It hadn't previously occurred to me to focus on anything; I've always delighted in Austen's wonderful prose and ideas without paying a lot of attention to what was going on (except of course to understand and enjoy it).

Several others have mentioned focus, however, and that provoked me to start an organized, detailed look at one of the subjects that I've participated in long but cursory (:-) discussions on: Darcy's progress through the novel. So, here goes; I dive into the first 12 chapters.

Chapters 3 -- 6: Meryton assembly and party at the Lucases'
Here we first hear about Darcy. He's quickly identified as very rich, very proud, utterly silent. Even Bingley's entreaties can only provoke Darcy to a few sentences of disdain of the company, then a (deliberate?) insult to Lizzy.

We're not privy to any of his private interactions with the Bingelys except the discussion after the Assembly (chapter 4). A single comment from Darcy is recorded; it's not unreasonable to infer a real conversation, but none is indicated.

When he does speak, it is always dismissively until chapter 6, when he (possibly) tries to initiate a conversation with Lizzy by asking her at the Lucases' to dance. This is aborted by Charlotte; there are no more words from him except the "fine eyes" comment. Caroline goes on at length, but there's not the least indication he participates.

Chapters 7 -- 12: Netherfield
He has some brief comments in response to the Bingley sisters' pestering, and a dismissal of the Bennet sisters' marriage prospects in response to Bingley's defense of Jane and Lizzy despite their low connections.

His first attempt at a real conversation as far as we know: he is drawn into a very unequal conversation with Lizzy regarding "accomplished ladies". Caroline starts it, but is quickly eclipsed by Lizzy's sparkling banter and Darcy's determined and intelligent, but dull responses. At least he's participating.

After more attempts to join conversation, which he cannot sustain for one reason or another, he is dragged into the conversation about Bingley's character. From here on he tries to be nice to Lizzy, defending her when she's not present, and attempting to talk to her when she is. Lizzy rebuffs him, which paradoxically attracts him even more.

Darcy is pleasant to Jane when she finally recovers enough to join the hosts.

Darcy rebuffs Caroline's attempts at conversation, then is drawn into the celebrated exchange about the faults of pride, vanity, and temper: another unequal exchange which quickly buries Caroline and overshadows Darcy, but he is clearly beginning to participate.

When Jane and Lizzy leave Netherfield, he makes a point of ignoring Lizzy all the last day, since he's afraid of hurting her by making her think she has a chance to conquer his heart and gain the high status and wealth he possesses.