One of the tricky parts about writing a series over the course of a long period (it's been nearly a decade since I first wrote the name Lenox down on a piece of paper, thinking it might make a good name for a protagonist) is knowing how much characters should change.

There are protagonists who never, or rarely, change - Miss Marple, Sherlock Holmes, Robert Parker's Spenser. Then there are those who grow and change and even die, like those of Elizabeth George or Sue Grafton or PD James.

I like both methods. I think the second is riskier - you can alienate the reader, or lose sight of what made the character interesting in the first place. (Since the author spends a LOT more time with the characters than the reader, it's tempting to make unnaturally drastic changes, just for the excitement.) Elizabeth George's books have been worse to me since she killed off a major character.

I try to have my characters grow and evolve, and at the same time stay somewhat static - so that visiting them in the sixth book and the first book doesn't feel like THAT different of an experience. They're still the same people, with the same qualities and fears and loves. This seems to me true to life. It's uncommon to see people take huge turns. More often you see people deepen into their characters.

What do you prefer - characters trapped in amber, or characters who evolve in crazy new directions? What's your favorite example of one way or the other? Curious as a writer to hear how readers react to this subject.