Kate and Lucy were two normal sisters. Sure they fought on occasion, but they were both relatively respectful to each other. Lucy looked up to Kate. She had a perfect body for her age. Kate was everything Lucy wanted to become. And as for Kate, she loved Lucy and was someone who would do anything for her, as long as she wasn't preoccupied with friends. Little did she know that she was going to do for Lucy something that would have seemed impossible in a normal family, But this family was anything but normal.
It all started innocently enough. "Hey Katie, could you help me with something?" Lucy asked her big sister. "Sure. Let me just finish making plans with my friends." Kate responded. They were the only members of the family in the house at the moment, so Kate figured she had plenty of time before one of the adults came home to watch Lucy, before she could go out. Lucy waited patiently for her to finish. "So yeah... Yeah... 5 sounds perfect... Okay then... See ya later Ron." And with that Kate hung up. "Hanging out with your boyfriend?" "How'd you guess... So what do you need help with?" "The heat upstairs stopped working. Could you see what's wrong with it?" "The heat...? Probably be better if Joe or Dad did it... but I'll see what I can do." Kate moved upstairs and into Lucy's room were the heater was located. Lucy followed her. "Let me see. Kate took a look at the heater controls. Nothing seemed out of the ordinary. "Well let's try to move it up a bit." Kate fiddled with it a bit and heard several clicks. A few seconds later, the room temperature started moving up. "Seems like that fixed it." Lucy said. "Yeah... I wonder what was wrong with it." Kate though to herself for a few seconds before motioning to move out of the room. But before she could leave, the room temperature seemed to keep moving up. "Well that's strange." Kate moved back to the heater again and tried to lower the temperature, but when she did it no longer made a clicking noise and the room continued to get hotter. "Wow, its really hot in here!" Lucy said. "Gonna... gonna take of my clothes..." "Good idea... Think I'm gonna do that too." Kate replied. They then began to strip, both unable to realize they were not acting normal. Several seconds later, they were in nothing but their underwear. "Katie... Why did we strip?" Lucy regained her senses enough to ask. "I... I don't know... It just happened...." Kate wasn't feeling like herself. She felt lightheaded, like her body was no longer her own. "Ooh... Katie I don't feel so good." "Me too... What's going..." But before she could finish her sentence, it happened.
"Katie..?" Lucy asked. It felt like she had butterflies in her tummy. "Lucy..." Kate felt heavy, like something was pulling her down. She looked down and was greeted with an impossible sight. Lucy's feet were growing. Her toes were moving away from her heels. "Lucy, you're feet!" "My feet?! What's happening to my... Ah! Katie! Your feet!" "What?! No way!" Kate looked down more and was shocked to see her own feet were shrinking. It felt like her toes were pushing into her skin. "Gah! Agh!" Kate winced in pain as she caught a glimpse of her red nail polish disappearing. Meanwhile as Lucy's feet continued to grow, her toes became an unnaturally bright red. She wiggled them just to see if they were really hers. "Katie! What's going on?!" "I don't know. I don't... Whoa!" All of the sudden, Kate saw her face move closer to her feet. "Ah!" Lucy yelped. She watched as her face moved away from her big feet. They both looked up at each other again. "AH!" They both yelled out. Before Lucy's eyes, Kate was shrinking. Her legs sunk into her ankles and her torso was following. It was even losing it's width. Kate's bra looked loose over her body. And before Kate's eyes, Lucy was undoubtedly growing. Her legs and torso shot up. The leftover baby fat was melting away as the width of her torso expanded. Her unformed breasts were starting to jut out of her rapidly growing body. Several seconds later... "I'm at Lucy's eye level!" "Katie?! Katie!" Lucy watched in horror as she soon had to look down on her sister. Her arms were moving into her shoulders as her fingers splayed and moved into her hands. The red nail polish on those was disappearing as well. Katie was looking up at her sister as they switched heights. "This can't be happening!" she thought as Lucy's arms and hands grew outwards. On her fingernails, a red nail polish was coming in. "Katie! Are we...?!" "I think we are Lucy! Oh my god!" "We're switching bodies!!" they both cried out. Kate's breast were closing in. She could feel them sinking into her body. Her bra, unable to hold onto her body fell off reveling an A-cup at best. "No! No way!" As quickly as it happened her breasts had vanished completely. She was as flat as a board. Lucy looked down at her chest as her nipples rapidly expanded and sunk down her body. They went from and A-cup to a C-cup in no time flat. The bulbous protrusions weighed her body down as her nipples hardened. "I've got boobies!" Lucy exclaimed as she fondled them. "I've got your boobies, Katie!" "I can see that... Now stop playing with them! That's gross! "Ah! Sorry! Ah! My voice!" When Lucy responded someone else's voice replied. But not just anyone. It was one she knew well. "Lucy?! LuuuCCCyyyYYY!" Kate yelled out as her voice changed, getting higher in pitch, but a pitch that was instantly recognizable. "Oh god! I sound like Lucy!" "Katie! Ah!" Lucy felt her face stretch out. Her hair started to rapidly grown out of her scalp. She grabbed onto it in shock. It soon morphed completely into one Kate recognized. As it happened, Kate could feel her face scrunch up. "Goh! Meh fawce!" Kate grabbed onto her face in pain. Lucy watched as her hair moved back into her scalp. Her face shrunk until it was as small as a little girl, one that Lucy knew all too well. The pain suddenly subsided and Kate let go of her face. Her vision cleared as she caught a glimpse of the person standing in front of her. "Fuck!" Kate said in her little girl's voice. "Katie! You... You look just like me! Omg! You really are me now!"
Before she could respond, Kate felt a sinking feeling in her stomach. "Oh god... Not quite!" "What... What do you me... Ew... Oh... Katie... My stomach feels funny..." Lucy clutched onto her stomach as her pelvic area grew. It ripped apart her barbie panties exposing her prepubescent vagina to the open air. Kate looked down as her pelvic area did the opposite. Shrinking, her panties could no longer hold onto her waist and slid down her legs. Her stomach was was too much in pain for her to even bother covering up her clit covered with adult pubic hair. But that was rapidly shrinking, along with her clit. "Agh... Blegh! I feel like I'm gonna throw up! Katie! Agh! Katie, help me!" "Don't, don't worry Lucy! It will... all be over soon! Oh god!" "Katie... Ow! Ah!" Lucy let out a yelp and jumped up. Katie looked down as blood trickled down Lucy's legs!" "Ah! Katie! My pee hole is bleeding. Why is it bleeding?!" "It's okay! When you grow up... Ah... That will happen to you!" Evidently switching bodies meant they were also switching sexual experiences. Lucy's rapidly maturing hymen had ruptured. As evidence, Kate could feel her hymen form again in her vagina. "Oh god! It feels so weird... Gah! Ah! Hmph!" The rapid changes affected Kate's body more then she could handle as she cummed onto the floor. "Katie?!" "Ah,ah,ah,ah,ah... Ah!" Kate let out one last squirt as she collapsed on the floor. Her transformation now complete. "Katie?! Are you... Ah... gah... my insides... Ahhhh!" Lucy couldn't understand what was happening. Why was her body hurting like this? She could feel her mind get cloudy as her teenage vagina, no longer that of a virgin fully formed. The pain was too much as she let out a grunt and then came on the floor as well. "Ah,ah,ah,ah... What is this?! This isn't pee..." Lucy sunk down as she finished her first adult experience. "Ahhh... But I gotta pee..." And pee she did...