The creature grinned to hirself as sie quickly reached the house at the edge of the woods. Jim's memories told hir that not only that Jim's girlfriend lived here alone, but that she was likely already asleep in bed. Sie purred quietly, hir large black barbed member poking out in anticipation even as sie took the spare key from its hiding place and silently opened the door. Sie crept indoors, silently making hir way towards the bedroom where hir girlfriend slept.
Jen had slept fitfully that evening. She'd been more annoyed than concerned when Jim hadn't shown up to visit her as he'd promised he would. She'd waited for him until fatigue overtook her, and had finally given up and gone to bed. Her dreams so far had been of Jim, but were far darker than usual.
What finally startled Jen awake was not the feeling of weight upon her, but rather the sensation of something sharp pinning her arms and legs to the bed. She opened her eyes and let out a gasp as she saw the glowing purple eyes of what used to be Jim staring down at her. The creature grinned to her, showing far too many teeth, and then purred in a deep voice, "Hi Jen, I've brought something for you. I hope you like it as much as I do."
Jen went to scream, but was quickly silenced as the maw of the creature covered her mouth in a kiss. She felt pain shoot through her body as the monster plunged its barbed organ into her sex, stretching her tight and scraping her insides with those sharp protrusions. And the pain seemed only to worsen with each stroke, until suddenly a strange tingling, and then mind-blowing pleasure overtook it as the creature's night-black pre leaked out and corrupted her walls. Her eyes rolled back with the sensation even as the creature purred to her, "Mmmm, feels good, doesn't it? Don't worry...there's more where that came from." Sie stroked with increasing speed and then buried hirself in Jen's sex, flooding her with black, corrupted seed.
Jen's eyes went wide open as pleasure unlike any she'd ever felt swept through her body as the creature's influence spread. Her whole body shook as the corrupting black fluid spread throughout it before flooding out from every pore. She gasped, feeling her body bulge with new muscles, even as it grew far curvier. Her arms and legs twitched even as they altered, huge talons erupting from fingers and toes, legs and feet stretching into the same digitigrade ones of the creature on top of her. Her new long tail twitched in anticipation as her modest breasts swelled to a size equal to the ones of the thing on top of her. Her face stretched outward into a muzzle while six horns crew out from her head and her eyes took on the same shade of purple as the ones staring down at her. Her new wings, she found, were pinned uncomfortably under her body.
That which used to be Jim smiled darkly as hir girlfriend's body shook in the throes of her change. Sie grinned, reaching down to stroke at Jen's new male sheath and sac as they formed and sie purred as an organ as large as hir own peeked out. Jen panted as hir mind gave way to the inflowing darkness, and sie looked up at Jim now with lust not fear in hir eyes. What used to be Jen purred at the sensation as hir womb swelled with eggs, ready to unleash more of their kind upon the world.