Jason

From the very beginning of his chapter, Jason Compson makes his malicious and corrupt nature known when he says "Once a bitch, always a bitch, what I say". This essentially sets the stage for all of the misogyny intertwined in his southern ideals, especially when it comes to his sister Caddy. He makes a habit to blame her for every misfortune that comes his way and he, along with the rest of southern society, has a tainted view of her due to her promiscuity. 

The "new system" of the Compson family is basically Jason becoming the patriarch of the family now that Father and Quentin have both died, leaving him as the male head of the household. Jason does not handle the role appropriately by any means, but rather exploits it tirelessly by abusing (primarily emotionally) the rest of the family and conniving for his own personal gain without regard for the common good for the family. 

The narrative structure is the framework for how a story is told whereas characterization is the description and revelation of characters. As the story/plot line progress, Jason quickly begins to reveal his true character.