You get a text

The guilt and arousel swirling around your head all come crumbling as a text hits your phone, your sister, naked, on her knees, mascara running down her face, lipstick smeared and cum dripping from her forehead, all shadowed by the big dick she's salivating over.

The arousal becomes unbearable so you lower your pants and rapidly stroke your erect dick, it doesn't take long for you to cum and as you begin breathing heavy you get another message.

Its just a video of you jerking over you sister along with 3 words.

You're both mine.