Micah and Nathaniel aren't entirely out of the blue. It was hinted at in Flirt that they were comfortable interacting with each other in the bedroom in Flirt, but not quite so comfortable about public displays of affection. And the think you gotta keep in mind is that Bullet takes place a full year after Flirt, so there's an awful lot that happens "off stage."

The other part that sticks in my brain and won't come out is later during one of the orgy scenes, Anita's watching Jean-Claude with one of the other women and she thinks that yes, she'd love to see the men do that with other men. Wow, really? Surely Asher and JC are facepalming because they could have demonstrated this eight books ago.