He can't do the impossible

Declan saw it two ways. He could give in now and fuck his sister, or hold out and get fucked by one of his sisters. It would end the same way, the only difference being that he had to leave his naked sister and her proffered womanhood behind to manage the second. It was a long road to the same destination and wouldn't do him any good.

Stepping forward slowly, he loosened his pants until his dick sprung out, finally free from its constraints. Sonja couldn't help but stare at it, long, thick, and powerfully erect, mere feet from her. Quickly becoming frustrated at Declan's continued **** despite his resignation, she crawled towards him and put her face up to his cock.

Declan could only watch as Sonja pressed her nose against his throbbing sex and inhaled deeply, visibly savoring the scent of his aroused musk. He desperately wanted to plaster her face with cum at that very moment, but some remaining modicum of decency held him back. Not that it mattered. Sonja didn't need his willingness, just his compliance.

"Hold still, little brother. Your big sister will take good care of you and this big dick of yours. Throb if you understand." She opened her mouth and pressed her soft tongue to his shaft as soon as she was done talking, making Declan's member jump at the soft sensation. Sonja giggled and chased after the tip, flicking her agile tongue against it. Declan groaned as she teased him more and more, one of his hands burying itself in her hair, though if it was to pull her closer or push her away, he didn't know. The only things he was certain of was that Sonja's tongue on his cock felt incredible and that she was enjoying it immensely.

"You're like a virgin getting his first blowjob," she cooed, teasing him a little bit more as she watched his expression twist and contort under her touch. Her hand rested at the base of his shaft, ready to squeeze and stroke him as needed. For the moment though, her attention was focused at his tip rather than his base.

"I'm not a virg-ggnnnnhhhh!!!" Declan said, or tried to, his words turning into a blissful groan as Sonja started sucking his dick into her hot mouth, creeping down his shaft with inexorable slowness and sublime suction. He very nearly filled her mouth with cum at that moment, but was paradoxically so absorbed by the feeling that he could stave off cumming for the sake of feeling more of it. Still, his balls churned with his load and he knew he couldn't last forever. Though the look in Sonja's eyes as she reach the halfway point on his dick told him she definitely didn't want him to hold back.

Unable to imagine anything better than Sonja's lips and mouth blowing him gently and earnestly, Declan didn't do anything but stand there, reveling in his oldest sister's skilled blowjob. He didn't know how she was so good, if she had just had that many lovers and practice or if the airborne Contagion had affected her mind somehow, giving her the knowledge. At the end of the day, it didn't matter, so long as she kept putting that incredible skill to work.

He was so wrapped up in her ministrations that he almost didn't notice her eyes darting towards the door, a look of warning and victory shining in her eyes while her lips were sealed around his turgid dick. The speed of her blowjob increased a second later, nearly driving the thoughts from his head entirely, but he managed to hold onto them.

"What are you....looo~ooking at...?" he asked breathlessly, his focus divided quite unequally between talking and his sister's blowjob. Sonja seemed to smile for a second, an act impeded by the amount of cock in her mouth, before pulling away from his dick with a cute *pwah*.

"Just reminding my sisters about our deal," she said, using her hand to stroke his saliva-soaked shaft. The confusion on Declan's face, though obscured by pleasure, seemed to be enough to get Sonja to explain. "We made a bet. Whoever of us managed to seduce you first got you all to themselves without interruptions. Weren't you wondering why they weren't diving for your dick now that it's in the open and willing?" He hadn't, her blowjob had been just that good. "Anyways, I get you all to myself first and they have to wait for you to go to them. It's really a shame too, since YOUR DICK TASTES SOO GOOD!!" Something fell to the ground inside with a crash, along with a faint yell of 'no fair!' before the pattering of feet showed that their audience was gone.

"Your sister were all inside, watching me suck your cock and wishing they were me. Wishing they could be on their knees in front of you and shoving your dick down their throats." Sonja quickly went back to her blowjob, pushing more of his shaft into her mouth than before, and with greater speed as well. She meant business now and clearly wasn't going to stop.

"They all want to take your cock too, little brother. All your sisters want to be worshiping your dick just like this, going and going and going until your shoot your thick cum all over and inside them!" Sonja's words came out between bobs of her head, the alternation of hot mouth and cool air pushing Declan ever closer to climax. "We've all been begging for it for days and now we finally get it! Cum on me, Declan, cum in your big sister's mouth!"

He couldn't hold back anymore at that and hunched over, grabbing a fist of Sonja's hair and his own dick, stroking madly. His blonde older sister just moaned and stuck her tongue out, waiting for his cream. The first jet of it shot right into her throat, but she didn't gag or ****, just stayed in place for more. The second and third did the same, but were even bigger. Declan lost count after that and just sank into the feeling of pouring himself out down his sister's throat. Shot after shot disappeared into her ravenous mouth, far more than he had ever ejaculated before, until finally the last dribbles were all that was left, rolling down onto her tongue and face.

"Mmm, so good...Dec, you taste...mmm...so good..." Sonja sighed, shuddering through a minor orgasm from his cum alone. She didn't show it as much, but she lusted after him just as much as her sisters and her desire for sex hadn't abated in the slightest. Leaning back and looking up at Declan, she thrust her chest out. "That's not all you've got, is it?"

Declan's vision seemed to blend and blur for a second, becoming an incomprehensible wash of color and movement, before snapping back together in a drastically different orientation. He was still looking down at Sonja, but she was on her back instead of on her knees, and on one of the living room couches. She was holding her legs apart and staring up at him with an expression that couldn't contain more desire if it tried. Her tits were wobbling on her chest, sloshing back and forth as he grunted and fucked her tight, convulsing pussy.

