Riley stared intensely at her "brother", grinning with a nasty look of anticipation. Jeff, scared beyond belief at what his "sister" could possibly do to him, decided to make a run for it.
"Stand right there. I've realized my current body does not suit a being as powerful being as myself. So as my first test, you're going to become an excellent 'steed' for me." The female Riley giggled.
"Please Riley!" said Jeff desperately. "What are you planning with me! Please don't erase me or something cruel." he kept begging.
"Erase you?" Riley kept laughing. "You see, I've always loved centaurs since I was a little girl, their curious but strong body felt majestic to me, so why not combining them with the king of animals! You wanted to be closer to your sibling, right? I'll help you with that, you'll be alive, just as... a part of ME! Hehe. Now take off your clothes big bro." Jeff quickly stripped against his will, throwing all of his clothes on the floor.
"Wow, nice. A perfect studly body. We're definitely going to have to improve some of those areas though", Riley added with a wicked smile. “Now, get down onto your hands,” she then orders, Jeff does as told. Riley smirks down at him, the alternate version of Jeff's brother starts to take off her own clothes without saying a word.
Riley licks her lips, smirking, “like what you see?” she asks, “let's get to the best part then! I will turn my back to you and I want you to be a good boy and start pushing your head against my ass as hard as you can. I will feel nothing but pleasure, while you feel and smell my ass slowly taking your useless head.”
Jeff is shocked as he finds himself starting to move forward once Riley had turned her back to him. The teen tries to mentally fight for control, but it is hopeless, his face soon connecting with Riley's butt and continuing to push forward, spreading the young girl's cheeks. Riley placed her hands against the wall, pushing herself back to meet Jeff's head, the girl lets out a moan as she feels Jeff's face starting to push hard against her rear hole. Jeff feels as if wants to vomit as his nose is the first to enter Riley's hole, the smell is so disgusting, especially as Riley lets out a little fart on purpose while giggling. The teen wants nothing more then to wake up from this nightmare, 'it must be a dream... it has to be,' he thinks to himself as his head continues to push forward.
Riley on the other hand, is enjoying the sensation, she feels her asshole start to expand and she lets out another moan as she feels Jeff's face and head push further into him. “On-Once Jeff's arms are starting to touch my l-legs... they will start to... mer-merge with them,” Riley mutters between moans, “and I will... have t-total control over... my then lower body.” Jeff's head is halfway in Riley's ass, when the teen feels his hands and arms connect with the back of her legs. He then feels a strange sensation, as if his hands and arms have become goo or slime, and he feels Riley's legs seemingly melting into them, then nothing as he loses all feeling in his arms and hands. Suddenly, with a loud and wet sounding “pop”, Jeff's head vanishes into Riley's butt.
Riley moans as she feels Jeff's hands and arms merge to her legs, she then lets out a loud moaning scream as Jeff's head pops into her ass, causing Riley to cum, squirting from her pussy. The girl takes her hands from the wall and looks down, looking a bulge in her belly that probably contained Jeff's entire head. She then turns her head to look back and a huge grin appears on her face as she sees Jeff's body... or what is left of it, connected to hers. “Now I want my ass to merge with my lower body,” Riley says, “I want to feel as the nerves of Jeff's and my body fuse together. I will feel nothing but pleasure, while Jeff will start to feel his body become numb. I also want his head to start and merge with the inner walls of my bowel, his mouth and entire insides becoming the extension of my bowel making my belly bulge to disappear.”
Jeff can't hear what Riley is saying, but he soon finds himself feeling weird, he feels as if his face and head are melting with the walls of her insides, while his mouth is forced open, melting with the “shit-tube”. The teen is filled with disgust as the stench and taste of Riley's intestine waste fills his former mouth. Jeff then starts to feel his body become numb, his heart somehow stops beating as it disappears, as does his lungs and many of his organs, but he seems to be still alive, Riley just watches placing a hand on her belly feeling and seeing how it reduced until its original size. Soon, Jeff does not feel his body any longer as his entire existence was reduced to a long tube connecting the female Riley's intestines to his (now Riley's) butt, he could only taste, feel and smell her bowel, while barely hearing as the only senses he had.
While Jeff was living through hell, the alternate Riley was overwhelmed by pleasure as she feels Jeff body become hers, Riley smirks evilly as she starts to feel HER lower body, she couldn't care less about what happened to Jeff and the dimension she was, he wasn't her real brother and that wasn't her actual home. The muscles and nerves of Jeff connecting to her system, becoming hers. Riley waits a few minutes, she strokes her new body and grins as she feels Jeff's former penis quiver and start to become erect, “hehe... mine, I've always wondered how it would feel to have one...” the girl says.
Now the new human taur Riley slowly and carefully tries to walk, at first it was a little awkward, but after her brain adjusted she finds herself walking, which soon turns into a trot and lastly into a full on gallop. After galloping a few circles, Riley stops and stands still, “now to finish off my new body...” she says. “I don't need a human penis if I'll have a lion lower body, so, my penis will become longer and the one of a lion but will hide in a fluffy sheath when I don't need it”
Riley giggles as she feels her penis grow as it turns shape, becoming feline-like with small spines in it like the actual animal, a sheath also forms around it while keeping her pussy between her frontal legs. “Perfect,” Riley says, licking her lips, “now, my tailbone will lengthen becoming a lion tail. My feet will become clawed paws and my lower body will then be covered in yellow-golden fur that extends until the hips of my upper body.”
The former human girl, now soon-to-be lion taur, watches as her commands take affect, she moans in pleasure as he feels her tail starting to grow, she watches it swishing happily around as it grows longer and thicker while covering in hair. Her feet morph and become clawed feline paws as a beautiful and bright fur cover her entire lower body. Finally a coat of brown fur grows around the hips of her upper body like a lion mane also hiding her frontal pussy, probably an unconscious effect of having a male lion lower body but Riley just liked it too.
Soon, Riley was just standing in Jeff's room, no longer human, but something much much more powerful. The girl with the lower body of a fully grown male lion grins evilly. “For now, as my last command, I want everyone to act like I'm from this dimension and think that I look normal no matter how many changes I do to me. I have always been a lion taur to them. Also, everyone will remember Jeff, but are unaware of what has happened to him.” Riley feels a slight tremble in the atmosphere as her command takes effect, with a satisfied smirk, the lion taur climbs on Jeff's stolen bed and settles down, crossing her front legs. “I will definitely rule this whole dimension as MINE!" she laughs, "now, what should I do now...” she asks herself, while Jeff was trapped within her new body and his horrible fate.