Loving the story so far. Some side-effects like increased aggression could be really cool though!

Surprised you guys like this one. Maybe I should put it back in the archive but I don't yet have an ending and I might need help with that. I had 3 options. 1. She goes with Cord 2. She makes amends with Mark (I was kind of leaning toward that one since it's so rare in our genre and 3. She leaves to pursue bodybuilding and heads out of her small town to focus on herself for her change.  There used to be a poll option here but I don't see that anymore. Anyway, I have everything done but the end on this one so shoot me some ideas.
-------
A little sheepishly, Sarah left the lab and went out to the floor where she had her best workout ever. She felt powerful. She felt strong– maybe stronger than her husband. That night, Sarah felt her body humming when she came home and joined Mark on the couch.

“Hey, babe,” he said, giving her a quick pec on the cheek but hardly seeing her.

“Hey,” she responded. For the first time in forever, she actually wanted Mark inside her. Instead, when Mark lazily reached for a chip bowl, Sarah reached for it at the same time. Their hands brushed. Mark, startled, flinched as if she’d shocked him.

“Whoa there, careful,” he mumbled, snatching the bowl away a little too quickly. “You’ve been putting on a little size so maybe you should lay off these.”

“And you’re not?” she said, rolling her eyes.

“Fat looks better on a man. We’ve got bigger bones so we can add a few pounds without getting too big."

“I see,” she smiled keeping the secret she held close to the vest.

The tension lingered between them for the rest of the evening.

“You know,” Mark chuckled, patting his slightly paunchy stomach, “getting older isn't all sunshine and rainbows. Especially for athletes. We put our bodies through a lot in our youth, and they don’t always bounce back the way they used to."

“For you athletes, right… Well, I’ve been working out a bit.”

“Yeah, but you’re a woman.” The tension seemed to rise another notch. He looked over and for the first time seemed to notice the new muscle peeking out from beneath her once-flowy t-shirt. Feeling a measure of insecurity, he upped the ante.

“How about a little arm wrestling match to see who’s king of the couch?” They were the words she’d longed to hear Sarah’s heart hammered a wild rhythm against her ribs.

They locked hands. Mark leaned in ready to “win” with a knowing grin on his face. Sarah met his gaze. Sarah applied pressure, her muscles tensing as she effortlessly slammed Mark's arm down toward the coffee table. His smirk vanished in an instant.

Beneath the fabric of her shirt, a subtle bulge formed. Like a coiled spring pressing outward, the swell of her bicep became more pronounced. Veins traced intricate patterns across its surface, pulsing with the exertion.

Mark was dumbfounded.

She held him there, testing her limits, gauging his strength against her own. Instantly, she knew she could overpower him completely. She had thought she might be stronger but now she realized how much stronger she truly was. She was perhaps even send him crashing to the floor with a single tug. She considered it momentarily as he tugged with all of his might. Finally. She decided she wasn’t quite ready to show him his new position in the household. Maybe she could become twice as strong as her husband, perhaps treble. The idea made her wet.

Instead of beating him, Sarah began to wane her pressure allowing Mark to regain some ground. His confidence rose as his arm slowly rose back to the starting position. Then with a casual flick of her wrist, she capitulated and he slammed her hand back onto the coffee table.

“Haha! Knew I could beat ya,” Mark chuckled in relief. Still, he looked a little shaken. “You’re stronger than you look though.”

Sarah played along with a gentle grin. “Wow, you’ve still got it," she said, in mock awe.

The seed of doubt was now a full-blown sunflower in Mark’s mind. Sarah, on the other hand, felt flush and wet in her core. She left Mark on the couch and went to their room hiding a wide grin.
She had beaten Mark. She was stronger than him, though not yet by a wide margin– yet. That would come.

Great Story keep going

Option 1.  My preference is for a relationship of equals.  Cord will help her grow into that relationship.

Option 2.  A relationship with Mark is a reversal of the previous abusive relationship.

Option 3. Leaving town is a soft option and lessens/ prevents character growth

Nevertheless K++ for a great story

  Wook. Here is another section
---
Still, the sensation of being the powerful one in the house overwhelmed her. The aftershock of victory pulsed through Sarah. But it wasn't just the satisfaction of proving her worth. A surge of something hotter, more unexpected, coursed through her veins. She retreated to her room as Mark lay back on his throne in front of the television.

Somehow she portrayed confidence, maybe even dominance in her gait. She reached the bedroom and closed the door behind her. Heat and moisture suffused her body. The feeling was both familiar and new as she was the power broker in the family even if Mark still didn’t want to believe it.

Her hands cupped her pecs and traveled down the expanse of her biceps. She let go of any inhibitions and indulged in the pleasure of her touch. The ripple of muscles beneath her fingertips elicited a shiver of pleasure. Fingers caressed the muscle approvingly, exploring every inch of her body with a sensual finesse that left her breathless with desire. She had built this temple through hard work. Her fingertips danced across her skin.

