My stepsister looks like the sweet, dozy, well-behaved type. She isn't. She plays at being oblivious while making sure her tits are always in my eyeline, and the fun for her is walking the line where I can't tell if it's deliberate. Eventually the teasing wins and I hit my limit — I come up behind her and grab them with both hands. Turns out that's exactly what she was waiting for. She switches on hard and starts asking for my cock herself. No way we're going back to being brother and sister after this.