You were in a state of shock at what had happened. How could this be? Your sister growing 6 inches and a pair of boobs overnight? This went against everything you ever thought possible or believed about science. It was incredible, it was terrifying. Most of all, it was intriguing. You wondered if the GrowTech company knew what kind of product was on their hands and your mind raced thinking of all the applications it had. Soon, there would be no more short people as everyone would want to grow bigger. The NBA would probably be dominated by people taller than the hoops. But you were getting ahead of yourself. For now, there was only one person that mattered -- Molly.

You had to find a way to get those pills back from her. She was already a little crazy but there was not telling what she'd do if it meant she could grow bigger. And you had no idea if the pills were addictive or anything.

You crept downstairs, where Molly was absorbed by the fridge, looking for stuff to eat. Her butt swayed back and forth and you felt embarrassed by the boner growing in your pants. She had a great-shaped ass, it was a shame she was your sister.

You looked on the counter but the pills were nowhere in site. Suddenly, the fridge door closed and Molly smiled at you.

"Looking for something?"

"Uhhh..."

"It wouldn't happen to be *this* would it?" She asked, holding up the pills.

"Actually, yeah. I think you should stop taking those, Mol. They could be dangerous and as your big --"

"Big brother? Hm. Mayyybbeee for now, but certainly not for long. Especially since I just took a double dosage of both pills. Mmmm I think I can feel a growth spurt about to come on. Wanna watch "big" bro? Don't think you'll be able to contain yourself when you see these tits get even bigger."

She smirked and looked at your boner before wolfing down a slice of pizza and burping loudly.

Her eyes glittered and she kind of tensed up.

"Are you okay?" you asked.

"It's.. happening... again..."

You were amazed as you saw Molly slowly began to inch upwards. Her bare feet slowly grew bigger, as did the rest of her. As she grew bigger, she seemed paralyzed, stuck in place.Her eyes were transfixed on the ceiling and she looked completely unaware of her surroundings. You saw her breasts swell, they were the size of tennis balls now and getting bigger by the second. Her nipples were hard and they made two noticeable protuberances on her ever shortening tank top. 

Molly stood just below your eye level now. She was probably 5'10'', while you were 6'1''. She had a bit of cleavage showing and her boobs were probably a D cup. She snapped out of the trance she'd been in and ran her hands over her new body, spending a few seconds hefting her tits and squeezing them.

"So, TIm. What do you think of the new me?"

"This is crazy...."

"Mmm I know," purred Molly. She turned around, showing her plump ass that was stretching her shorts to their limit. "I think this thing is big enough to twerk with now, don't you?"

"C'mon Molly, what the fuck. I'm your brother."

"Awwww does my body make little Timmy uncomfortable? Get used to it, if I have things my way I'm gonna be parading this ass and these tits all over town. No boy will be able to resist me. You might be hearing a lot of noise from my room at night, don't let it keep you up. Or do. You seem to enjoy hearing your sister being pleasured."

You were left speechless and even more dumbfounded when Molly extended and hand and patted your raging boner. She grabbed it and leaned in to your ear, whispering,

"Whatever I want, I get. I want you, I'll get you. I want food, you'll get it. I want to grow? I'm going to fucking grow. Got that?"

Her hand was tight on your dick and you felt her nails starting to dig in. Her eyes were looking up at you but you knew it wouldn't be long before you were looking up at her.

"Got it," you whimpered. "Can you let go, Molly?"

"When I want to. You're bigger than I thought, Timmy. Or maybe your sexy sister is just part of that."

She let go at last and took out the pill bottle, tossing back a few more. She laughed, seeing your expression, and went up to her room, slamming the door and playing music loudly. An hour later you got a text telling you to bring her some food and leave it at the door. You initially got mad at how bossy Molly was being, but you remembered what she'd said to you. Might as well give her what she wants, you thought.

You left it outside, as instructed, and went to bed. That night, dreams of Molly filled your head. Nothing prepared you for the changes that would come.