She moved over to the bed and lowered herself onto the soft mattress. Reclined against the pillows, a sense of empowerment washed over her. She was stronger than Mark. She stretched out luxuriously, her muscles flexing beneath her skin as she savored the sensation of her power. Thick, hard muscles pulsed beneath the surface covered by baby-soft skin. It’s smooth surface was interrupted only by the delicate tracery of veins that crisscrossed beneath the surface.

She removed her clothes in a rush and felt the air caress her skin as she slid under the covers. Running her hands over her body, she explored the firmness and strength she had painstakingly built through countless hours of training and discipline. Her fingertips traced the lines of her muscles, feeling the tautness and thickness in her curves. Delicately she traced every curve and crevice, reveling in the sensation of her sweat-dampened skin.

She let go of any inhibitions and allowed herself to revel in the sensuality of her own body. Her fingers traced the lines of her biceps, feeling the tautness and fullness that she had worked so hard to achieve. She could feel the warmth of her skin, still flushed from the workout. The sensation of her touch sent shivers down her spine, and she marveled at the power and resilience of her body.
When she found the firm swell of her breasts her touch lingered until they found their way to her nipples. Already peaked and sensitive to the slightest touch she quivered with arousal. She teased them with gentle strokes. The heat built within her.

Her breaths came faster now.

Lost in the moment, she let herself be guided by instinct. Her desire grew more urgent and desperate with each passing second. Guided by instinct her left hand trailed down her torso until it found its way between her thighs.

She parted her thickly muscled thighs and offered herself fully to the pleasure that awaited. Her breath hitched as she teased herself and explored every inch of her femininity. The sweet slickness and crackling heat between her thighs grew more intense.

Her movements became more urgent. Her fingers slipped between her Faster and faster, she found her love button and pleasured herself.

The feeling of her sweat-drenched body, slick with desire, was unlike anything she had ever experienced before. Sarah reveled in the sensation of her own flesh, the heat and friction of her movements driving her to new heights of arousal. She was lost in a world of pure sensation, her body a vessel for pleasure and desire. As she worked herself into a frenzy, her breaths came in short gasps, her heart pounding in her chest.
With each stroke, she felt herself edging closer and closer to the brink of ecstasy. Finally, with a sharp intake of breath, she tumbled over the edge. She released like a cataclysm her muscles tensing and releasing in a powerful wave of pleasure. The bed shook like a storm but she gritted her teeth shut so Mark wouldn’t hear her. But her power shook the bed with too much abandon.
“Everything all right in there,” he yelled.

“Just fine,” she cooed. Better than fine.

K+++++

This is a very good start.. Wish to continue
K+

Hope for more +k

The clang of the gym locker door echoed through the near-empty room as Sarah slammed it shut. Sweat beaded on her forehead. Somehow, Sarah had found the energy to increase her training. Her goal wasn't just strength; it was a complete transformation. She wanted a physique that would set him in his place.

Day in and day out, Sarah reveled in her growth like a child unwrapping a long-awaited present. Mark, for his part, remained blissfully unaware, his world still revolving around the TV remote. But sometimes, when Sarah walked by in her new, muscle-bound form, he'd swear he saw a flicker of something in her eyes.

Finally, the day arrived. She had wanted to become twice as strong as Mark. It was a feat that he had to respect. He’d have to listen to her rather than just tell her what to do. Today, the squat rack had yielded to a staggering 600 pounds, and the bench press had groaned under the relentless assault of 300-pound reps. A triumphant grin stretched across her face – In her mind, it wasn't just weight; it was a declaration of dominance

Months of relentless training and her determination were part of it. The clandestine steroid regimen orchestrated by Cord was the rest. Both she and Cord knew that she was the stronger of the two of them now too. She was the one that everyone now looked to in the gym. She heard the whispers - “steroids,” “gear queen,” “massive,” but she didn’t care. She loved being noticed and was almost befuddled that Mark didn’t get the message.

That day she’d started with the biggest cocktail of gear ever. Cord was treating her like a guinea pig pushing the boundaries and still no side effects manifested. “I know you’re stronger than me now,” he chuckled. “I’ve seen you lifting. But now it looks like you’re bigger too. It’s almost impossible.”

She flexed her quadriceps, and a satisfied grin stretched across her face. Beneath the tight skin, the muscles pulsed with a life of their own, resembling sculpted mounds of granite carved by a master sculptor. The sweep of her hamstrings and the sinewy lines could be seen even through the fabric of her tights.

"My God," Cord breathed out, his voice laced with awe and a hint of something else. "Your legs, your glutes… everything. You're thick, striated… It’s been less than a year. I don’t know how this is physically possible.”

A slow smile played on Sarah’s lips. She pulled down her pants and made the muscles of her glutes dance. Beneath the taut, sun-kissed skin, the individual muscles rippled and pulsed with a life of their own. Each separate gluteus maximus seemed to fight for dominance, rolling and swaying with pinpoint control. Striations became prominent and then rolled away in vast waves.

