Fun twinning piece, one of my favorite things in transformation! I got this commission with a friend  TheShadowFox16 on FA, and the work was done by  Tomek1000

You can favorite the original here: http://www.furaffinity.net/view/27950501/

The following story is by me:

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It was a hot summer day, the snow leopard Nafster was hanging out with one of his friends; a white kitsune with red markings by the named of Alexis. The heat led to them not wearing clothes, a common practice for anthros like themselves largely in parts to fur covering up private bits. The air conditioning did help, but it did limit what they could do.

Alexis was on her knees looking through an old box of stuff to see if there was anything interesting to mess around with and entertain themselves until the heat subsided while Nafster watched from one of the chairs.

"So you just keep stuff lying in boxes?" Nafster asked with a small laugh.

"Just old stuff, might be something cool I forgot about!" Alexis responded.

"Anything fun you remember putting in there?"

"Not really, but that's why I'm looking! It'll jog my memory!"

"Whatever you say." Nafster chuckled and leaned back.

"...Huh, that's strange..." Alexis commented out loud.

"Hm? What is it?" Nafster pondered back as he pushed himself up and walked over.

"This weird controller." Alexis commented and pulled it out, holding it down for Nafster to see. "Looks like a PlayStation one almost, if it was missing a few buttons."

"Do you know where the actual console is?" Nafster asked with a raised eyebrow.

However, a smile slowly crept onto Alexis' muzzle as she realized exactly what it was. She wondered if it still worked as she hit one of the buttons on the controller, suddenly causing Nafster's body to shoot stiff.

Alexis' grin grew into a full on laugh upon seeing it actually work as she watched Nafster's changes.

Nafster's ears became a fair bit larger and longer, the somewhat circular shape turning full triangular. The outlines of fur around them turned red while the interior turned white as well as around the ear itself. White fur started to overtake parts of his upper torso as well, parts of his neck and shoulders taken over by the new fur color. A little bit traveled down his arm as a red mark wrapped around it. Nafster's tail shot out much longer and looked quite rigid as it began to quadruply.

Alexis' smile turned more smug as she hit another button on the controller to make the changes go faster for the changing snow leopard.

White fur quickly overtook his entire face with a red mark going up his now longer muzzle while his pink nose turned black. His hair started to grow longer, along with his eyelashes. White fur overtook his entire neck, of which became thinner while his adams apple shrank nearly out of existence. His other arm grew white fur fully, a red mark matching his other forming. Starting just past his elbow, black fur over took his normal snow leopard one, not yet changed on the other side. White fur covered all of his upper body save for parts of his chest. Nafster's hips expanded outward, swelling into childbearing proportions as two red markings formed on each hip. Nafster's tails were all long and white, four in total with black tips. The white fur reached Nafster's knees, one becoming black while the other remained gray and spotted. Black claws emerged out of the paws of the changed foot, as well as shapeliness on the changed leg.

Nafster's expression was a mixture of shock and worry, his knees pointing into each other as his manhood started inverting. His still snow leopard arm went across the last of the snow leopard fur on his chest while the other hung dryly. Alexis hit one more button, licking her lips as the final part of the transformation kicked in.

The last of Nafster's snow leopard pattern faded into the white fur at the chest, black at his leg and arm. His figure itself began contorting, Nafster's waist caving inward along with his back while his rear swelled outward. This would leave him with an identical hourglass figure to Alexis. At Nafster's chest, two lumps began to amass. Nafster slowly brought his hands up to them, holding and groping them as a pink mist emitted around his eyes as her mind itself starting to morph into Alexis' own. A somewhat awkward smile grew across the once nervous snow leopard turned kitsune while his hair turned a light black and grew all the way down to her back, some of it falling in front of him at his chest. The last of Nafster that was between his legs completely retracted, contorting into the reproductive system of that for a woman as the Y chromosome was re-written by another X.

Alexis watched with excitement as the transformation seemed to of finished as the mist around Nafster's eyes vanished and the bashful smile grew into a devious smirk. She looked over to her twin with an un-moving expression.

"Well then, just two of the one of us now!" she licked her lips. "Why don't we have some fun?" Nafster turned Alexis said coyly as she went behind the real Alexis, wrapping her arms around Alexis' and grabbing and lifting up her breasts.

"Oh you dirty dog me!" Alexis giggled as she looked back into her clone's eyes. This was going to be fun!