Adam was in the middle of watching porn, trying to get the images out of his head, when a voice nearby startled him.
He turned to see Coral in the doorway, who had soundlessly snuck into his room without him noticing. She held what looked like a stylus in her hand, except that the end was black, textured almost like- "Look, it has a microphone! The controller has voice commands!"
Then, she noticed Adam's cock out. "Woah. What are you doing?"
Not being able to create a coherent answer, his sister crept closer, staring at his 6-inch hard-on. "I've seen them in health class, but they all look so droopy. But this one's big."
There was a beep, and Adam watched as his average cock grew to an even larger 9" hard. Coral reached out to touch it. He swatted her hands away from it. "That's a thing that happens when older boys get… happy. Their penises get bigger."
Coral's eyes flicked to the screen. She scrunched her nose up at the frozen image of the pornstar's massive tits wrapped around a guy's dick as she took it in her mouth. "Is this what's making you happy?"
"Yes."
"Why?"
"Because she has big boobs," Adam gulped. He didn't want to have to explain it further.
Coral snorted. "My boobs are bigger." A beep and her E-cup tits grew into a G. Then a thought dawned on her. "Is that why you stare at my boobies? Because they make you happy? Oh, and that's why you had to go look up her, because you were sad, and you needed to feel happy again. Don't worry, big bro, I can help!"
Coral began to strip off her shirt and bra, leaving her bare, perfect breasts exposed. Adam tried to fend her off, but at the same time, his cock throbbed harder and harder for his baby sister's body. "Stop, stop! Coral, go away, you don't know what you're doing!"
"Yes, I do!" Another beep. Coral's entire demeanour shifted as her mind filled with a library of pornographic knowledge. Her body swayed sensually as she bent over, showing her cleavage. She moved like an experienced pornstar, as her body suddenly gained the ability to perfectly perform any type of sex one could imagine. She knew how her brother looked at her, and she knew exactly how to make him cum.
The ten-year-old bent down and stared into Adam's eyes as she slowly took his cockhead into her mouth. Her tongue swirled around it, finding all the right places to heighten his pleasure. She grabbed her prodigious breasts and squeezed them, showing off how soft and pliable the flesh was, teasing him before she wrapped the globes around his cock and began to move her head and tits in sync with one another.
Coral suckled her brother like a pro, bringing him to the edge and keeping him there as he tossed and turned in his seat, squirming at the pleasure he'd never experienced before. But, before he could cum, she released him, standing up to his height. She placed a hand against the back of the chair, next to his head, trapping him with her body. She leaned in close, letting her breath blow gently across his collarbone before she whispered breathily into his ear.
"You like that, big boy?" Adam nodded, completely lost for words against his sister's dominance. She laughed. "Yeah, you like it. You love my big, huge, enormous tits, don't you?"
She guided his hands to the round globes, and he began to knead the flesh. Coral grinned and climbed up onto the chair, straddling his lap and grinding her ass against his hot prick as she wrapped her arms around his neck. "Tell me what else you like."
In a daze, Adam began reciting features of his favourite pornstars. "I… I like your massive thighs," he whispered. A beep and her thighs grew thicker, two soft trunks that squeezed his own. She shivered. "I like your… massive ass." Her butt plumped up to a large, soft cushion, which pressed against rock-hard dick, sending him spiralling into his fantasies he couldn't being to life.
"I like how you're taller than me, I like how dominant are!" he cried, ecstasy flooding through his veins as he felt his sister grow larger against him, her grip on his body tightening as she forced him into her.
"What else?" she hissed, beginning to nibble down his collarbone, leaving red marks in her wake.
"I love how strong you are, I love how you're so beautiful! I love you, Coral, I worship you!"
"I'll give you something else to worship, big brother," Coral sneered as she pressed him back against his seat, her powerful, muscular thighs holding him in a death grip. "Worship this!"
She impaled herself onto his rod. Her strong, thick walls massaged his cock as she speared herself again and again. Each time, he went a little deeper into her vagina, and she screamed out in pleasure. "Yes, Adam! Fuck me hard with your monster cock!"
The remote beeped again, and Adam felt his cock grow larger still, the foot-and-a-half rod leaving a visible bulge in Coral's toned stomach as she rode him hard. He tried his best to keep up and thrust his hips back into her, but he simply couldn't match his sex goddess sister's stamina. Suddenly, as they were both on the verge of orgasm, Coral paused. Time stood still as she placed a chaste kiss on his lips. "Now cum for me," she whispered.
His cock spasmed wildly, in sync with his sister's orgasm. Torrents of cum flowed into her, filling her up so fully that it began to dribble out around the sides of his dick, still plugging her hole. Coral laid back in Adam's arms, panting as he extracted his manhood from her, before giving him a quick kiss and stretching her long legs.
Suddenly, she was back to being his little sister, and not the sexy dominatrix persona she had become. She giggled and grabbed the mini microphone. "Thanks for the fuck, big bro! You weren't half bad." she chirped. "Hope you're feeling a little more 'happy' now."
She winked at him before flouncing out of the room. Adam stared in disbelief as his muscular, 6'4 sister disappeared down the hall, cum sloshing inside her tight vagina. He looked back down at his python, now just a foot long and flaccid.
Fuck, what had he done?