Rachel barges her way back inside with no hesitation, moving much faster than anyone her size has any right to, and literally destroying a small section of wall as she does. She stomps through the house with reckless abandon, leaving deep footprints in the floor, knocking posters off the walls, basically making a terrible mess of things before getting to the box of chocolates and tossing the entire box's contents into her mouth and chewing for but a moment before she swallows them all.
"YES!" She bellows loudly as she feels her body shifting, adapting to the chemicals within the chocolates. Not only does she gain bulk tissue, she also gets taller. About seven feet taller. Her head crashes through the ceiling abover her, sticking out through the one-story house's roof, and a simple lift of her arms finishes the job of completely destroying the house.
A small moment of guilt hits her, but it's overridden by the rush of strength, invincibility, she feels. She brought an entire house down on top of her and felt no pain, no ill effects at all.
It takes her but a moment, but something inside her urges her to move. She bends her knees and pushes off, leaping high into the air, soaring, careening over the puny town beneath her. The air cools, tingling along her naked flesh and feels like nothing she's ever felt before. It's the closest a single human being has ever come to flying upon his or her own power.
***
Meanwhile, at the top-secret location, a blip on a monitoring screen brightens from red to pink, and doubles in size, and begins moving towards the center of the screen at a rapid pace.
"Holy crap!" the attendant at the screen shouts, "Sir! She's nearly tripled in size and power and is heading this way! FAST! Should we intercept?"
"Not yet," the commanding officer from before says, an air of absolute calm and control over him. "She's doing exactly what I want her to do. She just doesn't know it yet."