Warning: Post contains metaphysical blather.
A friend once asked me if I felt sad whenever I finished writing a book.
I don't feel sad, though there's a certain bittersweet feeling. If I got the ending right, my emotions are similar to those you have when hearing the last note of a piece of music, or the final scene of a movie. It has to end, and no matter how enjoyable the journey has been (even though you may think "I don't want this to end"), the ending, if done well, makes you think, "Yes, this is how it's supposed to be." A feeling of completion.
The bittersweet comes in when I think about the characters. By the time I near the end of a book I've spent hours thinking about these people, and being in their heads. I know them better than I know many real-life people, including tons of details that don't make it into the actual book. And although they are my creations, by the end I see them almost as guests in my mind.
In the acknowledgments for The Color Purple, Alice Walker thanks all the characters for coming to the story. I didn't understand this sentiment before I started writing but now I do. Now I wish there were a way to throw a wrap party and say thank you to all the characters who made telling the story so much fun.
Because characters are what it's all about. You can have a dizzying, glorious prose style or a pulse-quickening plot but if the characters are cliches or ciphers, there's going to be a hollowness at the core of your story. "What's going to happen to these people?" - that's the question that often drives me when I read a story. And not just the heroes, but the villains as well. A fine example was Stephen King's Under the Dome: I could not wait to find out if one particular rat bastard was going to get his much-deserved comeuppance.
For me, one of the hallmarks of a great novel is how much I think about the characters afterward. Even though I know they're not real, I wonder what happened to them, did things work out OK, and so on. But I know I can't have that. All I can do is thank the writers who came up with these people.
As for my own characters - guys, thanks for showing up. I know I put some of you through hell, but I think you'll understand that's what had to happen. (If you're mad, blame the Muse - I've got Melpomene's number here somewhere...) Anyway, thanks for being the guests of honor in my brain. I couldn't do it without you.