She gave Sarah a familiar vial; Muscle +. Sarah didn't even look at the label before downing it, willing to do anything for Mary. Mary waited for the vial to refill before handing it back to her.
"Again."
Sarah obedienty drank it.
"Again "
Sarah gulped it down. Mary watched as her body started to tremble before force-feeding her another two vials worth. Then, she stood back and let her creation come to life.
Sarah's legs were the first things to grow. The exploded outwards, and an audible crack sounded as her hips widened to accommodate her freight train thighs and oil drum calves. It was strange, seeing her small, lithe torso atop the legs of a greek god, but that was soon to change. Her stomach grew large and chiselled, each of her abs the size of a refrigerator. The pecs that overshadowed them were even larger, musclee the size of small cars keeping her D-Cup tits aloft.
Her arms were next, with her forearms the width of truck tires and her upper arms three times the size. She rolled her enormous shouldere back as a mountain of lats and traps cast shadows over her face. Not to be outdone, her neck grew longer and thicker until it could see over her ridiculously large muscles, her head comically tiny on a body so large.
A problem arose, however, when she tried to move. While the muscle growth had boosted her to a lofty 9 feet, the sheer size of her muscles in proportion to the rest of her body didn't allow for movement. But, Mary had a solution. Climbing over her rock-hard body, she tipped three Height + vials into her mouth.
Mary nearly lost her footing as the impressive woman of pure muscle began to grow taller, shooting up one foot, then two, then three. Her muscles redistributed themselves evenly on her 15-foot body, still the same size but over a far greater surface area. With difficulty, Sarah manoeuvred herself into a sitting position.
"Mary, can I see those vials? I still need help!"
While Mary was unwilling to hand over the box, she understood that she'd never be able to get her goddess if she didn't. Sighing, she passed them over and let Sarah rifle through them. Soon, she found the vials she wanted, and took four swigs of each. While there wasn't a visual cue, the sound of stretching rubber resounded through the room, and suddenly Sarah was on her feet again. The 15-foot muscle god bounced on the balls of her feet, discarding two vials labelled Elasticity + and Flexibility +.
"Thanks, Mary, I feel so much better now," Sarah purred. She twirled around Mary, graceful and predatory, before falling into several poses that should not have been possible with the muscle mass of a freight train. "And guess what I can do now."
Without warning, she wrapped herself around Mary, though not in a hug. Her body twisted and coiled like a snake constricting its prey. From within the rock-solid coils of Sarah's body, she didn't see an arm reaching out to grab the Elasticity + vial again. It was only when she took two more gulps that Mary felt her lust drop to dread.
Sarah unwound herself, far more fluidly than before. She took another gulp, and let out a moan of pleasure. "I would say I'm like Elastogirl now, but I'm far more than that."
She moved herself around, less like a human and more like a fluid. Her form flowed and bent like water. "I can shapeshift, now, darling. I can become anything I want, anytime I want. And, thanks to you, I have muscles enough to crush anything in my path."
She drew herself up to her original, heavily muscled, 15-foot form and towered over Mary. The Amazon looked positively tiny in comparison. "But, let's not worry about that. You wanted a perfect fucktoy? I'm all yours."