You need it

You twist on the couch, throwing one leg in the air so you can reach your aching pussy. Your fingers find your opening, shaved bare and slick with yearning. You stroke, sating the deep itch the Stranger has made to burn within you. Biting your lip and running your hand through silky hair you twist and writhe, fingering yourself harder, faster, circling your little clit until the first beautiful orgasm escapes, burning through you and driving a moan from your lips.
Your brother watches you, frozen by the Stranger's spell as you enjoy his girlfriend's body. Twisting and turning you sink your fingers deeper into your pussy. Fuck, you're so wet now, the squelching of your fingers alone enough to bring you to climax once more. You can't help yourself. Your body feels amazing and you continue stroking greedily, running your hands down the new contours of your face, across those soft brows, following the delicate slip of your nose, the lips you've longed to kiss, down your slender neck, to your firm little tits.
You're stuck as Katie, forced to finger yourself for the Stranger's amusement. You've always had sort of a crush on her, been jealous of your brother. And now you feel guilty for enjoying your stolen body so eagerly, even if it's not within your power to stop.
You cum for a third time, voice crying out in lust, eyes clenched shut as your entire body vibrates with orgasm.
"That's enough," the Stranger says, freeing you from the spell.
Your fingers come out of yourself and you lie helpless on the couch.
"Let your brother show you how to work that body," the Stranger orders.

A man’s mind gets stuck in the body of his alluring coworker and he slowly gains control, changing her life to fit his desires in Out of His Mind, available on Smashwords and Amazon. Preview here.