Nellie's Nanite Infection

It has changed, the previous petite mound thickening and growing into a mountain, capped with a thick clit the size of Nick's thumb. The two sets of lips had become broad enough to force Nellie's legs apart, or cause her to shudder at the sensation as they rubbed together, eagerly eating any panties that they could find that would fit her body. Moisture constantly beaded along their folds, and it released a heady musk that left Nick hard and eager to please. Her body hair had fallen out, leaving it smooth, while her hormones left almost always ready.

Nellie gently grabbed Nick by the shoulder and pulled him gently but inexorably closer, her naked slit beginning to drip as he slowly started playing with her mound. His knuckles started tracing her lips, teasing them apart as her clit hardened, becoming redder, more prominent. Nellie's smile took on a predatory glint, and she started pulling his head in to suck on the sensitive spire, as his fist started pumping in and out, his other hand starting to stroke his own length. He could feel her tightness slowly give way, as her constant low level of arousal built and she coated his arm in her fluids, her scent filling the room.

Nellie started grinding against him, pressing down against his invading arm, playing with her breasts, gasping in time with his sucking. It wasn't going to take long, she'd been on a hair trigger all week, and she needed to head to the hospital soon anyway, for the next stage, but for now, she fucked her boyfriend with all her might, her muscles, her size, and her overwhelming need.

Nick sensed that she was getting close, the rhythmic tension in her cunt was getting stronger and less consistent, as she started to lose control. He sucked harder, pumped faster, and braced his legs as she started bouncing, the floor complaining as she really got into it. A few moments later, she went rigid, hand over her mouth as she bit back a cry, and Nick was blasted by a stream of girlcum. He blinked a bit lazily, enjoying how much pleasure he gave his girlfriend, and the heady musk that left his head spinning.

Nellie knelt down and hugged him gently. "I can't wait to use your entire leg..." She murmured into his ear, and his cock jumped at the image.

***

...

From 2.5 meters to 3 meters is, surprisingly, the period with the highest incidence of injury and negative outcomes. The nanobots are conducting the greatest changes, coating then replacing the bones with a carbon fibre-like material, improving the capabilities of the nerves, and altering the metabolism to function at a significantly greater size. If any of these do not occur properly, medical intervention becomes necessary.

...

***

Nick was waiting outside the hospital for Nellie. She'd been off limits for the last few days, something about how she couldn't afford any unregulated changes in hormone levels, so he'd been helping move her stuff to her new dorm room. The administration had finally agreed that she was too big for the regular one, after her legs and knees dangled off the end of the bed and she could press her head against the ceiling if she went onto tip toes.

Now that she was half a meter taller, they'd finally managed to get a specialized living area ready for her, with oversized... well, everything. Higher ceilings, larger light fixtures, special keyboards, closets, toiletries, and everything else. The only thing he wasn't mostly satisfied with was the clothing. Baggy sweats and t-shirts, but they couldn't do much better until she reached her final size. He'd left a pair with the nurses, and they'd told him she would be ready soon but...

His jaw dropped as Nellie managed to squeeze her way out of the front door. She saw him gaping, and blushed, covering her face a bit. It might have been meant to hide, but with her new body, it just accentuated her form. She'd filled out, going from strong but stick-like to amazonian, her arms straining her shirt, her breasts and nipples clearly outlined, her pants tight against her hips and ass, loose against her waist.

She smiled at Nick's reaction and started jogging towards him, her disproportionately large feet leaving clear outlines in the grass and dirt, though not much deeper than Nick himself would have.

"You... you look amazing!" He managed, running a hand along her rock hard thigh, head even with her belly button.

She knelt down to him, until they were looking each other in the eyes. "And I'm going to keep getting even bigger. I'm only half grown." Her massive hand, big enough to palm his head, gently wrapped most of the way around his thigh, one finger playing with his tent.

Nick groaned at the image, excited to keep helping his Amazon.

***

...

From 3 meters to 6 meters, the new SNU-5|VU continues to grow at a rate of nearly a meter a month, gaining several tonnes of mass, their hormonal profile pushing them towards the intended combat role by promoting muscle growth and increasing sex hormones. Various primary and secondary sexual characteristics may be enhanced as a result. Aggression and sexual domination are also common.

...

***

Nick sat in the middle of Nellie's bed, about a quarter the size of a tennis court. She'd finally stopped growing, and was planning a long night to enjoy her new size with her boyfriend in celebration. He was less than a third of her height, barely coming up to her knees, and was acutely aware of that difference. They'd been spending more time apart recently, she'd been trying to catch up on schoolwork and he'd been... well, it was hard to compare the minor definition he'd gained to what had happened to her. He shook his head, focusing on the present. He heard a knock, and practically jumped up, eyes fixated on the door.

