She encourages it

“Wow that’s hot” she says, biting her lower lip. You are too caught up and **** to realize she wasn’t stopping this, instead your twin walks up behind you, pinning you to her girlfriend, not letting you break away from her kiss while guiding the two of you to the couch in the living room. You are kept pinned down, now between the large woman and the back of the couch. When she finally breaks the kiss, she simply moves up, forcing you to suckle between her large breast as she starts kissing your sister behind you.

She grinds her very hot groin over your skirt, your bulge aroused but getting no relief. You instinctively kiss and suckle all over the girlfriend’s breasts through her top, only once you’ve covered everything she pulls off of you a bit, allowing you to look up as they both look down on you.

“So, Mistress, this is Billy.” She introduces you. You should be concerned by the title, but your frail 18 year old mind was partially broken and unable do any critical thinking. “Billy, this is my Mistress. Would you like to play with us?”