I think there's merit in writers trying to work out why certain character types do this. If you understand why an archetype resonates with the audience, you can either exploit that to create deeply compelling characters, or eviscerate it to forge a potent social satire. Either way, the reader is going to remember your book.
In this post, Jaye talks about why we love vampires. This is a wonderful bit of serendipity because it's a subject I've been thinking about recently. About a week ago, I came to a conclusion about why we like those sexy, gorgeous vampires so prevalent in urban fantasy. (And on the heels of that conclusion came a story idea. Yippee!) Here's how I explained it in Jaye's comment trail:
I think we like vampires for the same reason we are envious of Paris Hilton's lifestyle. We wish we were perfect, beautiful, powerful, desired and esteemed. We want to live a life of pleasure and excess without any moral reservations. We desire an existence containing all of life's pleasures and none of its pain or responsibility.
In other words, we want to be greedy, shallow and evil without feeling guilty about it or paying for it. And we want this state of affairs forever.
Or to put the same idea in less charged terms, I think we love vampires because they are humanity's most selfish dreams personified.
Of course, that's only one possible explanation. People have lots of reasons for liking vampires--one of the foremost being that bad boys make tremendously sexy love interests, and you can't get badder than a predator.
The best thing about thinking about what makes a certain archetype popular is that if your explanation is right, you will create a story that socks the reader in the gut, and if you're wrong, your story leaves readers impressed with your imaginative re-invention of a character type they thought they'd seen every iteration of. It's a win-win situation for a writer.
As a side-note, I think Tolkien-style elves are popular for reasons similar to vampires', except they lack the component of evil. Tolkien's elves were also beautiful, esteemed and basically immortal. They also didn't seem to have to deal with life's pain, and their responsibilities were clearly not troublesome to them. Like vampires, they lived an apparently graceful existence; the elves weren't bad-asses, however.
This reflects the audience. Some readers respond better to the idea of being perfect and without care, so long as that doesn't mean without morals. For these people, elves rule.
What are your favourite stock characters in fiction? Which ones always capture your heart even though you've seen them in a hundred different guises? Can you pinpoint why they affect you that way? Can you parse what makes humanity in general respond to that kind of character?
And since we're on the subject, are you an elf person or a vampire person? (It's a little like being a dog or a cat person.) :-)