Realizing Characters

On her blog yesterday, Patti Abbott discussed fully-realized characters, ending with the question, "What characters are memorable for you? Who walks off the pages of a book and into your memory?"

I commented:

To me, perhaps as much as half the responsibility for realizing a character lies with the reader. Part of the writer's job is to give just enough detail to let the reader's imagination go the rest of the way.

Offhand I think of Holden Caulfield (CATCHER IN THE RYE) and Alonso Quijana (DON QUIXOTE) because they resonated with me and my experience when I first read them (in high school and college respectively).