When it came to selecting the lineup for "Suicide Squad," writer/director David Ayer had a deep bench from which to choose. After all, dozens of costumed criminals have been part of DC Comics' Task Force X over the past three decades.

"Deadshot is a no-brainer," the filmmaker explained to journalists visiting the film's Toronto set, "because he's just a core element of that team." And Boomerang was enlisted in part because he's "evil-chaotic." But what about Harley Quinn, the fan-favorite antiheroine played by Margot Robbie.

"I got Harley Quinn through the New 52 version," Ayer said, "but then I really started going, 'OK, what's this character?' Then you get absorbed in her stand-alone things and then you get into her origins and her relationship with Joker. Defining that, it's salt and pepper. You have to have one thought with the other."

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But that's not to say he settled on Harley solely because of her connection to the Clown Prince of Crime.

"No, I wanted Harley. She's freaking cool," Ayer said. "She represents so many dichotomies in today's world where everything is so sensitive and you can't talk about anything or represent anything and you can't do anything. She doesn't care. She transcends everything. That's what is so fascinating about her. She's so many things, and such a powerful woman who is living life on her own terms and so honestly in the moment. And, a person who has an incredible joy in the moment. It's great to be able to work with that character. Margot is kicking her out of the park. Unbelievable. She's doing her own stunts, too. I've never seen that. Incredible."

Opening Aug. 5, "Suicide Squad" also stars Will Smith, Jared Leto, Joel Kinnaman, Viola Davis, Jai Courtney, Jay Hernandez, Adewale Akinnuoye-Agbaje, Ike Barinholtz, Scott Eastwood and Cara Delevingne.