The Endurance Test

Lilly's pleasure crested and crashed. She tried to cut her scream short, as her pelvic muscles spasmed and contracted. Practice, she mused to herself, for the contractions to come.

Brian felt his sister cumming around him, and couldn't contain himself any longer. He felt all of his built up fluid rushing out of him, into her. The original sin that had maybe damned them forever. He felt her vaginal walls pressing in on him, squeezing it out of him, still hungry for it even after the spark of life had already been lit deep inside her. She collapsed on top of him, shaking with the echoes of her climax.

Eventually they regained their senses, and Lilly got up off him. Again, Brian knew how much he had just ejaculated inside her, but none of it seeped out of her, as she started getting dressed. Maybe they could get away with fucking bareback, so long as the evidence all stayed hidden inside her. But now they knew it wasn't safe, despite her taking the pill. Except that with her already pregnant, the damage was already done, for as long as she was in that state--either until she ended the pregnancy or until the baby was born. It left Brian with a conflicting mess of desires.

"Were you serious about keeping it, or was that just...?" he asked.

"I dunno," she said with a wink. "We'll see, I guess."