In my opinion, Dean was an optimistic and irrational fool in the beginning of the novel and progressively became more depressed yet still irrational. However, it is likely that Dean will mature later in the novel. As for now, he still seems both illogical, immoral, and irrational because of the way he acts with the women in this novel, the way he giggles nonsensically, and the way he lives life in general. On the other hand, he is increasingly improving his status. Examples of this is the house he bought, his job, and his child, which will improve his responsibility in the future.

Also, I think another important aspect of part 3 is the stronger friendship between Dean and Sal. The situation where Sal tells Dean his plans to go to the east and then to Italy is a significant moment where they truly connect. Another example is when Sal defends Dean when Galatea and the others reprimand him.