>>Rock shakes Balalaika in the anime???
This is why anime be DANMED!!!
As for manga, Rock is well, your typical guy who eventually assimilate into that world of psychos in his own way, as he lacks the violent prowess the other has. And he eventually comprehends how moral or common sense is useless in that world. But yet, he still act like the good old man he is, just because he feels like it. And this is what got him off the hook from Balalaika once, because it ultimately proved they are the same type of people. Though, he is also starting to lose it, but in his own way too. How do I put it, he is starting to take pleasure in making people to play along with his goody goody ways. In the psycho maid arc 2, he is actually having fun in figuring out ways to get Garcia unharmed out of this.
As for Revy, she is much more straightforward despite how she behave on the surface. She is just trying to live, just being a cracked up psycho is the only way she had learned how to live. Her back story is not fully explained, but we can be sure she is caught deep into some dirty US politic in the past. She is, I am not sure understanding is the right word, but is very tolerant to Rock's way and know what merit he has and where he is coming from, but still never really agreed with him.
As for Balalaika... she is just a woman who never recovered from the post war traumatic syndrome and still wants war every day and night. But she is good at it and no one can stop her.
The manga's plot is pretty episodic like the anime does, with "there are evil US politics going on" hints from time to time and I can see the CIA nun eventually raise as a boss character of sort. But the manga still mainly digs on the characters and their philosophies. Meh, I'll just say read the Japan arc and psycho Maid arc 2, you'll get a pretty clear idea on what the manga is trying to do.