Batman and robin

Amy and Gwen stood in their separate boxes, the clear panels sealing shut with a soft hiss. For a second there was only the sound of their own breathing. Then a fine blue mist began to seep in from the vents near the floor. It rose quickly, cool and faintly sweet-smelling, curling around their ankles, then their thighs, then higher. Amy’s first instinct was to hold her breath. Gwen tried the same. It didn’t last. The gas was dense and insistent; within moments both of them had to inhale.

It filled their lungs in a single deep pull. The effect was immediate and strange a spreading warmth that started in their chests and radiated outward, loosening every muscle and joint. Amy’s fingers twitched against the glass. Gwen’s knees nearly buckled. The blue fog thickened until they could barely see each other through the haze, but they could hear the soft, involuntary sounds each of them made as the change began.

Amy felt it first in her shoulders and arms. Muscle swelled under the skin in slow, rolling waves. Her biceps thickened, her forearms grew heavier, veins rising along the surface as her frame broadened. The same thing was happening to Gwen; through the fog Amy could make out the way Gwen’s once-slender arms were filling out, deltoids rounding, chest expanding as her ribcage widened. Both of them were getting taller by inches, their stances shifting as their centers of gravity dropped and their legs took on new mass thighs thickening, calves hardening into defined muscle.

Their breasts were next. Amy felt a deep, pulling tightness as the soft weight of them began to recede. The tissue flattened and firmed, the skin smoothing until her chest was broad and flat, only the faint outline of pectorals remaining. Gwen made a startled sound as the same thing happened to her; the cups of her top went slack, then empty, as her chest reshaped into something hard and masculine. At the same time their hips narrowed and their asses tightened and shrank, the curves of their lower bodies pulling in until they had the lean, powerful lines of male athletes. Every part of them was rewriting itself jawlines sharpening, cheekbones rising, voices dropping into lower registers even as they gasped. By the time the worst of the reshaping finished, both of them were staring down at bodies that were unmistakably male: tall, heavily muscled, and strikingly handsome, with strong features that still somehow carried a faint echo of who they’d been.

The final change came last and hit them both at once. A low, aching heat gathered between their legs. Amy’s breath caught as she felt her pussy begin to change lips thinning, the opening drawing upward and inward while new flesh pushed outward from the base. A cock grew from her in a slow, steady surge, lengthening and thickening as it formed, the shaft heavy and sensitive. Beneath it, her balls descended and filled, the weight of them settling into a new scrotum that felt foreign and electric. Gwen was going through the exact same thing; Amy could hear her sharp, broken inhale as the same growth happened to her. Within moments both of them were fully male cocks half-hard from the raw sensitivity of the change, balls hanging heavy, every trace of their former bodies gone.

The gas thinned and the panels unlocked. As the doors swung open, two folded costumes dropped from slots above them. Amy’s was the full black and gray Batman suit, cowl and cape included. Gwen’s was the red and green Robin costume, complete with the short cape and utility belt. They stood there for a second, still catching their breath, staring down at the unfamiliar weight and shape of their new bodies while the costumes waited at their feet. Neither of them spoke. The strength hummed under their skin. The constant, low throb of their new cocks was impossible to ignore. And somewhere outside the boxes, the convention floor was already full of beautiful women in tight costumes women their newly male bodies were already reacting to in ways neither of them had ever felt before.