Sleeping against a soft female form he nudged his hard cock towards her buttocks. It was an unconscious act, something most brothers and sisters know about when they come of age. For that very reason their mother had protested when they said that they were willing to share his bed as there were guests in the house and space was limited.
Mild surprise had registered in their eyes when she had made subtle indications for they had always slept together since they were children and that too naked.
There had never been sexual overtures between the two despite the close proximity as they belonged to a nudist family. They had often seen their parents nude around the house and thought nothing of it.
But now spooned against his form she felt his hard ridge poke her. It was as if someone was pushing a big hard rod into her butt crack. She knew he was asleep as his breathing was slow and even.
Her breathing became shallow as she felt his hand slowly move from her waist to her breast. The nipple rose to meet his fingers through the thin night shirt. Desire began to curl around her clit lips and she massaged her pussy very gently as she didn't want him to pull away.
With his hand resting on her breast he snuggled his head against her nape. His breathing fanned her hair and made her shiver. Blood was rushing through her body and she wanted to grab his hard cock and pull it into her mouth. Wriggling her butt against his dick she gave it access by lifting her night shirt and curling her leg slightly inwards into her chest. He moved closer and she felt his prick at the edge of her arsehole.
She closed her eyes at the sensations that invaded her body and clamored for satisfaction. Rubbing her clit she willed an orgasm but she knew that masturbation was not the answer. She wanted to feel her twin brother's prick pulse in her pussy hard and to drive her to the peak of passion again and again. But she also knew that if he woke up the spell would break and he would move away affronted.