Emily couldn't believe she was saying this. "A woman."
Rick didn't believe her, and came up to see for himself. Sure enough, the photo showed someone in the same pose he'd been making, who looked a lot like him, but... it was a woman. She looked so like him she could be his twin sister, but she was irrefutably a woman, wearing a cute sundress no less.
As he touched the photo, he felt strange. Before his eyes, his clothes seemed to vanish and everything went blurry- not only the world, but his memories, his perception of himself. Everything felt off- in some places he seemed to be contracting, in others expanding. Between his legs he felt weirdly empty, and at his chest he felt oddly full. His brain seemed to be rewriting itself, memories and even instincts adjusting and the old versions feeling like dreams.
The blurriness around his body faded, and he watched as it started to change. His hips and thighs widened out as his shoulders narrowed. Mammaries inside him connected to his nipples, and they swelled as new flesh accumulated on his chest. His penis shrank away rapidly, the protrusion between his legs vanishing before his eyes. The testicles connected to it moved inside the body and transformed, the genetic information of the sperm they had contained reconstituting to serve the opposite reproductive function. His scrotum became almost flush with his crotch, and the seam at its centre peeled open as it separated into labial lips around a vaginal passage.
Something finally came that made all of this feel totally right- her name. Rosa. Memories of her life as a girl slid naturally into place in her head now, as did seeing herself as a woman, right down to going by 'she' rather than 'he'. And around her body Rosa's cute sundress from the picture appeared on her, as did her underwear. The blur of time finally stopped and she saw Emily looking at her again.