Sam's eyes popped open wide as he first glimpsed the moon. "Come on, come ON!" he snarled, trying to make the change come quicker, knowing his life was at stake. "Come on, damn it, change," he said to himself, smiling as the moon began to do its job. "You girls are fucked!" He said, smiling as spittle began to run down the corners of his mouth as his fangs blossomed.
"I don't think so, Sam," said Jen to her brother. She felt Gillian's body temperature escalate dramatically, and knew that Gillian's change had started. Jen hugged her tighter, whispering, "Give in to it, Gillian." Jen felt her own body temperature rising, and for a moment thought that she was changing as well, then realized it was her own arousal.
Jen wasn't sure if it was seeing her brother changing that was doing it, or if it was Gillian putting off some form of pheremone, but she realized it didn't matter. All she knew was right at that moment, she regretted not having gotten naked with Gillian. Operating almost as if on autopilot, she slid her hands down Gillian's burning body. Originally, they'd been around her midsection, but now they found their way to the outside of her pubic mound, and began to lightly trace Gillian's labia. Jen felt the first prickle of red fur beginning to blossom from Gillian, under her fingertips, and felt her body beginning to tremble as the muscles began to twitch.
Meanwhile, the moon's rays had finally penetrated the room and reached the bed. Between the moonlight and the performance going on in front of him, Sam's cock stood up as straight as a weathervane, his foreskin now darkening to a grayish color, and bcoming more sheathlike, now blossoming the characteristic red tip. His whole body quaked as the change came quicker, and the wrought iron frame of the bed creaked in protest as he struggled against his bonds, becoming stronger by the second. "YESSSS....YESSSSS!!!" Sam growled, smiling an impossibly wide smile as his face began to force itself out into a leathery muzzle.
Gillian herself was unable to tear her eyes away from Sam's transformation. The only sound she emitted was a rhythmic and gutteral, "Hrrrrgh! Hrrrrgh!..Urrrrgh!" Jen's hands had gone from a gentle teasing,to a firmer massaging, to now an almost frantic penetration of Gillian.
"Yes, yes!" Jen cried, on the verge of climax, even though she was the giver, not the receiver. Jen had never been this horrifically aroused, EVER. She pressed herself as tightly as possible against Gillian, feeling every muscle in Gillian's body spasming. Gillian bent forward as her spine now bowed with a sharp "snap!" sound. There was an odd, wet puckering sound, the sound of flesh reforming as Gillian's body grew new sets of teats, and her vagina began to reshape into a more lupine form, rejecting Jen's fingers from the front, but giving new access from the rear.
A bulge appeared just above Gillian's raised hindquarters, and a red tail blossomed forth. Another gutteral sound issued from Gillian's lungs as her face stretched out and her final vestiges of humanity began to disappear as her forehead sloped back and skull reformed. Jen's own voice began to reach a fever pitch as her fingers now penetrated Gillian from the new angle, first one, now two, now three fingers, ramming in and out, all the while Jen shouting, "Yes! Become the beast! Become the beast!" over and over again.
The Gillian wolf's transformation came to a howling climax, and she leapt upon the still-bound Sam-wolf, who was unable to break free in time. She buried her face in his stomach, ripping it apart, dragging coil after coil of intestines free. The Sam wolf howled in rage and pain, but could do little to stop it. It snapped ineffectually at her, unable to reach. Mercifully, the Gillian wolf tore its throat out next, ending his suffering.