Babysitting my sister

"You grew?" You half ask while stating what you see. Kelsey looked at you in disbelief but her face is beaming with happiness. "Are you playing a joke?" Kelsey asked while her dress pressed into her. Kelsey was aware of her clothes, they felt snug and too small. Kelsey looked up at you and said "I really hope I grow more. It was awesome." Her voice was full of glee and you couldn't resist pulling out the gun. You fire without thinking and Kelsey gasps as she watches the ray hit her. "You made me grow?" She was very pleasantly-surprised sounding. Your face goes bright red as Kelsey gets taller right before you. The buttons on her dress pop off and you can see her flat chest and two darker pink areas of skin that were her undeveloped nipples. Kelsey tackled you in a hug and the force was oddly solid and soft. You could feel Kelsey growing as she laid on top of you. Her skirt was tight around her hips and you noticed the hem rise higher and in moments no longer covered Kelsey's frilly white panties.

You were laid on your back and Kelsey was sitting on your chest, you had no idea how large she was but could feel her firm legs weigh more. She had no idea how heavy she was becoming and simply was enjoying how nice the experience felt. You groan as Kelsey continued to expand on top of you. Her body was causing you to react in a way you were very ashamed of. Kelsey could feel the sudden press of your erection. She turned to look down at your lap and without saying a word she pulled back your pants. You felt very strange as the huge body on top of you was quizzically staring at your boner. Kelsey grabbed your dick and you felt very alarmed but the growing hand felt soft and gentle. Kelsey tugged at you experimentally and you felt a mix of pleasure and shame with each pull. "Kelsey don't!" You cry to no effect as she continues to play with your member. Kelsey let out a surprised gasp as she felt you climax into her huge palm. "Thats so gross." Kelsey said making you feel even more awkward. "Why did you think it was ok to grab my penis?" You asked her sounding fairly angry to mask how helpless you felt. Kelsey's skirt tore down the side as she shrugged her shoulders. She was nearing the ceiling and had to look down to see you. The view was very imposing and you could see her head began to touch the ceiling. "I thought boys only get like that when they really like someone." She sounded annoyed and you felt a chill down your spine as she looked taller. She was having to crouch to keep from hitting the ceiling as she stopped growing. "Does that mean you really like me?" Kelsey asked deviously. You sigh and said "I really like... growing and it is really weird but you growing is what made me like that.

Kelsey nodded. "I am glad you made me grow, I will ask next time before I touch your thingy." the way she said next time made your eyes go wide. "You shouldn't touch me at all, I said I was like that because of you growing." You protest. "I can do whatever I feel like, if I wanna play with your stuff, you really can't stop me." Kelsey leaned forward while holding her arms to her hips making herself look bossy. You felt a pang and realized if she asked you wouldn't stop her. She was now your bigger sister and you deeply were glad she was. "I can't argue, you are much bigger than me let alone any adult on the planet." you said and she seemed to be very proud when she heard adult and planet.

"Good, I am glad you are not being dumb now you made me your bigger sister." Kelsey seemed to take pleasure in the words "bigger sister." You notice her groin is almost eye level from your perspective and can see a slight dampness on her panties. You feel a rush of arousal as you process what you see. You can't resist and give in to yourself deciding to enjoy the moment as it plays out.

"Wow, Kelsey you really have become huge. I bet your the biggest girl ever!" You praise her and notice Kelsey bite down on her lower lip. The spot grew in circumference and Kelsey got very close to you. She was towering over you and her back touched the ceiling. You could feel a light heat from her body and as she pressed her groin into your chest you couldn't do anything as she leaned forward. Her body caused you to fall back onto the ground, unlike before Kelsey felt damp and slick on your chest. Her weight was crushing but she leaned onto her legs and ground herself into you. Kelsey could feel you on her thighs and how forcefully she ground into you made you feel intense. She seemed to be driven by instinct and used your body like a toy. After several moments of her bucking into your chest Kelsey let out a room-shaking moan and then hugged you with her massive arms. You felt like a stuffed animal in her arms and could do nothing as she rolled back and forth while hugging you. She seemed to be basking in pleasure and you felt an ejaculation from how much she rubbed herself against you. Kelsey was giddy in euphoria and you couldn't help but enjoy how happy she was.