Nellie stepped through, quiet on the polished concrete floor, and smiled down at him. She was huge, over 6 meters tall, multiple times his own height, large enough that people missed her because their brains were programmed to think she was a tree or building or something. Her bare feet padded softly towards him, slowly removing her rain slicker, exposing the perfection underneath.

It was difficult for Nick to really wrap his head around it, no matter how many times he went to sleep between the valley formed by her cleavage, massaged her feet, taller than himself, or tried to wrestle with individual muscles stronger than his entire body. Her form was designed to go one on one with tanks and mechs, against him, even playfully, she dominated him in every way.

And he couldn't deny how much he loved it.

Her toned form, still wearing the cheap clothes while she ordered stuff more appropriate to her final shape, bulged and curved perfectly, the t-shirt pulled taut against cut abs, stretching across hill like breasts, with hard nipples bigger than Nick's fists. Further down, her curves were exaggerated, and she delighted in it with a belt that clearly wouldn't fit across her hips and ass.

Nellie paused, enjoying Nick's near worship, and ran her hands up her body, cupping her breasts, and showing off her stomach. "You want to see more?" She asked, a hint of a smile playing around her mouth. He nodded, mouth dry, cock tenting his pants.

She grabbed her top and strained for a moment, easily ripping it in two, her boobs bouncing in the sudden freedom, as her arms strained the sleeves, stretching it and causing the cotton to crack in protest. She grabbed her pants and did the same, her improved skin, muscles, and bones easily overpowering the millions of threads. She stood before Nick, naked and loving it. She was dripping, her scent already beginning to fill the huge space and she sauntered over to the massive bed, slowly lowering herself next to her little mountain climber.

Nick was achingly hard, but stayed clothed, Nellie liked playing dress up with him. He leaned back, trying not to roll into his girlfriend's depression in the bed, but started sliding, as she spread her legs. She started playing with herself, fingers nearly as long and thick as Nick's arms spreading her slit, and Nick clambered onto her toned stomach, then started crawling towards her prominent clit, an erect ball bigger than his fist. She chuckled, the vibrations running down her body and causing him to shake.

"Let's get you into something more comfortable." She murmured, her massive size meaning he could hear her easily, as her hands reached for him, helping him pull his clothes off. He frantically unzipped and unbuttoned his pants, as she began to gently tug. It was difficult for someone of her strength to tell the difference between gentle and clothes ripping, and he barely managed to pull them off enough that they slipped away, turning dark with her arousal still on her hands.

Finally, he was naked, laying there on her pubis mons, gasping in excitement as her hands started playing with him. He hugged a finger tightly, and shuddered as another stroked against his erect cock. She gently let him go, and started playing with her own breasts, stroking her nipples as the smell of arousal thickened and pervaded Nick's entire world.

He reached her clit, and slowly lowered himself to the ground, finally able to look up at his much larger lover. She gazed back, a mixture of love, adoration, and naked lust in her eyes, as her erect nipples promised a long, wet, enjoyable night. He was sure his expression promised the same, and looked down.

Her slit had continued becoming more prominent and demanding, the outer lips almost parted due to the sheer heft of the minora, her clitoral hood barely able to contain her huge bud. He ran his hands through her arousal, one hand playing with her nub, sending a tremor through her and the bed, the other reaching inside and playing with her g-spot.

"Oh, fuck... you can play me like an instrument." she moaned, her muscles tightening, then starting to undulate, gently contracting around the invader, pressing against Nick.

Nick grinned and began thrusting, his cock rubbing against his girlfriend's lips, mouth and hand playing with her clit.

She was still on a hair trigger, and rapidly shivered with a small orgasm, splashing Nick's front, the first of many to come.

***

By the end of the night, Nick and Nellie were both exhausted, covered in fluids, and cuddling together, Nick nestled between Nellie's breasts.

"That was amazing." Nellie gasped, pressing her arms to her side and enveloping Nick for a few seconds. Nick relaxed in her warm grip, and Nellie let him go before he started to gasp for air.

"I'm glad you thought so." Nick said. "Tasted different tonight." He said, licking her girlcum slick chest. "Bit harsher than usual." He chuckled, and Nellie froze underneath him.

"What's wrong?" He asked, looking up at her confused.

She paused, as if weighing something. Then looked down at him, a smile playing around her lips. "Well... how do you feel now that you're infected by SNU-5? I'd love to do a study on the effects on a male."

Nick stiffened on her chest, then relaxed. Well, one part remained stiff. "I think I'd love that." He said.

***

Need to say thanks to xkcd's What-Ifs for giving me a rough idea on the scales actually employed here. Volume will never not break my brain.

Requested by blackusurp