..." Shining started to say, rolling his eyes at his sister.

"Maybe we could even define an ideal period of time to go between sexual encounters in order to optimize the experience!"

"Twitwi, maybe we cou-"

"Of course, any good experiment needs a control group. A couple of ponies fucking everyday at set intervals to set a baseline..."Twilight looked at her brother with wanton eyes, "what do you say, Shiney? Want to help with a little science experiment?"

Shining Armor laughed. "Nice try sis, but I think both our schedules are a little full to manage that". He got off the bed and nuzzled against her, nibbling her ear before speaking softly into it, "why don't we just make the best of the time we have right now?"

"Can't blame a girl for trying," Twilight said with a huff. "Well then, I guess we better move on to the main event."

Twilight walked up to the bed and placed her forehooves atop it. She turned around and locked half-lidded eyes with her brother before slowly flagging her tail to the side, presenting her glistening pussy to him. "Well big bro, you aren't going to keep your favorite little sister waiting, are you?"

"You're my only little sister, Twi," Shining said as he mounted her. Twilight could see his hooves come down beside her head and felt the flare of his cock rub teasingly against her lower lips. "But no stallion would dare leave a lady waiting at such a kind invitation".

Twilight moaned as she felt him enter her. It was a tight fit, one of the benefits of alicorn physiology was that she never got stretched out for long before returning to normal. But between how damp she was and the spit lube she had provided her brother it wasn't too difficult for him to slide all the way into her. He gave a few shallow bucks in and out before at last he hilted inside of her, and she could feel that wonderful fullness that had eluded her for so long.

Shining bent over her, letting her support his well built body as he licked up a dab of his own cum form her forehead and then kissed her. The two siblings shared that jizz between them as they made out, comfortably connected with each other but neither moving just yet. After a few minutes making out like that, their mouths separated.

"How do you want it, Twiley?" Shining asked.

"Do me hard. I've been waiting for this for a while, and I need it rough. Do me like Cadence has you do her maids."

"Heh, alright sis, you asked for it. Just let me know if it gets too intense for you." Shining said.

Twilight felt Shining rear up, bracing his hooves against her flank. Suddenly, he withdrew nearly his full length out of her before he slammed back in with all the force a former royal guard captain could muster. Twilight cried out in shock at the force of being split open like that, but before she could even catch her breath he was doing it again and again to her, never even giving his sister a moment to catch her thoughts. Twilight could do little more than cry out and moan as her body was rocked back and forth by the force of the rutting.

"What's the matter sis, too rough for you?" Shining shouted as he continued to plow his little sisters cunt, "And you call yourself an alicorn? I've had servants on their first nights take it better than you." Shining smacked Twilight's cutie-mark with a hoof to get her attention back.

SMACK "Want me to stop," he yelled

"no" she murmured.

SMACK "What was that? I couldn't hear you." Shining put one hoof on her head, pinning it sideways to the pillow. "I asked if you want to stop wasting my time and let me find a mare worth fucking."

"No, please... don't stop," Twilight whimpered

SMACK "Then tell me what you want, slut," Shining said as he pistoned his cock in and out of her. He knew he wasn't going to be able to last long at this pace, but he was too into it to care.

"Fuck me" she said

SMACK "I can't hear you. Speak up!" He smacked her ass again.

"Fuck me harder, big bro! Fuck your little sister raw!" Twilight shouted.

Shining focused all his strength and attention on giving Twilight the best dicking of her life. The bed rocked underneath them, straining to support the force of Shining's bucking. Twilight gasped every time he drove into her, and let out a deep moan as he withdrew. After what felt like ages, Shining thrust into her one last time as deep as he could go, before coating the inside of her womb with his semen. Twilight shuddered as she felt wave after wave of her brother's essence spray inside of her, causing her to clamp around his cock and hold him inside as she reached her own climax.

Once they had both come down, Shining withdrew from Twilight and collapsed backwards onto the floor. He looked at his younger sister's rear as she still lay splayed open in front of him, his cum slowly dripping out of her well used cunt and dribbling down her legs.

"Wow Twi, that was great. What do you say we go grab a bite to eat and get some rest?" Shining asked.

"What do you mean by was, Shining? I hope you don't think we're done yet." Twilight turned around on the bed and looked down at her brother from her perch.

"But Twi, come on now, surely you could use a break. That was a pretty intense fucking just now." Shining replied, beginning to get slightly nervous.

"Would Cadence have been satisfied with that?" Twilight asked, a predatory grin beginning to spread across her face.

"Well, no... but Cadence has a whole staff and guard troop to tend to her needs when I'm not around." Shining responded, realizing that he hadn't taken his sister's alicorn libido into account when he showed up without Cadence today. Usually when they visited, the two of them kept each other entertained while he recuperated.

Suddenly he was being lifted into the air in his sister's familiar magenta aura.

"I told you I've been preparing for today, didn't I?" Twilight smirked.

Suddenly Shining felt a new spell brush over him and noticed that his little soldier was once again at full attention. He found himself being guided onto his back, his cock pointing ramrod straight toward the ceiling. Twilight was once again straddling him, wings fully flared and horn glowing bright. Shining noticed that Twilight hadn't released him from her hold yet, making him unable to move. He felt his cock pressing against her back door.

"Don't worry Shining, your little sister will keep you ready and able for your whole visit." She smiled as she lowered herself onto his dick, the walls of her ass parting to let in the intruding member. "For now, just lay back and let me take you for a ride".

As Shining watched his younger sister bounce up and down on his cock, still pinning him to the bed and conjuring something that he could feel teasing his own back entrance, he took a moment to appreciate how lucky he was to have two beautiful alicorns in love with him. As he shot another load into his sister's ass and felt her magic parting his cheeks, a shared sense of ravenous lust overcame them both, and that was the last coherent thought either pony would have until morning.