He turns his sister into his pet

After a quick visit to the bathroom, John comes downstairs to greet his mom. They have a small talk about how her day went at work. She tells him a story about a rude patient and how her superior doctor treats her.

"Where is Kate?" His mom asks John.

"Upstairs in her room, I guess. She got out of the bath a moment ago. She totally needed it." He explains to her with a smirk on his face as he remembers how his last hour with his sister went.

His mother heads upstairs to welcome her second child and John follows her. They both enter Kate's room. She is still wrapped in a towel with a cum on her face and she's making her manicure.

When their mother spots a dried sticky mess on her face she smiles. "Good to see you've done your job, Kate. Blowing your brother is the only priority in a house for you. Good girl." Kate rolls her eyes in response.

But the last words gave John a wicked idea. What will happen if he turns her into a 'good girl' for a real? Guess he won't know if he hasn't give it try. While his mother is talking to Kate, John opens his new app and quickly starts to generate statements until he ends up with: 'Kate Smith is John Smith's sister.'

"Hope this will work." John murmurs as he changes a word in a sentence into: 'Kate Smith is John Smith's pet sister.'

Applying changes immediately affects his sister. She is no longer sitting on a chair and doing manicures. She is now standing on all her fours, completely naked except for a red dog collar attached to her neck. The cum John pumped on her face an hour ago is still there. Looking down at her naked pussy John spots a tattoo in the shape of a dog paw. Even her pussy lips are now dark, almost black. As she walks around John spots a red tail on her back. It looks so real - it's moving around as Kate sits. Also, her behavior completely changed. She is no longer walking like a human, she walks on all four. Instead of talking, she reacts with barking and body gestures.

Unbelieving what he just did, John asks Mom about her daughter's new condition.

"My dear John. This was the best decision of my life. Do you remember when your sister was younger? She was a brat, never listened to me, had friends, and never paid attention to her studies. And there I have you - my angel, always doing what your mommy says. I was angry at your sister. So one day I found that website that promised to turn your problematic sister into a good obedient pet. So when you turned 18, this was my present to you. The pet of your own that you always wanted, but couldn't have because of my allergy. Now you have your pet-sister. "Isn't that great?" She smiles and pats Kate on the head.

She is kneeling on her legs while she is holding her hands in the air in a typical position for dogs. She breathes with her mouth open and her tongue sticking out. She sits there like a 'good girl' while her mother pats her on the head.

"You mentioned a site, mom. But how is all this possible?" John asks his mother an important question to understand his sister's fate. As his mother is about to answer his question, Kate starts running in circles chasing her tail.

"There's a company that developed a procedure to change humans into obedient pets. Dogs, cats, cows, you name it... The only thing you need to do is to attach this collar around the pet's neck. It will send waves into the brain that change behavior. She also absolved a week of dog training - they literally brainwashed her into it. So even if you remove the collar she will be behaving like a dog. But she will regain consciousness. And we don't want that, do we, Kate?" She smiles over at Kate.

"And a tail? Is it real?" John watches as his pet-sister is still chasing furry tail.

"They also offer more invasive procedures for the body like fur or face reconstruction to remind more dogs. But it was your idea to give her only a realistic tail and plump dark pussy lips."

Kate stops running around and comes close to John. She sits down in front of him and starts hitting John's leg with her nose.

"Looks like your she is asking for a walk. Can you take her?" Your mom points at a dog walk hanging on a wall.