As I mentioned in the 1st part of this "multi-post", this post is about the concept of "femme fatale", specifically film noir femme fatale. A femme fatale is a villainous woman who uses her sexuality to achieve her (usually selfish and maquiavelic) own gains. The expression is obviously french, meaning "fatal woman".
She is often portrayed as a sort of sexual vampire; her dark appetites were thought to be able to leach away the virility and independence of her loves, leaving them shells of their forver selves. Only by escapign her embraces could the hero be rescued. On this account, in earlier american slang femme fatales were often called vamps, a word that is associated with the fashions of the 1920s. (this paragraph is taken from www.jahsonic.com)
As I said in the earlier post, the femme fatale is in my opinion one of the key elements of any film noir because she is usually the main trigger of the drama and as a consequence, the fatal ending of usually all main characters in the story. In short sentence we can describe the femme fatale as a selfish bitch who basically creates the whole mess and tries -unsuccessfuly- to get away with it when the whole plot is discovered.
Femme fatales are usually portrayed as independent strong individuals with brains (something socially unacceptable back in those times). This, combined with a strong attractivenes and beauty, configures a deadly weapon to use successfuly on any man.
Very often, the storyline is as follows:
She uses her strong sex appeal and beauty to seduce fragil and disillusioned main male character into committing a crime (usually murder). They fall in love (although I usually suspect that she usually pretends but you never know in those films as everything is done "subtly"). He loves her so much that he committs the crime. By doing so, he trapps himself into her diabolic persona. He can't get away from her now. He has become a criminal, like her. When they get caught, usually the consequences are fatal for either him or both. But mainly him.....(You usually feel sorry for him, at the end).