Shepard's story-telling invites curious readers to analyze the novel's plot for some sort of ethical insight. In Weston's character, we see a self-destructive man with manic episodes during which he pretends to have everything under control. To his wife, these seasons are just stupid power grabs. Their relationship is painful and troubled, and it takes them through seasons of distance and proximity until finally, they are facing the truth of their scapegoated daughter together, symbolized by a literal scapegoat in their home.
The names of the father and mother are very similar to the names of the children; Emma is like her mother, Ella, in her desire for escape. Eventually we see that Wesley also takes after her mother's escapism, though he insults her for it (no doubt his father's influence in his character). Emma also takes after her father, although Wesley clearly has more in common with Weston, as their names suggest. The way that Emma takes after her father is important though, because it brings the plot to its climax.
Ella is a stressed out woman trying to cope with intense emotional damage and frustration. Weston is a destructive and angry man who only controls his environment—not himself. So who does it sound more similar to when Emma takes a gun and kills everyone inside the Alibi Club? That is where Weston met his buyer, so the bad blood there is Weston's drama. Emma takes up her mother's frustration, but she does it with Weston's sociopathic anger. The result is an ultimate depiction of the family's dysfunction; she is reckless and self-destructive to the point of literal death. Although the death is coincidental, it is symbolically important as the conclusion of this family's struggle.
