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! 

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.
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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?”