I interned last summer at a law firm in the city. I stayed at my stepsister Sara's apartment. We got on well enough, and she spent most nights at her boyfriend's place so I had the apartment to myself much of the time. As it happens I would have welcomed more of her company because it's one of those towns where everyone heads back to the suburbs at five-thirty. Some nights I went out to a bar with some guys from work, but apart from that I didn't have much of a social life. And I hadn't had sex since breaking up with my girlfriend a couple of months before.



So most nights I watched television or played around on the computer. In truth I was bored, which was why I wandered into Sara's bedroom one night to look around. I wasn't searching for anything in particular, but in a drawer next to the bed I found a dildo and lubricant and a pair of handcuffs. Sara is very pretty, but to me she had always seemed a little straight-laced, and it was hard to picture her using that dildo. But once that picture had formed in my mind I started to get horny. And then I found her underwear drawer and that confirmed that there was more to her than met the eye. I lingered over her collection of sexy panties trying to find her scent. I took some pretty white boy shorts back to my room and masturbated while holding them against my cock, being careful not to get my cum on them.



After that first time, I went back to her bedroom every night I knew she would be out. Soon, just rubbing her underwear against my cock wasn't enough, and one night I slipped on a pair of her black panties and watched myself in the mirror next to her bed as I masturbated. The sight of her panties tight against my cock excited me so much that I got cum all over them them and had to scramble to clean and dry them that night. The next night I shaved off the hair around my cock and balls and the sight of her panties against my bare skin turned me on even more. And I started to explore her other clothes and experiment with her make-up. I spent hours in her room dressing and making myself up, then lounging on her bed with my skirt hiked up and my panties pulled down watching myself in her mirror as I played with my cock. And that is how Dan, Sara's boyfriend, found me one night as he walked into her bedroom.



I froze in shock, my hand still holding my cock. Dan looked shocked too. Neither of us spoke. Then we both spoke at once. "Sorry," we said at the same time.



Dan regained his composure quicker than me. "I didn't mean to surprise you," he said. "I let myself in and saw the light in Sara's room and thought she was home already."



"She's coming home?" I stammered. "I thought she was going to be at your place."



"She had to work late so she called me to tell me to meet her here," he said.



"Oh god," I said. "She'll kill me if she finds me here."



"You've got a few minutes to change," Dan said. "But you'd better hurry."



He left the room and I quickly undressed. I hurriedly put her clothes back in the wardrobe and drawers and smoothed down the bed cover. I checked her make-up to be sure that I hadn't spilled anything. I didn't remove the make-up from my face; I could do that when I got back to my room, if I managed to get that far.



But then I realized that I didn't have my own clothes with me; I had undressed in my room before going to Sara's bedroom, so I was going to have to walk out of her room and walk past Dan to my room wearing only my make-up. I stood by the bedroom door plucking up courage. I had no choice. I opened the door and walked out. Dan was sitting on the couch facing me. He watched as I walked towards him as nonchalantly as I could with a hard cock. I couldn't meet his eyes. I hurried past him and felt his gaze on my ass, but let out my breath with a sigh of relief as I reached for the door of my room. But then he spoke. "You've forgotten something." I turned to look at him. He was pointing to my ankle. Sara's ankle bracelet.



"Just take it off," Dan said, standing up and walking towards me. "I'll put it back in her room."



"Yes, thanks," I muttered, and bent down to take it off, but in my panic my fingers fumbled with the clasp, and as I fumbled I realized that I had turned my back to Dan giving him a close-up view of my ass, which made me fumble even more. "Let me do it," Dan said, and kneeled down to help me. "No, I can manage," I blurted out as I saw his face level with my cock. At last I managed to free the clasp. I stood up, handed him the bracelet, and rushed to my room. I showered, removed my make-up, and fell on my bed, almost weeping with the humiliation. Dan will tell her, I thought, and she'll tell my parents, and everyone will know, and I'll be ruined!



I stayed in my room listening for Sara's key in the door. She arrived about five minutes later. "Hi bro!," she shouted out, as always. "Hi sis," I shouted back with less enthusiasm. I waited, and waited some more, for the inevitable explosion. But none came. So after a while I got off the bed and left the room. Dan was sitting on the couch and I heard the shower running in Sara's room.



