Your characters are the foundation to everything you write. They will often challenge or even surrender to the circumstances you impose on them because of their wants, needs, fears, and resentments. Those four elements are vital to propelling internal conflict which in turn shapes the way your characters react to external triggers in their life.
The interesting thing about Tony Montana in Scarface is that his character does not change, he succumbs to his own fears and resentments. Tony is the same ambitious, paranoid, greedy man from start to finish. But once he loses what he needs, his wants soon follow as his fears and resentments overwhelm him. Tony’s journey, all the pain he endured and caused, was inevitable due to his refusal to change for the better.
What drives your characters to make the decisions they do? Your characters all have individual short- and long-term wants, these will often be affected by external conflicts and their needs, fears, and resentments. A short-term want will lead your character closer to their long-term want and, ultimately, their need. Tony Montana wants to succeed at any cost and fights dirty since he has nothing to lose, not at the start anyway.
An example of a short-term want in Scarface is present right at the beginning of the film. While in a detention centre in Miami, Tony is given the opportunity to get a green card–his short-term want–courtesy of Frank Lopez if he assassinates Emilio Rebenga. Tony kills Rebenga without thinking twice.
The main arc of Scarface sees Tony strategically placing himself in circumstances where he can gain more control of his external state. This is obvious in his collaboration with Alejandro Sosa which weakens Lopez but raises Tony’s position. Tony is out for himself, and by weakening and later eliminating Lopez, he is one step closer to becoming powerful and insanely wealthy–his long-term want.
A need often relates to an emotional or psychological absence in your character. Your characters–like real people–will often deny or ignore their needs and focus on their wants, especially if their external world creates conflict where their need should be fulfilled. Your story is reliant on the decisions your characters make to fulfil themselves.
Elvira Hancock cruelly rejects Tony, she wouldn’t be with him even if she were ‘blind, desperate, starved and begging’ for sex. This leads Tony to pursue his wants, because he believes it will buy what he needs. Tony’s idea of success relies on Elvira’s acceptance of him, as shown in his admission, ‘With the right woman, there’s no stopping me. I could go right to the top… I like you the first time I laid eyes on you.’
The main point of the argument that causes Elvira to leave Tony is about how they can’t have children. Tony concludes that all the fighting and killing to achieve his wants has amounted to nothing. He can’t get what he needs with Elvira, they can’t have a family because of their addictions and criminal lives. And as her acceptance fulfilled Tony, her separation from him at the end of the film deprives him of his need.