I don’t think we can write credible fiction without it.
We can’t write a character without getting inside their skin and imagining what they would do and say in the situation we are putting them in. That means our own experience and history, our own dealings with other people in our life come into play in fleshing them out.
Does that go for the antagonist too? Oh yes, even more so. No hero can be stronger than the villain or situation they are up against. Captain America called in the find out who is stealing someone’s newspaper would be a very small story no matter how strong a hero he is.
For a writer this is rather like “going to the dark side.” It doesn’t mean we have done wicked things we can call upon to write about, but we can imagine them. Sometimes it can be scary how well we can imagine them.
I hear writers all the time talking about “I cried when I wrote that,” or “I scared myself with that scene.” I’ve done that. But it’s a good thing. How can we expect to raise emotions in someone else that we haven’t experienced ourselves? We have to be writing our own emotions into the piece.
So we are drawing on our own experiences, on our own emotions, and we are probably drawing on our own friends, family and acquaintances as well as those we come into contact with to flesh out characters and give them life. I know a number of authors who like to go the the mall or airport or some other public place just to watch people and get ideas for characters.
Putting ourselves into our characters shoes to imagine what they would say or do, the operational word is “ourselves.” No matter how much we are trying to be someone else, it’s still us. And when we are writing some character doing some really wicked things, you may stop as I have and say to yourself, “Wow, where did that come from?”