Sister Transformation Story (Commission)

Thanks to Wildcrino for this story Commission. Also thank you for the great art work to inspire the story.

Sister Transformation

“No way!” Timmy cries out as Tiffany pulls him. “Your sister will shout at us!”

“She’s gone out,” Tiffany replies as she grips his hand tighter. “We can go play with all her grown-up stuff!”

Timmy pulls his hand from Tiffany’s and stops still in the middle of the hallway. Looking around nervously, he leans towards Tiff and whispers.

“Are you sure it’s going to be ok?” He asks. “I don’t want your mommy to tell us off again.”

Tiffany giggles and takes hold of his hand once more. With a sharp tug, she starts pulling him in the direction of his sister's room.

“You wanna be best friends with me and play house with me right?” Tiffany questions with a giggle. “My sister won’t mind if we play in her room. She told me we could.”

Timmy does his best to keep up, as her long dark hair flicks him repeatedly in the face as they walk. Tiffany then stops outside of her sister’s room, lets go of his hand, and turns to give him a huge grin. Straightening her frilly pink dress, she opens the door and pushes it wide open.

“I was thinking we could both be mommies today,” Tiffany says as she steps into the room with confidence. “Just like David’s family. He’s got, two mommies!”

“Be a mommy?” Timmy enquires as he follows her into the room. “Does that mean I need to dress up?”

“Yes!” Tiffany quickly replies.

Strutting into the room with purpose, Tiffany throws open her sister’s top draw and grabs an arm full of her underwear. Throwing it down into a pile on the floor, she looks at Timmy with a devious grin.

“This is going to be fun!” she cheers, jumps, and claps with excitement. “We can’t be mommies wearing little children's clothes can we?”

Timmy looks down at the colorful and strange-looking underwear on the floor. Anxiously rubbing his arm, he gives Tiffany a worried look.

“I’m not sure,” he comments with concern. “Your mommy got so angry when I wore one of your dresses. I don’t wanna get shouted at again!”

Pouting her lips, Tiffany makes it look like she’s about to cry. Stomping her feet, she starts letting out loud whimpers.

Timmy knows what will happen if she cries. He will get the blame and will be forced to take a time out.

“Don’t cry!” he shouts and instantly sits on the floor.

Removing his socks, he looks up at Tiffany’s smiling face. “You’re going play dress-up too?” he asks.

Tiffany nods her head and jumps up and down on the spot.

“Yeah!” she cheers. “I can’t be a mommy wearing one of my dresses. I want to wear grown-up stuff!”

Tiffany bends down and picks out a random piece of her sister’s underwear. She holds the large black bra up and looks at it with an excited smile.

“What's that?” Timmy asks, pulling a bewildered expression. “Is it clothes for mommies only?”

Holding the large cups up against her chest, Tiffany nods at Timmy in agreement.

“If we want to play mommies,” she comments and points down at the pile of underwear. “We have to be wearing one of these things. I always see my mommy and sister wearing stuff like this. Maybe you have to be wearing one to be a mommy?”

Intrigued, Timmy reaches over and pulls out a similar-looking bra. Pulling it from the pile, he smiles at the dark red color.

“I like this color,” he says as he dangles the large underwear in front of his face. “Do I have to wear this to pretend to be a mommy?

“Yes!” Tiffany replies giving a wide-eyed grin. “We need to get out of our kiddie clothes and into my sister's grownup stuff.”

Tiffany starts unzipping her dress and quickly pulls it off. As she throws it down to the floor, she stands in front of Timmy with just her frilly pink underwear. Her hair is a complete mess and she had to blow a chunk of it from her vision.

“This is going to be fun!” She exclaims. “I’m going to be the working mommy and you can be the stay-at-home mommy.”

Tiffany looks so excited and Timmy doesn’t want to miss out on the fun. He quickly stands and follows her example. Removing his shirt and shorts, he discards them to the floor. Standing timidly in just his Y-fronts, he watches Tiffany navigate how to put on her sister's grown-up underwear.

