I've noticed that Blaise Zabini is always Draco's sex toy when written as a girl in stories. I'm not sure why, but even if they're best friends, there's always some sort of sexual thing going on there. But when Blaise is written as a boy, he's usually very loyal to Draco, and if they're not best friends, there's more of a friendship than there is between Draco, Crabbe, and Goyle. This isn't all the time, of course, but in general, those're usually the characteristics that Blaise is given.
And does J.K. ever say what Ginny's name is? Is it really Virginia, or is that the fandom kicking in? Or is it just Ginny, period.
I'm such an observant person. :)