[That little bit of fight has much the same effect as the challenge when they were coming back from the pizza shop. It makes him feel adventurous and a little bit daring, which for him is a pretty big step.
He tilts his head a little, but instead of just pressing back into the kiss he kept a breath's worth of distance and then, ever so slightly, he traces her bottom lip with the tip of his tongue. It's brief, tentative to the point of being barely noticeable, but it's definitely a step forward.]