"You say I must choose one or the other," Anya said, "but you are mistaken. I want both, and I am going to have both." Jeff started to protest, and Anya said, "Shut up and watch."
Anya grabbed her left thigh with both of her hands, and pulled on it, hard. Her entire leg separated from her torso at the hip joint. "It's heavier than I expected," she commented. "Hold onto this for a moment," she said, handing her leg to Jeff. His eyes bugged out, as he took the disembodied leg. He shifted his grip on it, looked at it from different angles, and seemed fascinated by holding a detached body part.
"Quit ogling the leg and watch me," Anya told him. She awkwardly stood up on one leg, using a hand on the arm of the sofa for support and balance. At first Jeff wasn't sure what was happening, but as he watched, something started growing from her empty left hip socket. It quickly became obvious that she was growing a replacement leg. In just a few minutes the leg grew to full size.
"Now, what to do with that?" she asked rhetorically, pointing to the disembodied leg. "Better give it back to me," she said, and took her old leg from Jeff's hands. She ran one hand up and down the leg, then across the bottom of the foot. "Oooh, that tickles!" she said, almost dropping the leg. "Just kidding," she added. "My doll form don't seem to be at all ticklish. A pity." She set her spare leg on the sofa, lengthwise.
As he watched, something started growing from the leg. It didn't take long to see that it was, in fact, a small torso, looking comical in proportion to the size of the leg. Soon the torso reached matching size. Jeff was embarassed, as the torso became anatomically correct. He looked away, but Anya grabbed his head and turned it back to the growing body. "You wanted me to be your fuckbot, so this is no time to get embarrassed about seeing my naked body." As he watched, another leg, two arms, and a head started growing from the torso. Before long, there was an entire body, as far as he could tell an identical duplicate of Anya. The duplicate body stood up.
"There are two of you!" Jeff exclaimed.
"There's only one of me," Anya corrected. "I just happen to have two bodies," the other body said. "So despite your insistance that I can only be one or the other, I am going to be your sister AND your fuckbot."