Appropriate for an ensemble film, the cast of "Suicide Squad" seems to have bonded into a true unit over the course of filming the upcoming Warner Bros./DC Comics film. Not only did they all bond over Jared Leto's interesting gifts, they all got tattoos to mark their experience. During a press conference promoting the supervillain team-up film, the "Suicide Squad" cast talked more about the lengths director David Ayer had them go to to become a tight-knit group.

"David Ayer has a very interesting process of getting actors into their characters," said Will Smith, who plays the master marksman Deadshot. "Manipulation, domination, torture... [Laughs] So we all got in a room and he had it essentially much more like therapy than it was a character creation. We sat and talked about our lives and we got really close, [shared] our triumphs and tribulations and trials and then at the most opportune moment -- Joel [Kinnaman] described it best -- [Ayer] would completely betray us [Laughs]."

"It's a process, it's like a gymnasium for acting is the way I look at it," said Ayer. "I needed these guys to feel like best friends on camera, and when you're with your best friend, you share secrets. You talk about your inner life. There's a way you talk to a really close friend. I wanted them to have that energy, and the fastest way to get there was to have them beat the hell out of each other, share their secrets."

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"That's what friends do," added Margot Robbie, who plays Harley Quinn. The Joker himself, Jared Leto, dryly added, "That's also how you start a cult."

The bonding wasn't just emotional in nature; the cast actually did "beat the hell out of each other," as Ayer said. "David was a champ," said Adam Beach, who plays Squad member Slipknot. "He'd show up, train with us, beat us up. There was this moment when he was sparring with Karen [Fukuhara], and she got it in the nose."

"After he punched me in the face, he said, 'You gotta block your face Karen,'" said Fukuhara with a laugh. Adewale Akinnuoye-Agbaje jumped in and said that Fukuhara, who plays Katana, then took any frustrations she had out on him during their sparring session. "[Ayer] made me push so many weights and get big, and when I got to the size for Killer Croc and I'm thinking I was ready, he said, 'Now you gotta fight Karen,'" recalled Akinnuoye-Agbaje. "And look at the size of her -- but she beat the crap outta Croc."

"I could go all out because Adewale's so big and strong," said Fukuhara. "I could just punch away."

But all the physical exertion on set wasn't without a cost -- even if some of the injuries came during moments of relative calm. "When you're 47, no injuries are mild injuries anymore," joked Smith. "I tore my calf a couple weeks in, and it what's terrible is, you do it doing nothing. I wasn't doing anything. We're sparring and I step back to throw a shot, and my calf popped. You can hear it. People could hear it, and everybody's like, 'Oh, that's not good. Whatever that sound was, that's not a good sound.'"

Kinnaman added that he also had the "exact same" injury during filming. "I was just trying to show sympathy," he joked.

Robbie also received a few injuries, and her Harley Quinn outfit didn't help. "I had less layers to hide padding and stuff doing stunts, so that made it a little painful," said Robbie. "I thought I broke my rib at one point, but I actually just tore the muscles off the rib instead of breaking it. But it was fine, it was towards the end."

Co-star Jai Courtney pointed out one stunt involving Robbie jumping off of a helicopter that caused the actress to wince. "That hurt so much," she recalled. "You got up, knees raw, arms bleeding," said Courtney.

"The emotional stuff was definitely more difficult," said Robbie. "Exposing my most vulnerable sides to everyone in the room who were strangers at that point was incredibly hard. Trying to figure out the dynamic between Harley and Joker and why she is so devoted to this guy that tries to kill her occasionally, I mean, it took me a while to get my head around. The physical side was more fun than challenging."

Directed by David Ayer and starring Will Smith, Margot Robbie, Jared Leto, Viola Davis and more, "Suicide Squad" opens on August 5.