DC's next original animated movie showcases the DC Universe's Golden Age in Justice Society: World War II as the classic heroes band together to defend their world from the Third Reich. With iconic characters like Wonder Woman and the Golden Age Flash Jay Garrick leading the charge, the Justice Society is surprised by the sudden appearance of a displaced Barry Allen as he accidentally runs headfirst into the global conflict, with the war escalating to even more devastating proportions.

In an exclusive interview with CBR, screenwriter Meghan Fitzmartin (Supernatural) talks about what characters she enjoyed writing the most in the film, expressed her lifelong love of DC and getting to make her feature-length screenwriting debut with this movie.

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After working on DC Super Hero Girls, what is so rich about diving headfirst in the Golden Age, with the Justice Society, as a storyteller?

Meghan Fitzmartin: It's intertwined with being a storyteller and also just growing up in comics. It was part of my DNA anyway but being able to flex that muscle in a different type of way was just so much fun because it's another piece of my heart, DC Super Hero Girls are much more modern. And being able to pull out the Golden Age Justice Society and flex that muscle was another one of my favorite things, it was great!

After writing episodic content, you've got the full creative canvas of a feature film with this. What was it like being able to take advantage of that much real estate and scope with co-writer Jeremy Adams?

Fitzmartin: It was so much fun. It was more fun than it had any right to be! Sometimes I had to [remember] we're doing a job and not just me shooting the shit with my friend, we had to do this thing. It was amazing, the dream scenario. Working with Jeremy is a dream, I've been doing it for a while, and being able to riff off of each other and build off of each other was great. And being in a feature is cool because you get so much more real estate and so much more story and we packed so much into this. I'm still surprised we got in as much as we did.

With this featuring an ensemble cast of so many DC icons, which character caught you by surprise as you were developing their role and voice?

Fitzmartin: I knew that I would love Diana. I knew that I would have fun with Hourman, but Black Canary was the easiest one to write, I think, and so much fun; there was so much joy in writing Black Canary. I had an idea that I would like her, the way we put her in the story, but those [character moments] were breezes in the script. Any time she came in with a quip, I was like, "Oh, I love you!"

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With DC having such a deep bench of Golden Age heroes, like the Seven Soldiers of Victory and the rest of the JSA not appearing in the film, was there any character you wanted to include that didn't make the cut?

Fitzmartin: Yeah, the frustrating thing is when you're working with something with so much history like the JSA is that there are so many characters that you can pull from. It sucks that we're limited to just having the amount that we have because otherwise, it would be an unwatchable film; you wouldn't be able to hang out with everybody in any meaningful way. It was tough because there were so many that we talked about that we couldn't really figure out a way to wedge them in there because then it wouldn't be a fun story. With too many characters wedged into a story, it immediately takes you out of the story that we were trying to tell. So, at the end of the day, I love the team that we have and I'm glad that it works so well. We did go through this process of holding everybody up and going, "Alright, let's kill our darlings and figure it out!" [Laughs]

As somebody that has written DC characters for television, now film and, recently, comics with Future State, what is it about DC that you find so appealing as a fan and a writer?

Fitzmartin: Do you have an hour and a half for me to wax poetic about my love for DC? [Laughs] I grew up with this, DC is so much of my home comics and so, even though this is my first feature film, it felt like coming home with these characters and being able to play in this world that I not only grew up in but it raised me. So [many] of these characters have imprinted on my heart and have made me be the person that I am with the set of moral values that I learned from these characters. It feels like some sort of Ouroboros eating its tail!

How was the experience writing Future State: Robin?

Fitzmartin: Amazing, absolutely amazing. My editors were a dream to work with and it was so much fun. They brought me in on the Bat-Family which made me feel so honored and with a weight on my shoulders like, "You're giving me Tim [Drake]? My friend Tim?" It was just such a dream. I was so excited.

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What are you proud of in Justice Society: World War II?

Fitzmartin: I'm proud that we stuck to the theme that who knew would be so incredibly cogent during this, the time of Our Lord Quarantine: being able to say that being human matters and you matter and to do the best that you can. Steve [Trevor's] whole arc is extremely important to me, just how he lives and how he doesn't look at himself as weak and doesn't look at himself as being less useful because he knows he still has work to do and responsibilities. And think that's particularly important in this day and age. We work to love each other. We work to understand and be there for another in these times of hardship.

Is there any particular moment you're really happy and proud of being able to point out in the film as being something that represents you bringing your own voice to the movie?

Fitzmartin: That's extremely hard but I think I'm proud of Wonder Woman coming in and just kicking so much Nazi ass in the very beginning. Obviously, it's a collaboration and everybody put in their best work but being able to just look at how cool she is as she's kicking ass and taking names, that's awesome! I like that I did that.

Produced by Warner Bros. Animation, DC and Warner Bros. Home Entertainment, Justice Society: World War II stars Stana Katic as Wonder Woman, Matt Bomer as The Flash, Elysia Rotaru as Black Canary, Chris Diamantopoulos as Steve Trevor, Omid Abtahi as Hawkman, Matthew Mercer as Hourman, Armen Taylor as Jay Garrick, Liam McIntyre as Aquaman, Ashleigh LaThrop as Iris West, Geoffrey Arend as Charles Halstead/Advisor, Keith Ferguson as Dr. Fate and Darin De Paul as Roosevelt. The film will be released digitally on April 27 and on 4K UHD and Blu-ray on May 11.

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