How many times have you studied a friend or an acquaintance for certain characteristics and thought - dang, no one would believe a character could be that flaky? Or maybe you've read a character that just couldn't possibly exist in real life. Funny how truth is often stranger than fiction. I love watching TV shows that work with criminal profiles, but I find it hard to believe that there are that many folks out in the world that are seriously messed up. I know. I tend to look at the world through rose-colored glasses, hense why I write romance.
When I first started writing, I went to several workshops on character development. One of the key points mentioned was, "You don't want to do that. It won't endear your audience to your hero or heroine." Okay, so most readers love a tortured hero, but he can't drink to excess, sleep around, or smoke. Now granted, in real life if someone has a violent background, no family love, or has been betrayed in some way, he/she is likely to turn to a vice for solace. It's human nature.
I think rules have changed with the popularity of e-books. Authors have come a long way to break these steadfast rules set by the 1980s and 90s romance authors. There are still some taboo areas. Most authors avoid putting a cigarette in their hero's hands. For a contemporary book, it just makes him seem stupid (unless part of his growth is his willingness to break the addiction). However, for a historical, to have the hero smoke is true to the times.
So - what makes a hero? For me, heorism comes when unsurmountable odds are surpassed in his/her bid to do the right thing no matter what it might cost. Personal sacrifice makes him/her that much more memorable. In order for this to occur, though, the author has to have put in place internal as well as external conflicts. The character has to have believeable reasons for making those sacrifices. Otherwise, what's the point?