“Do these pads keep your sister’s chest warm or something?” Timmy asks as he looks at the deep red bra he picked out of the pile.

Tiffany doesn’t answer. She’s too busy working out how to do up the clasp. Sticking out her tongue and concentrating like mad, she finally does the clasp up and the bra loosely hangs from her shoulders.

“Look!” she cheers “I got it on! Do you want help with yours?”

Embarrassed, Timmy holds out the bra towards Tiffany wanting her help. With a super-wide grin, she quickly takes hold of the red bra and soon has his arms in the strap.

“Ready to be a mommy?” Tiffany asks as she does up the clasp.

Timmy looks down at the bra and how it dangles from his body. It’s so big for him, the pads almost reach down to his stomach.

“I feel funny,” Timmy says clutching his body. “Is it supposed to give me ouchies?”

Tiffany moves around him and turns her attention to the pile on the floor. Giving it a moment or two of concentration, she reaches in the pile and picks out the matching panties to go with her bra. Turning to Timmy, she holds them up and smiles.

“I don’t think it’s meant to hurt,” she comments. “I have heard my mommy and sister talking about how their underwear needs to be matching though. Maybe you need to find the matching set?”

Tiffany swipes hair from her eyes and sits down on the floor. She pulls her frilly panties off and threads her legs into the large opening of her sister's black panties. As she stands, the panties almost full away from her narrow hips. Giving out a nervous giggle, she grabs the panties to stop them from falling down.

“Do I look like a mommy?” she playfully asks.

Through his discomfort, Timmy gives her a small smile and a gentle nod.

“I see the matching one for you,” Tiffany smiles and points at the pile. “Maybe wearing the matching set will make it not hurt?”

Timmy didn’t give it much thought. Since putting on her sister’s bra, his body ached and he was hoping that Tiffany’s idea would stop the pain. He quickly sits down on the floor and outstretches his legs. With a bright red face, he slowly pulls down his underwear and covers himself so that Tiffany won't see.

“I saw it!” she screams and giggles. “I saw your pee-pee!”

With his face going even brighter red than a ripe tomato, he snatches at the matching red underwear that Tiffany had pointed out. With one hand covering himself and the other trying to run her sister's underwear up his legs, he lets out a moan.

Giggling, Tiffany really enjoys watching him awkwardly pull her sister's underwear.

“You’re a mommy now too!” Tiffany says clapping as Timmy gets to his feet.

Awkwardly standing and having to hold the underwear up, he gives her a sour look.

“Tiffany!” he whines. “My body really hurts. I don’t feel right!”

Looking at the pain in his expression, Tiffany looks around the room and wonders how she can help him. Seeing the stockings and garter belt that go with the underwear he already has on, she snatches them from the floor and holds them out.

“Don’t worry,” she says to comfort him. “I’ve seen my sister wearing those and I know you need these to complete the set.”

Timmy holds out his hand and looks very confused at the odd garments. He’s never worn stockings before and has no idea what a garter belt is.

Holding up the garter belt, he shakes his head.

“Where does this go?” Timmy asks. Does it go around my neck like a scarf?”

Tiffany shakes her head and points at his hips.

“Do you want me to help?” she asks as she snatches them from his hands. “I know smelly boys don’t usually wear tights.”

Giving her a bashful nod to say please, he soon finds himself sitting down on the floor with Tiffany running the clothing up his legs. She soon as stockings up his legs and the garter around his middle.

“These are too big for me!” he whines “The pain hasn’t gone away either! I think it’s getting worse! My body feels like it's stretching!

Tiffany helps Timmy back to his feet and loves what she sees. The clothes barely fit him but he looks just like a Mommy. She claps and gives him a huge smile.

“I think you look great as a mommy!” she exclaims. “Look, they are even starting to fit you now!”

He doesn’t need to look down at himself, he can feel his body expanding and growing. His face starts going pale with panic, as his body tingles with the sensation of exponential growth.

