He caught me fucking his s****r SeXStoRY

My GF's 16 year old son had come to stay for the week. He lives with his father who had to go out of town on business. He had gone to the mall with some buddies one afternoon. I was home with his s****r Maria and was feeling very horny. I went to her room and asked her if she wanted to fuck. She said yes but she had plans to go out soon so it would have to be a quicky. We got undressed and I laid her back on the bed and slid my cock into her. I was pumping her pussy hard and fast, lost in the pleasure of the moment. We didn't hear her b*****r come home, I actually forgot he was staying with us. He must have heard us and came to see what what was going on. He walked into the room just as I shot my load. Maria jumped up and ran to the bathroom. I grabbed my clothes and went to my room. A few minutes later Maria left the house. I went to David's room to talk to him and asked him if he would not tell his mother. He said he would keep it a secret on one condition. I thought he probably wanted me to give him some money. I said "What will it take to keep your mouth shut?" He looked me in the eye and said "I won't say anything to mom if you give me a blowjob and let me suck your cock." It came as a surprize to find out he was gay. I made him promise not to tell and told him to get undressed. I watched as he got naked and I took off my clothes as well. He had a slim smoothe body with hardly any hair. His soft cock was only 3 1/2" long, kind of fat with a nice big head. He sat on the bed as I got between his legs. I sucked his cock and balls into my mouth running my tongue all over them. After several minutes he had just started to get hard. I asked him if he liked the way I sucked him. He said yes, but what really turned him on was having a cock in his mouth. I told him I could take care of that and stood up. He started licking my semi hard cock and rubbed my balls. My dick stiffened as he took all 7" of it in his mouth and sucked hard. I looked down and saw that his dick had gotten very hard and he was stroking it. It was now about 5" and precum was begining to drip from the tip. I told him to lay back so we could get 69. I laid beside him and we continued sucking each other, his little cock throbbed hard in my mouth. His precum tasted sweet on my tongue as more started to ooze out. He pumped his cock in my mouth and I felt my balls begin to tighten. He said he was ready to cum, I sucked him deep in my mouth. A few seconds later he began squirting his load and I quickly did the same. His cock went a little soft after he came, I continued sucking him as he jerked on my still hard cock. To my surprize he started to get hard again and soon he shot another load into my mouth. I laid there sucking him as he jerked me till I came again. On his last day staying with us we did it again. It was fun sucking his young cock and having him suck me off too. I told him he should get his dad to let him visit again soon and I would try to get his s****r to let him watch us fucking sometime.