"Did you tell her?" I asked.



"No. Did you think I would?"



"I don't know," I said. "I mean, it's not everyday you find your girlfriend's brother wearing her clothes."



"And playing with his cock," Dan added, smiling at me. "Don't forget that."



"No," I said, "I'm not likely to."



Sara called from her room. "I'll be out in a minute."



"Ok," Dan called back. "We're going for dinner, " he said to me, "but we'll be back later. So maybe you shouldn't go back to her room when we leave."



"No chance," I said. "I couldn't stand another shock like that."



Dan smiled again, and was about to say something, but Sara came out of her room.



"See you soon," she said.



"Ok, have fun," I said. I went back to my room and lay on the bed. How many times in recent weeks had I imagined someone standing watching me as I masturbated, my panties pulled down to my thighs? How many times in recent weeks had I described this fantasy in texts and even telephone conversations with anonymous guys as they told me how they wanted to put me on my knees and pull down my panties and fuck me? My body quivered in excitement and humiliation and I came as I pictured Dan kneeling to help me with the clasp, but this time his face moving closer and closer to my cock. I woke up at the sound of Dan and Sara coming home and lay awake listening to my sister's muffled moans. I imagined her on her knees cuffed to the bed as Dan's cock slid in and out of her pussy. I played with my cock again as I pictured myself taking her place.



I woke up the next morning as Sara left for her Saturday morning dance class. I got out of bed, showered, and walked out into the kitchen. Dan was sitting at the table drinking coffee and reading the newspaper. "Want coffee?" he asked. "Yes," I said. I sat at the table and picked up a section of the newspaper. He poured me some coffee and handed it to me with an odd expression on his face.



"What?" I asked.



"I never saw your resemblance to Sara before. I guess the make-up made me see it."



"Really?" I said, genuinely surprised. "If I were anywhere near as pretty as her . . ." I saw where I was heading, and stopped.



"Then what?" he asked.



"I'd be more confident when I dress up," I said, quietly.



"What do you mean?"



I had said enough already. Dan noticed my reticence. "I didn't mean to pry," he said. "We can drop the subject."



"It's ok," I said. "It's just that I've never told anyone about this before. I meant that if I were more confident that I could get away with it then I might do more than hang out in the apartment when I'm dressed."



"So what else might you do?"



"Go out. You know, to a bar or something, to meet someone." So now I had confessed. Not just to dressing up as a girl and playing with my cock but to wanting to be with another guy.



Dan paused to take in what I had said. Then he said, "Sure you could get away with it. You looked so pretty last night. And you have a very feminine figure." I blushed, remembering again his eyes running over my body as I walked past him naked and hard. "And a great taste in underwear," he added. "I bought those panties for Sara."



"I'm sorry," I said.



"What for?" he asked, laughing. "They look just as good on you as they do on her." We were both silent for a couple of minutes, both pretending to read our sections of the newspaper. Then we looked up and caught each other's eyes and smiled.



"Would you do me a favor?" Dan asked.



"Tell me what it is," I said.



"Will you dress up again. For me?"



"You mean now?" I asked. "Here?"



"Yes. Sara won't be home for another couple of hours."



I sat there as though I were weighing how to answer, but in fact there was nothing to think about. "Yes," I said. "But it'll take a few minutes."



"I'll try to be patient," he said.



I got up from the table and walked to Sara's bedroom and closed the door behind me. I stood in front of the mirror and took off my t-shirt and jeans. Then I got to work. First the make-up; then the same panties as I had on last night and a matching black camisole; then a short black skirt and a cream-colored blouse; and finally the ankle bracelet. I stood in front of the mirror again and tucked my hair behind my ears. Can I really do this? I asked myself, then felt a familiar feeling in my cock and realized that I could and must.



I walked to the door, opened it, and stepped out. Dan watched me as I walked towards him. I stopped a few feet away. "Well?" I asked, nervously.



