Because we relate to them:
Human beings have rough edges. Authors who write exclusively about ethical, admirable, likeable characters are not writing about real people. … Good stories require mistakes. If you want to read about unimpeachable characters, order the annual report from Oxfam. If you want to read about difficult, complicated, maddening characters who remind you of people you know – who remind you, if you’re honest, of yourself – read Shakespeare. Read Dostoevsky, Tolstoy, and Flaubert. Read Wilde, Updike, Roth, Yates, Wolfe, Woodward, McEwan, Hornby, Hollinghurst and Shriver.
The Dish 