In the DC Comics source material, the Joker and Harley Quinn enjoy a classic fairy tale romance. Arkham Asylum psychiatrist meets homicidal patient. Girl falls for lunatic. Girl adopts Harley Quinn identity, becomes Joker's sidekick and turns to a life of crime. Their twisted dynamic is a "key element" in the big screen adaptation of Warner Bros. and DC Films' "Suicide Squad," written and directed by David Ayer.

RELATED: Harley Quinn "Transcends Everything," "Suicide Squad" Director Explains

On the Toronto set of the upcoming feature film, producers Richard Suckle and Andy Horwitz held court in their own "Batcave," a room full of photographs, conceptual art and plot secrets for the movie. The dynamic duo spoke to press including CBR News about Joker's tattoos, Jared Leto's preparation for the iconic role, Joker's history with Harley Quinn and Mr. J's crazy set of wheels.

Richard Suckle: We want to take you through the [movie] lineup, starting with the first guy who's not really a member of Suicide Squad. I don't mean "not really," he's not a member of the Suicide Squad.

Andy Horwitz: No, he's not. But this was our first image that we released of Joker. Jared [Leto] has been doing some amazing transformative work in this movie. I think his look is very different. We had to obviously do something different from the people before, and I think now that you guys got to see the trailer, you got a little slice of what he is in the movie and how he acts. The look took a lot of time to zero in on and dial in. He's got his signature items of course. He's got his pistol that he uses throughout the movie. Tattoos are obviously a big part of his character and I think his tattoo that you guys see down here will be a very, very fun thing in the movie when he decides to put his hand in front of his face and create his iconic smile. He's got his ring that he makes people look at and kiss.

Suckle: The tattoos were a big part of the design of the character. You'll see over there a number of different designs, things that aren't just exclusive to the Joker, but other characters. David [Ayer] found a really fantastically talented local tattoo artist, a guy by the name of Rob Coutts, who designed all those things and everything you see that's on Jared. There's a lot that did make it into the movie, but he was a real great addition and a real blessing for us to find him, because as I'm sure you guys already know tattoos play a role in a number of the characters, not just exclusive to the Joker.

Horwitz: Jared did a lot of work on his body as well. I think he spent a significant amount of time prepping before he got here, working out. He's a vegan, so it's obviously difficult at times to try to gain weight and gain muscle, but he figured out creative ways around it, how to do it, and really dove in headfirst as he usually does.

Suckle: It's great having him on set, because you feel the energy, not that there isn't good energy on the set when he's not here, but there is an extra sort of -- it's like taking the volume control and turning it up a couple notches. The character is so unpredictable, and Jared is so in character and so immersed in his role, not that the others aren't of course, but he really goes to a place that is full immersion. You can have conversations with him and you're having conversations with him as the Joker, which can be surreal to a certain extent as a producer.

Is it terrifying?

Horwitz: It's intimidating.

Suckle: I don't know terrifying, it's... it's a lot of things. It's exciting, it's fun.

It's like playing improv.

Suckle: It's a little bit [like that]. It takes a little while to get used to. I've never had that happen before. And especially because, you know, it's such an iconic character, and there have been versions of the character that have preceded him. Terrifying, no. It definitely keeps on you on edge, let's put it that way. I think that's probably the best way I would put it.

Suckle: I'm sure you guys don't know who the next person is now.

Horwitz: Harley Quinn. She stole the show in the trailer. It feels like she kind of stole the show.

A little bit.

Horwitz: Yes, that's her. Margot [Robbie] has just been doing an incredible job with Harley, blowing us away every single day on set with what she's willing to do and what she can do. I think we've taken some liberties with the creative with the character, and obviously had some fun with her, but of course gave you some of the iconic stuff that you always know about her.

Her goodnight bat is a big part of the movie. She carries it for most of it. We created a special gun for her, which is her love/hate gun that she carries around.

Is there an established history between Harley Quinn and Joker when the film starts?

Suckle: Look, that's something I'd rather not say. I think the best thing would be for you guys to be surprised about how that plays out, or how it doesn't play out. One of the things I found the most challenging about her is because she's so iconic -- and I think she's become the most popular, if not successful female character in the DC world -- is she has so many iconic looks that we really had a challenge. You have so many different ways in which you could dress her and it was almost sad to actually have to say, "As much we want her to be wearing the one-piece suit, that it's not really right for what we're doing in this movie," but we designed it. She put it on. Just going through her hair, makeup and wardrobe test was a real treat. We tried so many different things, and so many different things that would be iconic, that hopefully will live in other films if we're lucky enough to make other films.

Horwitz: This is our tattoo board, which is obviously separated in Deadshot tattoos, Joker tattoos, Harley tattoos and Diablo tattoos.

Suckle: I don't think it's a surprise to say that the Joker and Harley relationship, and a good portion of the story, is very important in this film, so you can draw from what you want. But, the Joker/Harley relationship is key and it's something that is very important in this movie in addition to the actual Suicide Squad themselves and the mission they're going on.

Horwitz: Of course, we have Mr. J's ride, too.

Not a bad set of wheels.

Suckle: One of the cool things about the Joker that we talk about is David's take on him is he's a businessman. He's crazy, and he kills people, but he's super right. He's running a business. If you could imagine the head of any successful corporation, he runs his business that way. He just happens to be a psychopath. He's very, very conscientious of his business and he's also very conscientious of the way he dresses. Style is a really big part of this Joker.

"Suicide Squad" arrives in theaters August 5, 2016. Stay tuned to CBR News for more on the film.