As the months went on, my sister and I continued what I'd become accustomed to thinking of as our fuck sessions. Any reluctance that Rachel had shown was gone, and she had become the aggressor in our relationship.
Rachel became slowly but steadily more adventurous, wanting to try new things in new places. Her increasing depravity made her increasingly horny. She had me fuck her ass almost every time, and she would cum multiple times with my cock in her ass. When I would finally cum, spraying her bowels with a huge load of semen, she would scream as she came. These orgasms were so powerful that she passed out more often than not. Needless to say, these sessions took place with our parents nowhere near the house.
More frequently, she'd sneak into my room at night, usually when our parents were asleep, but she didn't always wait. We would go down on each other and fuck in every position in complete silence. She would leave my room covered in cum, relishing the risk of bumping into our parents with my cum dripping off her nipples and running down her belly.
I enjoyed the ride that we were on, and was eager to see what my sister had in store for us next. While every time we got together was amazing, a couple of times stood out from the rest.
*****
The most memorable encounter also turned out to be one of the shortest. Our parents had taken us out for dinner for our birthdays. We went to a 5-star restaurant in a luxury hotel in the city. We had been here many times, but not since my sister and I had started down our current path. After we had ordered, my sister excused herself and stood to go to the washroom. As she walked away, she turned around and held up her hand, fingers splayed.
"Five minutes," she mouthed. Our parents both had their backs to her, so only I could see her. I was so surprised I almost choked on the bread I was eating.
As I assured my parents I was fine, my mind was racing. I suddenly recalled that the stalls in these bathrooms had complete doors; solid and floor to ceiling. The men's washroom (and presumably the women's, too) had one handicap stall that was easily three times the size of a normal stall. As I tried to process the myriad possibilities, I felt my cock grow hard.
"Ben?" I heard my mom say. "Ben, are you okay?" I realized I had totally zoned out and hadn't heard a word anybody had said.
"Uh, yeah mom, I'm fine," I managed. "I think I might have eaten something funny today though. My stomach's a little off." I hoped that explained my current state. Luckily, the interruption had taken my mind off fucking my sister, so my recently engorged member was becoming flaccid. At least it had been until I started thinking about it. I needed to move quickly.
"Sorry, mom, dad," I said, hoping I looked sick. "I've got to go, bad." I practically ran out of the restaurant, compelled by something much more powerful than my bowels.
I approached the small sitting area outside the washrooms, and Rachel was nowhere to be seen. I didn't want to be seen standing around outside the washroom, especially by my parents, so I went into the men's washroom.
The washroom was empty, or at least seemed to be. Each stall door stood ajar, except for the handicapped one at the end. I decided to see if it was occupied, so that if Rachel came in here I knew where we could go. I rapped gently on the door.
"Occupied," came a voice. I started walking away until I realized there was something funny about the voice. I stepped back and knocked again. There was a cough, and the same voice replied.
"Occupied," the voice said.
"Open up, Rachel," I whispered. The lock clicked, the door opened and Rachel grabbed my shirt and pulled me into the stall.
"I was hoping you'd figure out where I was," she said. She wasted no time unbuckling my belt and yanking my pants and boxers down to my ankles. "Quickly, get your fucking cock in my ass," she panted. She turned, hiked her dress over her hips, grabbed the hand rail next to the toilet and bent forward. Her ass was facing me, and I noticed her wrinkled little anus was glistening.
I reached out with my finger and ran it from the top of her ass, down the crack, across her rosebud, and over her pussy. I put the finger to my nose and smelled it.
"Butter," she said. "I snuck a square from the table, and I put it in my ass. Now get your big prick in there before I scream." I saw no reason not to oblige her. I stepped forward with my cock in my fist, and placed the head at her puckered opening. With one smooth push I entered her completely. She groaned.
"Hurry up and fuck me," she said. "We don't have much time." I pulled out and pushed back in, knowing that with the excitement of our situation, I would not last long. I pulled out and was halfway back in when the bathroom door opened. I froze, and so did Rachel.
We stood there, silent and motionless, my cock halfway into my sister's ass. There were the sounds one would associate with a men's washroom; urination, flushing, hand washing. I hoped that whoever it was would dry their hands and be gone when I heard the last thing I wanted to hear at this time.
"Ben?" I heard my father. "Are you in there?" he asked. His voice was right outside the stall. I was paralyzed with fear. I felt Rachel start to shudder and looked down. Her eyes were closed, and she had one hand between her legs. She was making herself cum as our father stood less than three feet away.