Cord’s eyes widened. A flicker of something primal stirred within him.

Sarah quickly ended his reverie. “Stop staring and get on with it. I have a big workout ahead. It’s leg day and I need all the help I can get.”

"I don't think it works… well maybe with you it does work that way," he chuckled nervously, averting his gaze. "Anyway, I'm going to have to switch to the steel needles. The regular ones keep breaking now."

“I don’t care if it’s a firehose she laughed. Just put the juice inside me she commanded.”

"This might sting a bit."

Sarah scoffed. "Give me your worst. You know by now I can take the pain."
 
Cord’s hands trembled slightly as he filled each of the three vials to the brim. He cleaned the area with a practiced swipe and jabbed at her glutes with force.

Each time the plunger met resistance. With the second injection he pressed with such force that she bled a little. ​​The prick of the needle was almost insignificant compared to the waves of power that had already begun washing over her. Fire soon simmered beneath her skin. The feeling soon spread outwards like ripples on a pond, igniting a fire where it touched. Each muscle fiber, already buzzing with anticipation, seemed to welcome the intrusion, absorbing the liquid like a thirsty sponge.

Cord's breath hitched in his throat as his gaze followed the movement of her hand.

Soon enough it was painting her entire body with a flush of heat. A guttural sigh escaped her lips, a mixture of release and something deeper, a primal satisfaction that resonated from the core of her being. As always, Cord watched as the calloused palms of her hands caressed her body as the liquid hit her bloodstream. He now understood with Sarah the touch was a reflex. It was like an attempt to anchor herself amidst the rising tide of heat and power, but the effect was undeniably sensual.

Her fingers traced the path of the liquid fire. They followed the invisible map of veins that snaked across her form sending shivers cascading down her spine until her palms raked against her hot nipples. The touch was a delicious shock. Raw desire momentarily crashed through her body and the hardened points strained against the thin fabric. But the moment was fleeting. The heat, was soon replaced by a lingering warmth that settled over her like a comforting blanket. With a deep sigh, Sarah lowered her hands and Cord prepared the next injection.

He swallowed hard and grunted with effort on the final one. It was like the muscles were pushing back, affronted by the effort to be penetrated, even by such a small needle.

"There you go," Cord finally managed, his voice hoarse. "That should do it for today."

Sarah barely heard him. Her gaze was fixed on the reflection in the grimy gym mirror. The woman staring back was a stranger. She flexed again, watching the vast canvas of her glutes ripple and contract like a living map of veins and sinew. She would make it bigger still. That was the day she eclipsed her maxes which she assumed were more than twice the possible of her husband.

With powerful strides, she left the gym, the weight of her secret change a thrilling burden - both literally and hypothetically. Tonight she’d unveil the change with a calculated reveal, a silent declaration of her newfound dominance. But how?

great work

  Very exciting read.

Not sure if I'm going to finish - I really wasn't going to as I dropped it from the anthology. Let me know if you have any thoughts on directions and I might finish it.
----

The steam billowed from the bathroom muffling the sound of the shower but the door was cracked. Mark paced outside. He’d seen glimpses of Sarah’s newfound strength and it piqued his curiosity and in some ways threatened his manhood. He’d watched the effortless way she hoisted groceries and the casual twist of a jar lid that left him struggling. But tonight, something about the raw intensity in her voice as she declared her desire for change had unsettled him.

He peeked through the ajar bathroom door and saw her form behind the blurred glass. The sight left him spellbound, almost stumbling in disbelief. Sarah’s back was toward him. Through the blurred barrier, her back resembled a work of art. The gentle curves of her shoulder had given way to wide-defined deltoids. It flowed perfectly into the wide V-shaped slope of her back that was riveted with bulges and sinews that created a map of muscle. Tracing the line of her spine, the subtle ridges of her erector muscles bulged forth. As she moved, the muscles rippled and flexed. Veins like firehoses coursed beneath the surface
A pang of something akin to desire, laced with a healthy dose of fear, twisted in his gut. He needed to see for himself, to test the limits of this new Sarah. Ignoring the voice of reason, he barged into the bathroom just as the water turned off.

Sarah startled, turning to face him, water cascading down her impressive physique. The towel she held aloft barely concealed the sheer power etched into her form. Mark, caught off guard, felt a primal fear flicker in his eyes.

“What are you doing?” she asked in a calm but firm voice.

Shame washed over him. "I... I just wanted to see," he stammered. “You’re so big…” Needing to prove something, even to himself, he blurted out, "Let's arm wrestle."

Sarah raised an eyebrow and a hint of amusement played on her lips. Then, a slow smile spread across her face. She stepped out of the shower, the towel strategically draped around her. “Are you sure you want to know the results?”

Oh, you CAN’T stop now!  You just got to the good part!  You gotta show that Sarah overestimated how strong Mark is and the strength difference between Themis much greater than she thought it was! 

Please continue.