In Carrie Fisher: Life on the Edge (FSG/Crichton, Nov.), Weller explores the life and career of the “badass” writer and actress, who died in 2016.

What drew you to Carrie Fisher?

There is almost nobody more complex than Carrie Fisher, somebody who could be so tough and sardonic and unsentimental, then really break down in tears, really need and want company. It’s hard to find someone who had so many juxtapositions, and a lot of that came from pain. The bipolarity was always with her, the inherited drug addiction was always with her, whether she acted on it or not. That was a double whammy, and yet she was incredibly productive. She never stopped working.

Are there similarities between Fisher and the women you profiled in Girls Like Us, your 2008 biography of Carole King, Joni Mitchell, and Carly Simon?

They were all iconic. They had fascinating lives, they had fascinating people in their lives, and they were constantly productive. And nothing kept them down. Whether it was bad romances or personal tragedies, they made material out of it.

Fisher had major substance abuse issues. What challenges come with writing about someone with such a complicated past?

The challenge is to remain sympathetic and empathetic. I wanted to show her in all her forms. The challenge is being honest and not sugarcoating it, to have the reader be there with the person, feeling what they’re going through.

You write that Fisher became a role model for young women at the end of her life. Why do you think that was?

Because she was so honest. She died at a time when we had just elected a president, Donald Trump, who made a virtue out of dishonesty and has made an absolute success of dishonesty and people loving him because he’s dishonest. So her honesty, which was fierce, which was a 10 on scale of one to 10, was something that I think lived with us a little bit unconsciously as the Trump presidency moved on.

Fisher was known for her legendary parties. What made her a people magnet?

She said it herself, I want to have a personality big enough to explode in the sky on New Year’s Eve over Hong Kong. That was something she wanted as a child. And she achieved it. There are people who are naturally charismatic. Some people just have it. She had a personality, a sense of wit, and she truly cared about other people.

How should Fisher be remembered?

Carrie had bipolar disorder and I think one of the most significant legacies of her life was destigmatizing that in a very strong way. She let you know that mental illness is chronic, and even if she feels better and looks totally great for a period of months or years, it is a chronic disease. We need empathy for it and laughter. That was one of the hidden lessons she gave.