As the serum started rushing through her veins, spreading out rapidly to every corner of her body, Rachel could already feel the effects kicking in. A burning sensation, one that had her grunting and doubling over in pain, stumbling over to her mother's arms. It was like her entire body was burning up from the inside out, reminding her of the hot, tender soreness that always followed a long workout. This, however, was a thousand times more intense, causing her to scream for a moment as it permeated her entire body from head to toe. Concern grew on Veronica's face, but this quickly gave way to relief as the physical evidence of what was happening to her daughter began to show.
She'd always been a slender girl, with a curvature to her rear end and chest that left many people surprised that she was related to San Diego's perfectly-scuplted protector. The embarassment she sometimes felt over this unlucky roll of the genetic dice would never plague her again after today, because she was filling out fast. In fact, her hips and breasts were swelling up so quickly that her underwear just barely couldn't take the strain, snapping and flying across the basement as her already-small black t-shirt was stretched tight, doing absolutely nothing to hide the highly natural curve of her new features nor the nipples trying to poke their way through the fabric.
It wasn't just those parts of her that grew, either. As a hand clamped around Veronica's arm with enough force to actually hurt the near-industructible woman, Rachel's legs, arms, and torso began to lengthen. She'd always been fairly average, five and half feet or so once she'd stopped growing, but in the span of a few moments she gained nearly an extra foot over her previous height. Her eyes opened from a tight squint to find that the ground was a lot farther away... and not just because of how much taller she'd become. No, as a much thicker mane of brown hair fell around her head in a silky cascade, Rachel's bright blue eyes discovered that she was floating, hovering a few inches off the ground.
With the pain subsiding, she was able to relish in a far more pleasant sensation. Power, rippling up and down her newly-changed body from head to toe. She pulled away from her mother, growing excited as she grabbed a random steel tool and easily crushed it in her bare hands. That immense strength, nearly matching her mother's own legendary strength, was what she thought that feeling of power to be... but a crackle in the air informed her that this sensation was a lot more literal. The realization came just in time for her eyes to light up, glowing a soft blue, before her hand was finally engulfed in a dozens of electrical arcs, lightning and thunder rushing through her, imbued into her blood.
The storm abated after a moment, but she remained floating as she looked herself over, feeling up her glorious new curves as the sensation of transforming finally faded completely. "Oh my god!" She squealed with glee, going briefly into a flexing pose. "I got your powers! I'm like... I'l like a Mini-Athena! OH MY GOD THIS IS SO FUCKING COOL!"
Her mother gently tugged her back down to solid ground. "Language, dear - but yes. Yes it is." Next she busied herself with grabbing a towel, throwing it at Rachel to cover up what her failed underwear had left exposed for the whole world to see. "You're going to need a new wardrobe... and we're going to need to take some time to get you acclimated to it. Trust me, just walking around is going to be a little awkard for a few days. You'll need to learn to control your strength as well, and to know how to safely discharge your thunder. Not to mention-"
She was cut off a radio scanner in the basement lit up, reporting a fire across town with numerous people still trapped inside. "Of course," she muttered, before sighing and moving over to the wardrobe containing her costume. "I'll go take care of that, then come back. In the meantime, just start getting used to walking around, and ducking under door frames - I don't want to have to be replacing every frame in this house."
"What do you mean you'll come back?" Rachel frowned. "I should come with you! There are lives in danger-"
"And they'll be in even more danger if you rush in there blind." Veronica was quick, having already slipped into her bodytight costume decorated in California colors, now busying herself with tying off her white cape. "You have no idea of your own power right now. I promise, you'll get to help people soon, but right now, it's safer for me to handle this alone." Now fully changed over into her Athena guise, she stepped over and planted a kiss on Rachel's forehead. "Please, Rach, don't fight me on this."
The teenager sighed. "Fiiiiiiiine."
"Atta girl." She smiled before floating up the stairs, out the front door, and suddenly rocketing off into the sky, tearing through it at near-supersonic velocities to reach the scene. Following her out to the door, Rachel couldn't help but sigh. God, she was a bona fide superhuman now, and her mom still treated her like a little kid. As much as she knew her ass would be grass if she disobeyed mom's directions... there was a huge part of her that just wanted to say fuck it and fly out there to help save the day. Surely more lives would be saved with two superheroes on the case, right? Even if one was a rookiee...