Day 1
The first rule, as he well remembered, was to synchronize their behavior with each other. Because they worked together, or at least near each other for most of the day, it didn't took long for him to be in perfect harmony with Tony.
It was easier to do that when they were talking, though in these moments he had to be more careful not to be too obvious. If Tony was gesticulating a lot, he did the same thing, if he acted more restrained, so did Bruce. He leaned slightly forward seconds after the engineer have done the same thing, to turn away only when the other already had.
Sometimes he watched as Tony almost imperceptibly moved toward a tool, and then handed it to him without even making eye contact. It was as if he could foresee his thoughts, by using every little sign to know what to do next.
This type of seduction was slower, but it offered spectacular results. In just a few hours, Tony already seemed even more comfortable in his presence. He could feel the mask he wore to be lowered, even if only a little. They moved like one mind in two bodies, and by the end of the day, Tony seemed to be anticipating Bruce's moves too.