How does Batman's character evolve throughout the story?

Does Harvey Dent become more evil as he transforms into Two-Face or does his evil just become more obvious?

Why might Batman be an ineffective force for fighting evil in Gotham City?

What is the significance of Harvey Dent's transformation into Two-Face?

Who is the more moral character in the story: Batman or Chief Gordon? Why?

How is Batman similar to Harvey Dent?

The phrase "what needs to be done" or some small variation of it appears in the book numerous times. What do the characters mean when they say this?

How does Batman's conception of how he must fulfill the pledge to his parents change throughout the book?

According to the book, can the ends justify the means? Why or why not?