The thing that would wrest her from her passionate embrace would not be exhastion nor lack of interest on the part of Catherine. Instead, they separated as a buzzing sound was heard at the door of the laboratory, and Zhang moved away to attend to this disturbance. Allison was left to lean against a table and attempt to catch her breath, one hand idly making motions up and down her rod as others squeezed at her own quadruple endowments. Terror at her inhuman state had long been replaced with an aroused curiousity, one that still burned even without four powerful arms wrapped around her.
She couldn't quite hear the words exchanged between Catherine and the person on the other end of the buzzer, but she took note as the door swished open and a young woman in absolute shock was revealed. She was prim, well put-together, no older than Allison herself; a nice blouse and pencil skirt hugging her slender body, bright green eyes, curly red hair tied back into a bun. Red-colored lips that begged to be kissed. She wasn't quite so jaw-dropping as Catherine, but this girl was gorgeous in her own right, the mere sight of her causing the shaft in Allison's hand to stiffen slightly.
"You musn't stand there all day, Miss Hawkins. Do come in." Catherine's words, delivered in a more sultry tone than Allison might have expected, were enough to drive the young woman inside, where Zhang promptly closed and locked the door behind her. "Allison, my dear, this woman deserves your thanks. Rachel was responsible for selecting you out of a pool of thousands of other candidates. Without her judgement, you would not have received your gifts..." She purred as a pair of hands massaged her top pair of mammaries. "Neither of us would have."
Considering how poorly things could have gone if she'd been selected by another client, Allison couldn't help but agree on at least one of Zhang's points. "Yeah... I think I owe you a big thanks." She smiled and approached Rachel, finding it odd to tower over the girl as she did - the redhead was easily a foot shorter, with nowhere near the muscle mass, not to mention a single pair of tiny breasts that, combined, weighed not even half as much as one of Allison's or Catherine's. "I'd, uh... I'd shake your hand, but mine are a bit... dirty."
"O-oh, that's quite alright," Rachel quickly replied, her voice sweet, almost sing-song in quality. "I... I wasn't aware Miss Zhang's experimentation would be so... radical..."
Catherine quickly interjected, a pair of hands on each of the redhead's shoulders. "An unexpected result, my dear, yet quite exquisite. You know, I'm glad you arrived when you did - I think you're quite perfectly poised to assist in my research."
Neither woman could question what that meant before Catherine turned Rachel around and began to undo the buttons on her blouse, the young woman offering no resistance. Somehow, Allison got the feeling that Catherine's assistant was accustomed to being handled in so personal a manner. "My lovely doppelganger's fluids have taken on a unique property - they seem to carry a strain of retrovirus which endows the recipient with her gifts." The redhead's top was tossed away, followed by her bra, before Catherine picked her up and carried her over to the table. "At least, this was what occurred when I received it. I simply must know how another individual, one without the genetic makeup we share, will respond to the same stimulus."
Gently she set Rachel down on her stomach across the table, leaving the girl's face positioned perfectly level with her stiffened rod. She opened wide without any need for a command, eagerly receiving her superior's member and applying all the suction power she could manage. Catherine moaned, her eyes meeting Allison as the latter found herself moving without thinking, approaching Rachel's spread legs and ripping her skirt away with ease. She needed no further prompting to plunge her own heavy stick into the girl's moistened folds, producing a muffled scream as her hips tightened down on the new intruder.
As the fire rose inside of Allison, she could already hear particular moans and sounds of flesh pulling and shifting - the residual fluids on both her and Catherine's members had already begun to have an effect, and soon new releases would accelerate the process. Allison found herself enthralled by the thought, forcing her eyes to remain open and observe whatever changes might start affecting the redhead as she squirmed and writhed in pained delight.