I don't know why I fight against this notion that Chirugh and the Joker are human, but I do. It seems to me there is nothing left of their humanity; both characters have lost any sense of it. Seems to me the authors of these characters are making a statement, instead of creating a human character. And in both films, they are surrounded by very human characters that have both good and bad sides. But these guys are totally devoid of the good side.
(On a side note, I like how in TDK, the people of Gotham prove their humanity much to the Joker's chagrin.)
I guess it doesn't really matter. But hey, what wonderful performances by both Bardem and Ledger!
I understand where you're coming from on this--who can say what's in an author's mind when he creates a character like Chirugh? It can be as simple as the author just doesn't bother to give him a background or it may be a more complicated symbol of something entirely different.
Look at
Moby Dick--is Ahab pursuing just a whale or is he Man confronting Nature or the Cosmos or Fate? Is he really seeking revenge on a whale or is he fighting back against God?
How about Frankenstein's monster? In the book, the monster
is human. It talks and thinks, and one can only wonder what sort of memories it might have from beyond the grave. And it is motivated by revenge to bring down Frankenstein. In the Karloff film, however, the monster is recycled, patched together from various parts and brought to life in a process that even Frankenstein doesn't fully understand (remember he thinks at one point he's failed to bring the monster to life). In the movie, the monster is essentially a blank page with no knowledge of the world, no motivations, and so whatever he does is what he learns from the people he ecounters. In short, he's what society makes him, a mirror of our own evil.
Or look at the alien creature in the original
Alien. We don't even know for sure what it is because at the first encounter with a human it looks like a plant of some kind, and its pod bursts to scatter pollen or a seed of some sort that then becomes animal after incubating in the host's body. We can surmise that the alien is "motivated" to reproduce, to feed, to survive but those are instincts and not what I think of as a motivation where the creature makes a choice to act one way and not the other.
I haven't seen
The Dark Knight and therefore can't speak about that character. Chirugh, on the other hand, seems to come out of nowhere and makes no explanation of his action--much like the Man with No Name in
A Fistful of Dollars. At least we know Chirugh has a name and that he arrives on the scene in the company of two gangsters who we assume are part of a narcotics gang getting narcotics into the US from Mexico. We don't know why he then kills the two men, but it's evident from that and other actions and conversations that he's carrying out an assignment from someone, which does give him motivation--he's just doing his job. But can we judge from his actions if he's human, in that he shares some of our common humanity, or is he inhuman--sort of a punishment from God who strikes unexpectedly and indifferently like the plague?
Most of his murders occur in the process of trying to complete his job of regaining that suitcase full of money, so he is motivated by that assignment which he takes very seriously, almost as a point of honor in that he makes a point of observing certain standards. He's been given a job and he will complete it; he promised to kill a woman if her husband didn't comply with his demands and he sticks to that promise even though the husband was dead by then and would never know; and most telling of all, he allows certain victims, those on the fringes of his primary assignment, to live or die on the luck of a coin toss. That to me is the last vestige of Chirugh's humanity and he holds tight to it because otherwise he becomes a mindless monster killing anything that crosses his path. In his mind, the coin toss relieves him of all responsibility. If the victim losses the toss, it's the victim's bad luck, a whim of fate, because Chirugh would have let him go if the coin toss had gone the other way. If he wins the toss, Chirugh let's him live because in his own mind Chirugh honors his commitments. That's all that is left of his "good side."