"You look so pretty," he said, "Turn around so I can see the full effect." I complied and again felt his gaze on my ass. I turned back toward him and he stood up and took two steps toward me. His hands went to hold my waist, but he paused and asked, "May I?"



"Yes," I replied, and he held my waist and pulled me gently toward him. He kissed me softly and I sighed as his lips brushed mine. His next kiss was firmer. I opened my lips to invite his tongue into my mouth. He kissed me deeply and pulled me closer to him and his hard cock pressed against me. His excitement made me even more excited. His hands were now on my ass, lifting my skirt, his fingers sliding into my panties, caressing and exploring me. He undid my skirt and let it fall to the floor and unbuttoned my blouse and slipped that off my shoulders. Then he took my hand and led me back to Sara's bedroom.



I stood in front of her mirror dressed only in her panties and camisole. Dan stood behind me; his hands slid under my camisole and he took my nipples in his fingers and gently pinched them. He kissed my neck. Then he undid his jeans and pulled them off. In the mirror I saw his hard cock. I had been imagining this moment for weeks and had no doubts about what I wanted. I knelt in front of him and and put my lips on his cock, then my tongue, and then took him into my mouth. He moaned loudly and with small movements he started pushing against my face, his hands on my head and his fingers in my hair. In the mirror I could see him gently fucking my mouth and I thought how it would look to an audience, and I imagined someone walking in and finding us like that and getting so excited watching us. Dan pulled his t-shirt over his head, and his nakedness made my cock strain harder against my panties. He fucked my mouth for long exquisite minutes. My confidence grew as my mouth and tongue caressed his cock and I got ready to to feel his cum shoot into my throat.



But Dan reached down and took my hands and helped me stand. He kissed me and his hands again went to my ass and pulled my panties down. My cock sprung out and touched his.



"Last night I wanted to put you over the couch and fuck you there and then," he said.



"And I imagined that you were fucking me as I heard you fucking Sara," I said.



He guided me to Sara's bed and placed me kneeling in front of the mirror. He took the lubricant from the bedside drawer and squeezed some on my ass and stood behind me. His hand guided his cock toward me. I felt his it against my opening, and then he pushed slowly into me. It felt so different from Sara's dildo; now, I wasn't in control of the movements. In the mirror I could see him thrusting against me, his hands grasping my ass, pulling out, pushing back in. I looked at myself, my panties pulled down around my thighs, my mouth making a wide O as I moaned with pleasure as his cock fucked my ass. My lipstick was smeared and my hair was no longer tucked behind my ears. My sluttiness turned me on yet more, as did the excitement on Dan's face as he fucked me. His thrusts got deeper and faster, rocking my body forward, then pulling it back for the next thrust. With each thrust his balls slapped against me. Then he came, forcing his cock deep into me, his hands gripping my ass hard and a loud long moan escaping from his mouth.



Gently now, Dan continued fucking me as his cock softened. Then he pulled out of me. I lay on my back looking at him standing in front of me. Then he knelt beside me on the bed, and took my cock in his hand and started to stroke me, his hand held tightly around my shaft squeezing the tip of my cock with each long slow stroke. He kissed me softly on the lips and I came, my cum spurting out over his hand.



We lay back on the bed, his arms around me, my head on his shoulders.



"Is that how you imagined it would be, being on your knees and being fucked?" he asked.



"Better than I imagined. It was incredible."



"Oh no!" he said. "So much pressure to make it as good the next time!"



I kissed him on the cheek. "So there will be a next time?"



"You think I could resist fucking your cute ass again?"



"So that's how you think of me? A girl with a cute ass?"



"No," he said, rolling me over and lying on top of me. "I think of you as a girl with a cute ass, pretty little nipples, and a very pretty mouth. Oh, and a beautiful cock."



"And my personality? That doesn't enter into it?"



"Of course it does. You have a wonderfully slutty personality."



I laughed and pushed him away. He stood up and helped me up off the bed. We stood together in front of the mirror looking at our reflection.



"So cute," he said, his hand caressing my ass. He kissed me again, and I went back to my room. I stood in the shower, hot water running down my body, my cock hard again as I remembered how his cock felt inside me.