About pushy characters...
In my experience, when a story is really on track, it has a life of its own. You end up writing things that surprise you. Characters take on their own identity and begin to do things that you didn't really plan for. They become pushy. This is a good sign.
Thunderstruck readers may be surprised to hear that Gail was one such pushy character. Way back in my original conception of the story, it was about Sharon's journey, and she quickly left her entire family behind. She had this sort of irritating religious sister who was, I am not terribly proud to admit, a pretty shallow figure... practically a caricature. They had some arguments about miracles, then Sharon found out some important things and pursued them on their own, bye bye family.
Only that sister, that stubborn, pushy sister, refused to just be one-dimensional. She had no interest in parroting simple-minded beliefs. She was a deep thinker, and her faith was something she wouldn't let me write off. Nor was her love for her sister... and Sharon, the troublesome creature, loved her back with just as much ferocity, despite their differences. Suddenly I had two central characters, not one, and I had to think a lot more about Sharon's whole family. And Thunderstruck became a hell of a lot more interesting.
The trouble with characters like this is they mess with your plot. They don't go where they're told, or do what you ask, or disappear when you want to be done with them.
I'm dealing with such a character now. He refused to be the simple jerk that I wanted as a plot device, he doesn't want to go away, and now Gail has decided she likes him. He's messing with my script.
So an author has the ultimate power and can force characters to behave however he wants, but I really think that severs your fundamental connection with the story and characters. The story breaks, perhaps irreparably.
But what you can do is kill a character. I think it's often a good idea to dust a character that the audience likes early on in order to show that the stakes are high. An early sacrifice. And I think I've just found my lamb.