It was midnight of the third day of the two siblings state of continual bliss. He was on his back deep in thought as he doggie-cranked his little sister. He held her shoulders and crunched into her stretched and bruised pussy from behind as he considered what their mother had told him that morning. He felt his sisters tears on his cheast as he remembered waking to find she had delivered a very tiny baby girl and was deperately trying to care for it. Her tiny breasts ached to be suckled but they were too undeveloped to give more than a squirt of milk. Their mother entered just then. Seeing the baby she ripped open her blouse. Her breasts were huge, her nipples were swollen and dripping milk. It was as if she were a new mother too.
The memory of his mothers ample bosom made him forget his control and he began a long-grinding orgasm in his sister....as he raptured in her he recalled the morning.
He was sitting with his mother as she fed his child and sis went for a bowl of cereal. "Mom, how can you give milk? Why are your boobs so big all of a sudden?"
She smiled looking at her granddaughter, "Your seed grows babies fast. The first time you gave some to your sister, I took some for myself. I gave birth to your second sister/daughter yesterday."
He stared at her unbelieving.
"Oh come now," she continued "It's not the first time. Think. Your 'sister' is six years old. You are seventeen. Your father left when you were four."
He looked confused.
"When you were young you would climb in bed with me. One night, you must have had a young man's dream. You were on me and inside me. Because you were so young you only bloodied me some, but it was so wonderful to feel that power of your father tearing at me, I was willing to die a horrible death for your cock in me"...
As he recalled her words, he slapped loudly against his sisters ass with the long strokes of his hips plunging her vagina as she cried for release...
"In the end, I survived the..rape" she winked wickedly at him "and gave birth to your 'sister'. You didn't remember the next day, or at least you didn't seem to remember."
His heart leapt.
How wonderful!
How confusing?
"But for now, I will care for your newborns so you can care for your lover...." He leaned down to her and suckled milk from her unoccupied breast while she stroked a handful of cum from him. She applied some to her nipple, let the baby feed from it and licked up the rest herself...
He had quickened his pace in sis and he had swollen again. Blood splattered from her with each thrust and now she was clenching in climax. Her renewed pussy tightened on him bringing him to instant orgasm. He groaned loud and low and she yelped with spasms of pleasure. They both passed out in a puddle of semen, blood and pussy juice