Justin Theroux is an actor, a director, a screenwriter and Jennifer Aniston's boyfriend. Sorry Justin, I had to include that! His recent writing credits include Rock of Ages, Iron Man 2 and Tropic Thunder. Justin branched out and wrote his first musical screenplay when he penned Rock of Ages.

Rock of Ages "flopped" at the box office opening week, but everyone who worked on the film had a great time. Justin's already so successful, we don't think he's losing any sleep over it. At a Los Angeles press junket, Justin spoke to POTP about growing up listening to '80s music, working with Alec Baldwin and Russell Brand, and why he changed so much of the original plot for his film adaptation.
POTP: How was the practice of converting the play into a movie?
Justin: There's things you can do obviously in film that you can't do on a stage that are a little more three dimensional. In a movie, just because of the nature of how close the lens gets to people, you have to ground characters a little more and make them a little more real. You can also get away with more subtle jokes and subtle humor. You can proximate them on stage but you can't execute them.
POTP: Did your background as an actor help with writing the script?
Justin: For sure, yeah. I'm very sensitive to when I'm writing terrible dialogue for someone. A lot of times when I'm writing, I'm sort of shifting between half performing it and half writing it to see that I'm not saddling someone with ridiculous amounts of exposition, or constructing a joke… the back and forth between two [people], knowing the rhythm of that, being able to mimic a little bit.
POTP: It's interesting how special this music is to a lot of people.
Justin: Ya. It's crazy. I remember I was making out with a girl behind a basketball court listening to [a song], putting my hand up her shirt… Music is obviously one of those things that's so nostalgic. You can hear a song and snap back to that moment in your life. It brings you right back to whatever that is and that's usually, for the most part, a happy feeling [laughs].
POTP: Was choosing the songs for the movie a challenge and making them fit the plot?
Justin: The great thing about musicals is that the songs are the emotional center of the scene. That's a big thing off your plate. That's the pillar of the house, so really you're just trying to write funny stuff and trying to sharpen the characters and just get them to the song. A lot of times the end of the scene is when the song ends. It was criminally fun. So much of it, the song does the work for you.
POTP: How much fun did you have writing for Alec and Russell?
Justin: Russell and Alec are both great comedy improvers. You can write them all the way up to the moment that they step on set and they'll go further and have more fun with it. I'm not precious about my writing and so I'm happy to let them have fun with it. I love working on ensemble stuff because you get to hop between so many voices. And when you know who is going to be cast, it's an extra gift, capitalizing on their strengths.
POTP: How often when you're writing do you know the cast ahead of time? It seems like a rare thing.
Justin: I've been lucky. Most of the things I work on, I'll write blind and then the cast starts to get set and then you'll write to your cast. You want their input. For the most part I've been really blessed and I've been able to work with people who can do pretty much whatever you write.
POTP: What was Alec Baldwin's comfort level when it came to singing?
Justin: You'd have to ask him, but I think he was pretty comfortable. He makes fun of his own voice, but it's kind of funny.
POTP: How did you come to make large dramatic changes to the plot?
Justin: I think it was trying to identify what the audience wants to feel when they walk out of the theater. A lot of it came from meeting the actors. Tom's so smart, so grounded in reality. He treats it like he's playing Hamlet! One of the things we came up with is, he's become so famous and breathes such rarified air that no one tells him he's wrong. Stacee Jaxx didn't have the faculties to do that. Finally someone speaks truth to him in this article… To me it's a more satisfying arc for him. We took great care making sure every character had a resolve.