((Fine by me. Just PM it to me, or link it in your response.^_^ The sister's name is Sarah. And their family name is Bylere.))
"Oh..........dear brother.......you're so........good........." Mary Bylere moaned out lustfully as she sat atop her brother in bed, grinding her hips furiously on his manhood. Head tossed back, moaning up into the air, with her exceptionally large and perky breasts on great display, bouncing as she rid him. The twenty two year old was a beauty like few others. Fiery red hair, gorgeous face, deep, beautiful eyes, and a body of absolute perfection.
Her lover, was her very own younger brother, at the tender age of seventeen. This had been going on for a few years now. While he saw it as making love with his ideal woman, to her, this was just using him as a means to an end. While her father treated her with love, he also paid no thought to her ever taking over as head of their family, even before her brother was born. When he was born, their father doted all over him, grooming him to be king, while she was expected to just be a loyal sister and nothing more. Her ambitions were far grander than that. So, she had seduced her brother, using their closeness and her incredibly good looks, years earlier. He was a honorable young lad, but still a young man. He was powerless against her wiles. She hadn't expected their father to die so soon, but was actually happy about it, cause it meant she could accomplish her political ambitions all the sooner.
So now, while he stood as head of the house of Bylere, she was the one who really ruled it, manipulating every decision he made to her liking.