Can brother help asexual running sister?

NB; The following story has themes of incest and is purely for entertainment only.

Enjoy reading..

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My little sister is a runner. A very good runner. At 25 Karen was supported by a major shoe company to represent them. At 5'7" she had the perfect runner's body. Obviously slender, she carried at most 110 pounds on long, shapely legs. Light brown hair. Very fine and kept short. Round face with regular features but deep, deep blue eyes that see the world as competition. She was at the starting line and was going to kick the world's ass. She wouldn't be using her tits...