How does Harper Lee bring out different aspects of Atticus?

I think you could answer this question by looking at the
different "roles" we see Atticus in.

1. Father:
   consider how he treats his children when he deals directly with father-children
   lessons.  He does not treat them like children in the way he talks to them, but he also
   does not let them see him worry or struggle with adult
   problems.


2. Brother: when Aunt Alexandra (and Uncle Jack)
   Scout talks about "overhearing" conversations (which she frequently isn't giving the
   complete truth of the situation as a result).  Nevertheless, when he is dealing with his
   brother and sister, he acts very differently than he does with his
   children.


3. Neighbor: consider his attitude toward Mrs.
   Dubose.  Also consider how he acts around his lifelong friend Miss Maudie.  Both very
   different from Atticus as father, but also very different from each
   other.


4. Lawyer: Scout and Jem see a completely new side of
   their father in the Tom Robinson trial.  For Jem, this solidifies his admiration.  For
   Scout, who is younger, she has mixed emotions of fear, pride, and
   confusion.

Through the different roles Atticus
plays, and Scout's observations of these roles, the reader gets to see many different
aspects of Atticus' character.