Of Course, It's Tittyfuck Time

Claire pulled her face from staring down the barrel of her brother's cock. "Mia," she gulped, "I'm sorry for getting in the way. You're an adult and I don't have the right to make this decision for you. Is this what you really want... to fuck Ryan?"

Mia smiled and crawled over to hold Claire's hand. "You know very well what I want... but this is your decision. I won't make it for you."

She didn't know if this was the cum lust, sisterly protection, or real lust, but she had made her decision. Claire turned back to Ryan and cattily licked at the tip of his cock, "Fuck my titties, Ryan!"

Ryan grabbed the thin straps and pulled the nightie down Claire's sides releasing her jiggly tits from their confinement before gripping the sides of her fleshy mounds and pulling them around his cock. They squished pleasantly against his hard shaft. Ryan thrust back and forth between Claire's perfect tits and felt the warm softness of Claire's extended tongue as he plunged into her open mouth.

Mia held tightly to Claire's hand as she fingered herself to the glorious sight before her.

Ryan was in heaven.

The best part is, Claire choose this. She choose slurping on his cock as he nestled so perfectly between her tits.

What Ryan felt for Mia was a steamy romance. He had loved her and fantasized that they would be together in a secret way, in little looks, in subtle touches, and then quietly in the night they would reveal their love for each other and show each other the affection that they've always had. What Ryan felt for Claire was unbridled lust. Something about Claire had always had power over him, put her above him. That distance filled his fantasies with a more primal display of domination and wanton desire. Now that the slut side had won out he felt the fantasy was now real. At least for now, he would make Claire his cum slut.

"So..." Ryan asked with a smug look, "How big do you want your tatas?" He grabbed her hand and hovered it over her lips.

"Big enough to make your massive dick cum in my mouth." She replied as she stared down his beast.

"Alright then... Mia, take Claire's hand. Now, say the magic words until you are happy with the size of my penis. I'm going to squeeze these boobs around my shaft and you stop touching her hand to her mouth when you can't see my cock."

Claire paled. Her tits would be huge if Mia went overboard. And she seemed inclined to do so.

Mia said the magic words, "Grow Penis Grow," over and over until it looked like a baseball bat and stuffed into Claire's open mouth. At this size her tits couldn't even wrap around it. Then she felt her fingers press against her mouth and tits start to expand. Ryan squeezed her boobs against her shaft as her breasts ballooned outward. She would be more worried if his cock didn't taste so damn good in his mouth.

When she felt her tits were the size of watermelons Ryan said, "Stop. I want to be able to move them easily enough. If you go too big it will be a challenge to get me off."

Mia placed Claire's hand on the floor and resumed her masturbation, relishing in the absurd titjob in front of her.

While Claire's knockers were truly bimbo-sized they hadn't lost any sensitivity. Her body felt warm and tingly as Ryan squeezed her tits around his shaft. She sucked greedily on his tip as he thrust into her. Ryan's hands firmly massaged her tits and after several thrusts he would tweak her nipples just to see her moan. He hardly seemed to care that Claire gagged on his cock. He was focused on making her enjoy being used. Now she had the body for it. An ass that swayed, tits that rocked, and piercings to show her true character. Now she was truly his sex object, not just fantasy.

In her cum haze, Claire didn't mind that she was gagging on her brother's massive cock. She didn't care about the size, only the flavor. She was truly horny now, dropping her inhibitions in exchange for pleasure. Living the moment like Mia was. The feeling of her rocking tits was a bonus, but what she was addicted to, and truly craved was her brother's semen. She knew, now more than ever that she was helpless in every respect. If this game went on any longer she would whore out every virtue she held for her carnal desires. She sucked on his rod desperately. She couldn't turn her head, but she could hear the sound of her sister's sopping vagina as Mia fingered herself next to her. Claire knew that her vagina was just as soaked. She wish she could bring her hand down and do the same. Right now though, she was Ryan's fleshy sex doll, awaiting his completion without a care in the world. She could tell he was getting close and her excitement built as the pressure mounted.

Sadly the box dinged just in time to spoil the fun.