Declan stopped thrusting as he realized what he was doing, but Sonja immediately started whining and a burning ache appeared in his cock that only disappeared when he started fucking his sister again. She sighed and moaned in equal measure, laying on the couch and taking Declan's cock like it was the fulfilment of everything she wanted. Though given the lust she had been feeling the last few days, it very well might be.

"What...happened?" he managed to grunt out as he pumped his hips, unable to resist her fluttering depths. "I don't...remember..."

"Fuck me MORE!! DICK ME HARDER, LITTLE BROTHER!! YOU'RE SHOO FUUKKING OHHH GODS!!!" Sonja screamed, visibly shaking as she came like a truck. Her pussy gushed around his dick, splattering him with her femcum as she immediately started chasing her next climax. "More, Dec, MORE!!! FUCK ME LIKE YOU DID BEFORE!! RUT ME LIKE A BEAST!!! I'M CUMMING AGAIN!!" Declan just watched in awe as his cool and collected beauty of a sister wailed and orgasmed on his cock, wanting nothing more than to be where she was.

Seeing her shaking body and rapturous expression, watching her cum and squirt like the happiest woman on earth, called out to him. She loved what she was feeling and wanted more. He could give her more. His other sisters wanted this too. He could give all of them more. And in doing so, he could let them make him feel that way too. All of them, wrapped in a net of pleasure of their own making, giving and receiving in equal measure. His sisters were already there and ready. He was the one holding them back. He didn't want that anymore. He wanted to give them what they wanted.

Declan's body bulged and strained as acceptance and pleasure coursed through him. His eyes bulged as the apex of all pleasure he had been feeling was exceeded a thousand-fold and he screamed in rapture as his dick nearly exploded with cum. Jizz flooded Sonja's pussy and womb, overflowing it in seconds with even more gushing out as Declan's dick grew in size. Lean muscle appeared on his body, adding **** to his pistoning hips and making his sister moan all the louder.

Sonja felt the change in him just as clearly as he did, and not just as he fucked her more powerfully. His skin shone and freely admitted love and lust flowed from his eyes. She returned it with equal strength, pouring herself out to him as he finally did the same. Her little brother came into his own as a true man as he came into her with his powerful, cunt-destroying dick.

Fueled by the full power of the Contagion, Declan grabbed Sonja by the hips and lifted her from the couch. She was pulled off of his cock for just a second as he turned her around, then he slid back into her welcoming hole. Somehow, their legs managed to support them, Declan grabbing one of Sonja's arms to pull her into his cock with more **** as she bent forward, staring at the floor with vacant eyes as the other arm slapped onto the wall to hold her up. Her breasts hung beneath her, growing larger with each jet of jizz Declan shot into her cunt.

Sonja could only gasp as her pussy tightened around her brother's thrusting cock, upping the stimulation she felt and making her climaxes hit all that much harder. Her already beautiful bottom half refined itself just slightly, but her tits and waist were what really saw change. The bit of fat on her belly was lessened slightly, redistributed to growing tits that filled far beyond what they had been before. Bigger and bigger, they grew, until they were near the same size as Cora's, though whether they could secure the title of 'biggest rack in the family' remained to be seen.

"Deeper. Deeper! Fuck me deeper, Declan! I want all your cum before you go stick your cock in my other sisters," she moaned, mouth hanging open as she begged for more. "Are you going to fuck them like you're fucking me?"

"I'm going to fuck every single one of them! You've all been begging for my dick and I'm going to give it to each. One. Of. You!" He came as he spoke, his bottomless balls working endlessly to give him more jizz to use. "But first I'm going to make that MILF vibe of yours real! This ass was made to get bred!!"

"Declan, you...you....oooohhhhhhh!!!! Yes, do it, I don't care, breed me, little brother, BREED YOUR BIG SISTER!!" Sonja's cried only encouraged him and Declan buried himself as deep as he could inside her. He orgasmed for the nth time in the last hour, pumping gush after gout of semen inside his incestuous sibling, who only moaned and moaned to be bred more, her massive boobs swinging heavily and big ass smacking against Declan's pelvis.

"Ohh...you.....Dec, yes....I....nnhhh........" Sonja finally couldn't keep herself upright under the **** of her brother's fucking and crumpled to the ground in an exhausted, oversexed heap. Her eyes fluttered as sleep threatened to take her, but Declan's grunting above her kept her awake. She looked up with bleary eyes to see her brother straddling her, still pumping his bigger cock. She gasped as fresh ropes of cum splattered her face and painting it with white. Even that was enough to make Sonja cum a little, gently and satisfyingly, the perfect end to finally getting fucked.

Both Declan and Sonja sighed and felt their consciousnesses slip as they came down from the adrenaline high. Getting what they wanted, whether they knew it or not, had left them utterly drained. Neither one could manage words for a handful of minutes, until Sonja finally caught her breath and managed to whisper with a voice hoarse from screaming.

"Are you going to do that to Cora, Adeline, and Vikki too?" Declan was instantly hard again and his exhaustion became a little bit more manageable.

"Wrong question," he said, shifting onto his forearms to try and lift himself. Impressively, he managed it.

"What's the right one?"

"'Who's closest?'"

"To what? To us physically, to cumming, or to breaking down entirely and jumping you like a mess of sex and lust?"

"Does it really matter anymore?"