It's not easy being the parent of a couple of hormone driven young-uns, but that's exactly what I became when I married my wife, and my son and I moved in with her and her daughter. I sensed from the beginning that there was a little awkward flirtation going on between the new siblings, what else can you expect when you put two horny college students under the same roof? I never thought that anything would become of it however, I figured that the taboo of being step brother and sister would be enough to keep things under control. Boy, was I wrong. My wife started working opposite shifts from me, and put me in charge of getting all of the household supplies. She gives me a list, and I'm responsible for making sure that the house is fully stocked with enough to feed a family of four. I wrapped things up pretty quickly at the store and headed back home early. The house was strangely quiet when I went in, with no sound of music or television. I thought this was a little strange, so I tip-toed down the hall towards my step-daughter's room to see what was going on. There was a light on and her door was open pretty far... far enough for me to see my son getting a blow job from his sister! I was shocked! I couldn't believe that they were doing that, and I wondered how far they were going? Were they fucking? What was their mom going to say? I watched for a little while, and before I knew it, I felt my cock begin to stir in my pants. I just couldn't help it, I was angry, but I was turned on watching my new daughter take my son's big cock all the way down her throat. Her mom never did that to me. I backed up and decided to pretend I didn't see anything, and I must have bumped into something because suddenly they scrambled to get my son out of his sister's room as quickly as possible. I gave them a few minutes to get themselves together, before deciding that my daughter needed to be talked to about what was happening. I'd spare my son the embarrassment for now, and deal with him later. When I walked into my daughter's bedroom, she was pretending to be resting at first. She "woke up" and asked what I was doing home so early. I told her that I've been home for a while, and was very curious about what I saw happening on her bed. She acted like she didn't know what I was talking about at first, but soon realized that they were busted. She glanced down and must have seen the raging hard on that was in my pants. "I think you like what you saw", she said. "You know, I could do the same thing for you that I did for him. Just promise not to tell my mom, ok?" My new daughter told me to lay down on her bed and said that she wanted to see if my son takes after me. She slid her hands over my pants and felt my hard cock. "I can't wait to play with yours Dad." She pulled my pants down around my ankles and slipped her hand up inside the leg of my underwear to grab my cock in her little hand. She spit on my cock and started to stroke her hand up and down the shaft, as my cock grew in her hand. "Don't worry Daddy, I won't tell mom. I think I like your cock better than my brothers!" Her double handed stroking technique was driving me crazy. She was much hotter and better at this than her mom is. She was driving me crazy by calling me "Daddy" over and over. Then, she confirmed my worst fears - she was fucking her brother! At night, my son would sneak into her room and fuck his sister in the room right next to ours. While my wife was in dream land from her medication, my son was getting all of the action with his hot young girl. She kept stroking, and telling me that I could fuck her too maybe. The thought was dangerous, but made me feel like I wanted to explode. She twisted her hands and pumped them up and down, milking a load from deep within my balls. Before I knew it, two huge shots of cum flew over two feet high out of the tip of my dick. I can't remember coming like that since I was my son's age. I think things around the house are going to be a little awkward from now on. Starring: Sadie Holmes