Curious, I tiptoed into the hall, detoured through the dining room and peeked out into the entrance hall. Looking up the stairs, I spotted my sister, ...obin, 'riding' the bannister, one leg on each side, going up and down. As I watched, I could see that she was not wearing panties, her bare pussy was scooting up and down.I'm no fool, I knew what this was. Pretty inventive too, for a thirteen-year old. Soon, she began to moan, rubbing faster and faster. Then, she orgasmed as her body shuddered. I removed her shirt buttons. She was in white bra.I held her boobs and started kissing around the neck and earlobe. She was taking deep breath. Removed the shirt. She didn’t say anything. Unhooked her bra. Pushed her on bed and starred licking her boobs. She was holding my hair and enjoying it with little moans ahhh ….. ahhh … Then I gave a gentle bit on her nipples. She was shouting aahhhh. Then I removed her pant and panties. She was completely naked and came to senses. Tried to cover her. She was enjoying it too, he could hear her faint panting on top of him. He began to stroke her little clit with his thumb, while continuing to hold her body tight to him with his other arm. He had never enjoyed a sexual act as much as he was enjoying every single thrust into his daughter. He fucked her like this for what seemed to be an eternity. Time slipped away as they silently bonded in this new wonderful way. So tenderly he loved her. He whispered in her ear what a good girl she was, how. All the way to his balls. Then he began to jackhammer my ass like there was no tommorrow. This time he pounded my ruined asshole for a good ten minutes before his knot began to grow. I felt his knot popping in and out of my loose ass as he fucked me like a pornstar could only dream of fucking. Finally, his knot grew too big to come back out of even my stretched sphincter, and we were tied. Knotted again. Fuck! My asshole was burning! But, my cock had already risen to granite or limestone.