I placed the tip of my cock directly against my sister's anal opening and pressed gently, but with gradually increasing force. She pushed back and slowly her asshole reopened for me and let me in. As soon as the head of my cock popped inside her ass she froze and I immediately stopped moving as well. A small growl of pleasure emerged from her and her back arched as far as it would go.

"You still okay?" I asked.

"Fuck yes, this is amazing. Don't you dare stop."

She started rocking back against me, not enough to really drive me any farther into her but just to encourage me to...