Community
One of the main features of the story is that its urban setting fosters a sense of community among the characters that mirrors the community feeling of Harlem, for instance. This "doing what's best for the neighborhood" thing is at the heart of the stories.
Special power and responsibility
With ability comes responsibility, which might be called the 'response to ability.' This means that to the degree the characters in the novel have been given the power to make decisions and execute them with power, they are also responsible for the consequences and for their decisions whether or not to help, or even whether to do wrong.
The difficulty of right and wrong
One of the reasons Watchmen was so successful was the way it reframed the typical portrayal of heroes and villains. For instance, there are implications in the book that each of the characters has good and bad qualities. They aren't like Superman, whose morality is upstanding. Manhattan flees to Mars after a conspiracy theory comes to light that he is giving people cancer. That's the kind of complexity that appears through the entire story.
