Amy's Step Sister #3

Note : This story is completely fictional!

The weekend passed and Amy was staying over with a friend. She couldn't wait to get back to see her sister, though. When she got back home Monday, her parents stayed up late watching movies, and she couldn't get to her sister's room. Tuesday morning finally came. When Amy got up it was 10:30. She only had to wait an hour and a half for Kaitlyn to get home. She decided to watch some TV. After several game shows, Kaitlyn came home. "Hi Kait. Did you remember the stuff you were going to get?" Amy asked. "I did,” Kaitlyn replied “ and I have a little surprise for you too. You wait in here until I'm ready." Kaitlyn went into the kitchen. Amy wondered what the surprise was. She was wearing a mini-dress, with white panties with little purple flowers on them. She was wondering if she should undress when her sister called through the swinging doors of the kitchen.

"Amy Bates." Kaitlyn was still in her candy-striper outfit. She held a clipboard in one hand. Amy went to the kitchen. "Right this way miss Bates." She ushered her little sister into the kitchen. The kitchen had a center counter. mom had said that she worked better in a kitchen with this kind of counter. Kaitlyn had cleaned the counter off and laid down white paper over the top of it so that it looked like an exam table. 'Nurse' Kaitlyn lifted her patient onto the 'exam table'. "Miss Bates," she said, trying to sound authoritative, "I need to take your temperature rectally. Please remove your panties."

Amy felt a thrill run down her back. This was kind of neat and kind of scary and made her really horny all at once. She pulled up her skirt and slipped her panties down her creamy legs and off. In the bright kitchen light, her red pubic fuzz almost glowed.

"Please lay back and hold each leg under the knee with your arms." For and 18 year old, Amy was still very limber and actually lay back with a leg tucked completely under each arm. Her young, round, white bottom now stuck lewdly up into the air. "Very good, Miss Bates." Without further warning, Kaitlyn slid the cold probe into her sister's tiny ass pucker. Amy moaned pretty loudly this time, not concerned about anyone hearing, since her parents would not be home for another 4 hours.

Kaitlyn stared at the lewdness of the sight. Her sister with her butt in the air and a thermometer stuck out of it. She had thought today's 'play-time' would be disgusting, but instead she felt a strange desire building in her, one she had not felt before. She stayed in her role for now, though. She pulled out the thermometer. It was completely clean except for the small amount of KY she had applied to it. She pretended to have read it as she wiped it off. "Hmmm. Miss Bates, I'm not sure what these readings mean. I'm afraid I'll have to give you a rectal exam to find out.

Amy had heard her sister use those words before. She almost came just thinking about 'Nurse' Kaitlyn probing her bottom with her finger. She heard her sister snap on the surgical glove. Kaitlyn squirted KY onto the index finger of the glove. She walked over to her sisters young, round ass, presented totally vulnerable for her. She had a sense of power. She knew her sister wanted her to plunge into her tiny asshole with her finger. She placed her well-lubed, gloved finger over the opening.

Amy felt a sudden rush of feelings from her bottom-hole. She felt full and tingly and wonderful. Kaitlyn shoved the finger in hard, all the way in. Amy began to moan constantly, unable to speak or even think about anything but the sensations inside her bottom.

Kaitlyn had lost any hope of keeping enough composure to keep up the 'Nurse' role. She swirled her finger delicately inside her sister's butt. She twisted it and pulled it out. Then wiggled it as she slid it back in. The hole seemed to loosen up some, and Kaitlyn wondered briefly if she should try another finger. She decided to wait till later.

Amy's little bottom-hole felt hungry. She loved the sensations. Kaitlyn's finger plunged in again, deeper than ever before. The pressure sent her spinning over the edge of orgasm. Wave after wave hit her like a typhoon battering a beach. Finally her climax subsided. Kaitlyn removed her finger slowly; lust glazing her eyes after seeing Amy's intense orgasm. Amy let her legs drop back down finally. "Thank you sis. That was better than I had ever imagined. If these keep getting better, I may not be able to stand it." She said. "You will, little sister. You will." Kaitlyn said, her desire building. "Let's clean this stuff up and go upstairs."