After solving crimes as a mystery writer and leading some Browncoats, Nathan Fillion takes on his next challenge…being Green Lantern again in a new DC Justice League animated movie.

Justice League: The Flashpoint Paradox is available this week from Warner Brothers Home Entertainment. Based on the “Flashpoint” crossover from two years ago, the Flash thinks he has stopped a plot by time-traveling villain Professor Zoom. When he wakes up the next morning, the world is very different: someone else is Batman, Aquaman and Wonder Woman are literally in a war against each other, and Hal Jordan is involved in the battle… but not as Green Lantern. The Flash has to convince Alternate Batman to help him restore the original timeline, but the real solution won’t be that easy to reach.

It’s actually FIllion’s third DC animated movie as Hal Jordan/Green Lantern. He admits doing animation is much different than acting on Castle. “I can’t enjoy in the same way. When I’m watching something I’ve done,” he says, “in my mind I’m thinking about the work and the day that was all kind of behind that. It’s hard for me to be wrapped up in the story of something I was present for filming. It’s a little more difficult. However, in the animation process, you only do the voice in little bits, so when you’re actually watching the movie, the whole thing’s a surprise, really, because you don’t have anything visual to go by.”

He also approaches the role as a fan who now gets to be part of the comic book story. “I am now in the company of incredible actors, of whom I’m very fond of their work, some of them have become friends of mine,” he says. “Dana (Delany, who plays Lois Lane), I think I was a fan of hers just before I met her, and then we worked together a number of times, and now were friends, and now we’re working together on this as well. So now it’s come full circle on that one.” (note: Delany was in a couple of episodes of Castle in 2010).  He also talks about how he and Sam Daly (who voices Superman, just like his dad, Tim Daly) recreated their roles on Sam’s web series. “I like the company I’m in, “ Fillion says, “I like it.”

Fillion says his first movie as Green Lantern, Emerald Knights, was the easiest of the three because it was just reading in a calm tone. The second movie, Justice League: Doom, was different. “It’s the yelling. It’s the grunts, it’s the groans, it’s the impacts,” he says, “ those things what make you walk away going, ‘ahem, this voice work, I thought it’d be easier.’” Actually, he says this movie was easier because it was a smaller role.

Although he’s a popular actor among sci-fi and genre fans, he does some fannish things, too, like wear a t-shirt with painting of himself as Malcom Reynolds from Firefly. “Some people might think that’s narcissistic, I call it meta,” he explained. He did admit he has also used a Green Lantern shirt and wallet and Flash (the character) underwear.

Justice League: The Flashpoint Paradox is now available at Amazon and other retailers.