Carrie ran up to a small field of flowers, with bees happily going about their business and birds playing in the light breeze. A moment later, John caught up to her, panting slightly. Carrie was absorbed in watching the play of the birds, but John was more taken with the beauty of the plants around him. The flowers were so very bright, the small bushes were perfectly-shaped, and there was a light aroma in the air.
John picked a flower, and took a deep smell. Carrie put her hand out and watched as a robin landed perfectly. Carrie began to sing to the bird, and the bird sang back beautifully. They were both content.
Dr Jackal was just finished setting up his experiment. He had been fascinated with lasers as a kid almost as much as he was with chemicals and potions. His newest invention would revolutionise the cooking of cauliflower. But he had to test it. He turned to press the big red "POWER" button, but bumped the alignment controls as he hit it. The laser swung to the left, before firing.
"Oh dear, oh dear, I hope I didn't cause any trouble... Oh well, I'd best take my potion." The Doctor just couldn't help it, he was addicted to that blasted potion.
Suddenly, out of Nowhere, a laser shot through the air, hitting first John, then Carrie. The entire area started to glow.
As Carrie was hit, her singing changed. Her voice went up a number of octaves. Then her entire body started to sprout feathers, and then her arse began to rapidly grow backwards, tearing her underwear and her dress. The robin sprang from her hand and started flying around her.
Meanwhile, John found that he was unable to lift his legs. He was rooted to the spot (literally). Looking down, he watched as his shoes were engulfed by thick brown roots growing from his legs. He tried to scream, only to find that he wasn't even breathing.
Carrie screamed as her arms were pulled back and her chest exploded out, destroying her blouse, but it came out as more of a tweeting. She felt her legs changing, and looked down to see her big toes twisting to face backwards, and her legs becoming thin and dark. Her hands were melted into her arms, which changed shape and settled on her back, now fully-formed wings.
John gaped as his legs fused together, and shuddered as his manhood hardened, then began to grow rapidly, his clothes disintegrating. He watched as smaller branches grew off his now two-foot-long penis, the end tapering to a point.
Carrie's chirps grew more frantic as her mouth reformed into a beak, and she began to shrink. Glancing back, she saw John, now half-tree.
John struggled as his torso rounded and turned to wood, and suddenly felt the urge to raise his hands. As he did so, his fingers and the branches of his once-penis sprouted leaves, and more branches formed off his arms and torso. Moments later, all that was left of his old body was his head.
Carrie looked at John, then glanced at the robin. Suddenly, she noticed the robin was male. As the last vestiges of humanity faded from Carrie's body, she launched herself into the air, still somewhat large, but just capable of carrying her own weight. The robin chirped excitedly.
John tried one last time to scream, and his tongue shot out of his mouth, branches forming off it as it grew. More branches grew from his head, and suddenly his entire body was wooden. More leaves grew from John's branches, and then he focused, and gorgeous flowers bloomed from his buds.
Carrie's body became just slightly smaller than the male robin's, and she flew up to land in John's branches. The male robin followed, and began to woo her, cooing softly and displaying his beautiful feathers.