Jane/Janith had overlooked something important when she had a family: she never considered what might happen to her children when their mother was a succubus.
Her oldest daughter, Jill, had lead a seemingly normal life for her first seventeen years. Sure, she had a bit of a temper, but she was a redhead and everyone just assumed it was the typical fiery redhead stereotype. There was far more to it than one realized yet. Jill had dated several boys, but nothing serious or intimate yet. Now in her senior year of high school, she went to bed looking forward to the next day being her 18th birthday.
That night, she had strange and erotic dreams like she had never had before. The dreams culminated with one where she went to her boyfriend's house, initiated sex with him, and fucked him to death. The in-dream orgasm jolted Jill awake. She found herself breathing deeply, drenched in sweat, and - by the feeling between her legs - the orgasm was real. She threw back her sheets to find she had also stripped off her pajamas in her sleep. What the hell?
Jill rolled out of bed and stood up on unsteady feet. She braced herself against the bedpost as a sensation of warmth swept over her. Were her breasts bigger? That was impossible. She cupped her breasts and realized they were unmistakably bigger than before. Was she hallucinating? Jill felt her forehead and found she seemed to be burning up. Her head was beginning to throb. That had to be it: a severe fever causing hallucinations. Better get some Advil immediately. She took a few steps toward her bedroom door and found here feet were now aching. Then remembered she was naked. She turned around to get her pajamas and was hit by a full body spasm. Jill clutched the bedpost to avoid falling over. Steadying herself, she became strangely intrigued by the bedpost. She ran her hands up and down the wood, feeling its curves and patterns. It reminded her of something she needed...
She shook her head. "No!" she though to herself. "This is not how I want to spend my 18th birthday!" She stamped her foot in frustration, but the sound it made against the floor didn't sound right. Jill looked down to find her feet were changing color and shape. They looked like...black hooves? The pressure was building in her head now, like it was going to explode. Jill put her hands on her temples as if to hold her skull together only to feel something...two somethings...pushing out of her forehead just below her hairline. She felt the growths, felt them slowly extended outward until the pressure in her head finally eased off. It was like she had grown a pair of horns! Her back began to spasm then she felt something break free from the area around her shoulder blades. Spasms travelled down her back to her tailbone where she felt an impossible stretching feeling. She reached back to find a fleshy tail slowly extending from her tailbone.
Confused and afraid, Jill staggered toward the mirror in her room, unsteady on her new feet. Sure enough, her reflection showed horns on her head and leathery wings on her back. She had turned into some kind of demoness. The burning sensation was finally leaving her body...mostly. One part of her still burned...yearned...needed. She felt a hunger, a need to feed...on a man. Yes, that was it.
That craving brought another word to Jill's mind that more accurately described her change: not just a demoness, but a succubus.