She had the most intense shaking orgasm I had ever seen her have. He almost immediately pulled out and came all over her stomach and tits.
It was as if he had been saving a life time of cum up for just her. He covered her entire torso in cum and she rubbed her tits with his cum as she moaned. After he came, he laid his dick back on her lips and she reached down and grabbed it and slid it back inside of her. They sat in that position on the bed with him on top of her and his dick just resting inside of her.
She rubbed the back of his head and pulled him in for some more intense kissing. I could see red marks all down his back, she had clawed him to pieces. As he pulled out one final time they gently kissed and he gave her nipples one last goodbye kiss. Without a word, he slid on his boxers and was gone.
For the next two hours, she could not get her body to stop moving. She was rubbing herself on the bed as we talked about it all again.
As we started having sex again, I asked “did you like cumming on your brother’s dick?”
“Yes.” she would moan.
“Did you love having his giant cock slam you like that?”
She gasped “oh my god yes, yes”.
She looked me dead in the eye “am I bad girl, do I need to be spanked?” I put her over my knee and gave her the slutty spanking she deserved.
I don’t have any clue what type of pandora’s box I opened here. I know it feels safe because the world would never let them be together, so as far as threesome partners, that’s a big plus. But I am also positive now that the line has been crossed, they are likely fucking all of the time even without me around. Get what you wish for I guess, but damn does the thought of it still turn me on.