“I’m not feeling well!” Timmy then groans. “I think I want my mommy!”

Very concerned with the sensations coming from his body, Timmy doesn’t notice Tiffany crying out with pain also. He focuses solely on the burning sensation he feels on his chest.

As tries to move the bra away from his chest to investigate, a massive jolt of force pulls him forward. As he steadies himself, he looks down to see his chest swelling and ballooning.

“I want my mommy!” he cries out in agony as his chest swells and quickly fills the bra with two large very feminine mounds.

The weight of his large breasts causes him to wobble off balance. He’s a young boy and he has no idea how to hold up these large breasts hanging from his chest.

Grabbing for some nearby furniture, Timmy quickly realizes that he’s much taller than before. Looking at Tiffany, who’s holding her chest in pain, he can see how much taller he’s grown. His legs stretched so long and smooth, he didn’t recognize them as his own.

“Tiffany!” he cries. “I’m scared!”

That’s when he feels something tickling his shoulders, neck, and back. Quickly turning his head, sways of long hair fall in front of his face and all around his shoulders. Shocked, he swipes hair from his face and tries pulling it away from his body.

“Ouch!” he exclaims as pain ensues from his tugging. “I don’t want girly hair! I’m not a girl!”

Like a bolt of lightning, a scary thought crosses his mind. There was now no mistaking that the underwear Tiffany had made him wear was fitting to his body like a glove. He could feel his body being heavier and plumper. Not only was the weight around his chest obvious, but the weight around his hips and tighs too.

“Wheres my pee-pee!?” Timmy cries as he awkwardly reaches down to his crotch desperately trying to look past his large breast. “I can’t see it or feel it!”

The blood drains from his face as his fingers lightly touch his freshly transformed privates. His supple and sensitive vagina sings with new sensations as his fingers brush over the lips. He could feel every inch of the soft panties he had on. They fitted his body perfectly, almost like they were made from him.

“Timmy?” Tiffany questions, causing him to look up. “Is that you?”

Swiping the swaths of long hair from his face, he gently nods.

“Tiffany?” He then replies as the spitting image of Tiffany’s sister looks back at him in confusion. “You look just like your sister!”

As he looks at her in complete shock, Tiffany stands proud and pushes out her large chest.

“I do?” she asks with a playful laugh. “I feel really grown up. My body feels really heavy!”

“…..Yeah….you do!” Timmy replies in complete shock. Then he takes another look down at his newly transformed feminine body. “Have you seen what's happened to me! I’m not a boy anymore!”

Tiffany pulls a face and quickly looks down between his legs. With a smile and a clap, she bounces on the spot. Her large boobs fail around as she jumps for joy.

“You don’t have a winkle anymore!” she cheers. “Now we are both ladies, we can be better than best friends!”

Timmy looks at her bewildered and confused.

“I don’t understand,” Timmy says as he moves around in his new female body with discomfort. “I can’t be sure, but I think I look just like my sister now.”

Reaching for some black panty house and gently running them up her now long slender legs, Tiffany turns to him and smiles.

“Well….,” she says. “Now you’re a girl, we can do more things together. We can have sleepovers, play pretty princesses, do each other's makeup, braid each other's hair and talk about boys!”

A shiver runs down his spine as he stands awkwardly trying to get used to his new body.

“Don’t worry!” Tiffany smiles and finished putting on the pantyhose. “I will teach you all about being a girl.”

“You will?” Timmy answers bashfully. “What about our sisters? Won’t they notice that we have transformed into them?”

Tiffany shakes her head and laughs. “No,” she swiftly answers. “They may have had a small transformation of their own!”

Timmy looks at her again with more confusion.

“Transformation in what way?” he asks.

Tiffany picks up the small pink frilly dress that she was wearing before. Holding it up against her much larger feminine shape she giggles.

“My sister will now likely find this dress more fitting!” she answers with a sinister grin