Did you see the episode when they are killed yet? It was the most disturbing anime episode I have ever seen. I almost couldn't watch it.
http://www.youtube.com/watch?v=bPuDpyHt2b8
http://www.youtube.com/watch?v=tSiQmB9bsqM&feature=related
I felt bad for those poor twins. But they played with fire messing with the Russian mob, more so by screwing with the sadistic Balalaika who gets off on killing.
Black Lagoon is a social commentary, it has a lot of truth in it.