Plunging Off the Slippery Slope

Easily the most fascinating part of Brighton Rock is the cast of characters.  Although it would be easy to dismiss many characters as insignificant and unimportant, or simply uninteresting, the director takes pains to give each one a complicated personality.  Big-time gangster Colleoni appears in exactly two scenes, and yet he is wonderfully captured as a smirking sybarite with playboy airs.  Spicer is a supporting character who is knocked off with surprising speed, and yet he appears as one of the most sympathetic characters in the entire film.  Even Kite, who is killed immediately, is given a disproportionate amount of characterization and backstory.  However, the most important characters in the film (and those with the most interesting roles) are Pinkie and Ida.

Ida first comes across as a typical high-society socialite; elitist and wealthy, and ultimately shallow and selfish.  It seems that she typically tends to act this way, too.  Rose is at first surprised that she is taking interest in her affairs, and then becomes suspicious, saying that Ida "doesn't care about her".  And at first, this seems true: Ida is really only interested in finding proof in the murder of her friend Fred.  However, as the film goes on, Ida's characterization begins to pick up.  She is convinced that Pinkie killed Fred, but ignores the murder in favor of protecting Rose.  She does everything in her power to care for Rose and tries to take care of Pinkie legally.  And when that doesn't work, she turns to less legal methods, contacting Colleoni and seducing Cubitt, all for Rose's sake.  She is turned, across the course of the film, from a somewhat selfish and unsympathetic character into the only positive influence that Rose has.

Pinkie, on the other hand, is given the opposite characterization.  We see him at the very start of the film distraught over Kite's death, and later appearing scared and innocent under Fred's knife.  However, after killing Fred (which was, to a certain extent, self defense) Pinkie takes a nasty turn for the worse.  His treatment of Rose, first scaring her with acid and later threatening to push her off a cliff, is the start of it.  This moves quickly to conspiring with Colleoni, and enemy, to kill Spicer, a longtime friend (of course, when Colleoni doesn't finish the job, Pinkie does not hesitate to do it himself.)  Of course, wracking up murders is not enough for this particular psychopath: by the end of the film, Pinkie is trying to convince Rose to join him in a double suicide (and seems willing to kill her himself, along with another friend.)  Whereas Ida has become a force for good in Rose's life, Pinkie becomes an increasingly bad influence on her.

The one character that does not develop much at all is Rose.  She is, the entire time, blindingly faithful in Pinkie.  Even once she has realized that he is a murderer (which Ida had been trying to tell her for most of the film), she does not leave him; instead, she marries him.  She goes so far as turn a knife on Ida, joining Pinkie in his plunge into madness.  Her character exists to be influenced by the others, and while she herself does not have much interesting development, she is the one who influences the others in their own development.  It is because of her that Ida becomes a force for good, and because of her that Pinkie falls into insanity.