Price of Acceptance

"Quick, draw these on your body. I've found a way for us," commanded Ava handing Adam a paper covered in archaic runes and some jarred dark smelly paste.

Ava began to strip down in front of her brother while painting similarly archaic looking runes on her body. Adam, like so many of Ava's schemes, went along. She was his sister and he too deeply desired a means to be with her that society would accept.

Ever since both shared a small apartment in college to save money they have been fucking like rabbits. Dorm prices went up, cheap apartments became the rage. The only issue was no cool air for those 100 degree days. After a few nights of undergarments only, one thing led to another and Adam was exploring his sister's lady garden with his prick.

Now in Ava's senior year, Adam is working for a PR marketing firm and they want to be accepted as a couple. Their love, in and out of the sack, goes beyond just siblings having a fling.

"Listen, when I light this candle, I am going to start reading this incantation and you start fucking me fast. The effect takes hold when we orgasm. Got it?" Ava stated standing fully naked with her pubic hair wet from her pussy in anticipation of what comes next.

Adam nodded and Ava lit the candle. Her incantation filled the room along with the candle's smoke. Grabbing his sister, Adam thrust his shaft all the way to the base, right into Ava's soaking wet pussy. He thrusted in and out of his sister, blonde pubic hair mashing between the two, and animalistic grunts filling the air.

A slight breeze swirled smoke around the frenzy and the runes drawing it inward. Ending the incantation, the two continued to fuck in a primal animalistic rut. Neither aware of the changes that began to fall upon them. First their eyes went from a sky blue to a dark violet that seemingly glowed in the dark bedroom loft.

Little moans escaped Ava's mouth as her canines lengthen. Two bumps began forming on Ava's temples as Adam continued to drill down into his sister. In a swift action both switched positions with Ava on top in classic cowgirl.

Ava became lost in her own trance not noticing two bumps forming, one on each of Adam's temples. Oblivious of her own changes, those two similar bumps now appeared to be two tiny protruding horns. Her hands were just too busy massaging her tits that had swelled from a B to a D cup. Each hump caused a new moan and her now forked tongue surged forward. Effortlessly her tongue started licking her rock hard nipples.

Louder and louder moans and grunts filled the space. Adam too in a trance, was oblivious of all the changes occurring. Tired of playing with Ava's tits he reached around to grab her ass where he discovered a hard nub at the base of her spine. With each hump he rubbed it causing it lengthen. Soon he was able to firmly grasp it. With every new hump he would thrust up into his sister and give her tail a pull causing it to lengthen more and more all the while Ava's moans grew louder and louder.

Nearing climax, both had a pair of horns that curled upward. Ava, while mindless humping away, could feel Adam's cock change. It had grown in both length and girth with a much more pointed tip. But she didn't care as orgasm was seconds away. Her spaded tail whipped in the air and slammed into her asshole causing a new wave of pleasure. Two hardened spikes shot out her heels as her skin changed to a cerulean hue.

Adam, whose skin was now crimson in tone, was grinding his elongated canines as he thrusted hard and deep into his sister blowing his load. Ava simultaneously orgasmed too, squirting a sweet smelling juice all over Adam's cock.

In that moment the sibling's minds cleared and the shock of reality of what they had transformed into had barely begun to set when a flash of light filled the room. In front of the brother and sister a demonic looking female stood and laughed. Ava went to speak when the demoness raised her hand to silence her.

"I said you would be accepted as lovers, I didn't say where. Now come my children, you have much to learn," said the Demoness extending her hands to both.