One part "Moonlighting," one part "Rockford Files" and a dash of family angst a la "Brothers and Sisters" and you have the one hour romantic/crime drama "Castle," which returns for season two tonight on ABC. While many midseason shows came and went last season, "Castle" was one that beat the odds to gain another season and our Jim Halterman made sure to ask creator Andrew W. Marlowe why he thought viewers gravitated to the show and not others. Also during their chat, Marlowe talked about the off-the-charts chemistry between stars Nathan Fillion and Stana Katic (who play Richard Castle and Detective Kate Beckett) as well as how things work in the writers' room when balancing the various components that make up every episode of "Castle."

Jim Halterman: When you were creating the show and the characters what was your inspiration?

Andrew W. Marlowe: I was a fan of the old-fashioned murder mysteries on TV with the eccentric characters and we've seemed to enter the age of procedurals where it's really more about the evidence than the specifics of the case. I thought there was an opportunity to tell some great characters stories in that arena so I wanted to be able to blend the stuff I love, which has always been character storytelling, with more of the procedural elements. When I set out to create "Castle," I thought, "Let's do something that's leans a little bit more towards the stuff I loved growing up." You remember "Columbo" and you remember "Rockford" but you don't necessarily remember the cases as strongly because the characters were so very interesting. As a writer myself, going through those periods when I'm deep into it and I never get to leave my 10x10 room, I thought, "Wouldn't it be fun to actually get to go out into the universe and do some of the things that we were writing about?," and that's where the concept of Castle was born; a guy who is a writer that actually gets out into the world and use some of the things he's learned along the way.

JH: The chemistry between Nathan and Stana is the kind that any network dreams of. How did that come together?

AWM: We started with Nathan, who was the perfect guy for this role. I think the line between Nathan and Castle sometimes gets blurred. We interviewed a number of actresses. I think when we were casting it we brought in about 125 actresses and Nathan was very gracious to join us in the sessions because, really, it's all about the chemistry and it really is about the ability for these two people to sell the kind of love/hate/sparks fly relationship. We were very fortunate to have Nathan in the room and when Stana came in there was that chemistry and we just had our fingers crossed that it would be captured on film.

JH: How do you balance the crime, romance and family element equally without one taking over the others?

AWM: When a draft [of a script] comes in it's usually weighted towards one aspect or another and we just look to make sure we're telling a complete story. There are some episodes where the case will dominate and there are some episodes where it will be a little bit more character stuff but we try to keep it in that sweet zone in the middle where each element of the storytelling is contributing. I also think that the thing that we look to do is have the personal stories speak to what the main story is so it feels as if it's all a part of the whole.

JH: In the writer's room what comes first? The case of the week or the character stuff with Castle and Beckett? Where do you start?

AWM: The Castle/Beckett relationship... I think everyone understands that DNA. These are two characters who like each other but there are obstacles and for the fun of the show we have to maintain those obstacles. Oftentimes, since we're so familiar with those two characters, we start with the case and see what the case suggests in terms of a personal story that can fit into or around it. Then we look at the order of the cases so the personal stories end up laid out with the main cases relatively cleanly. Usually at the beginning of the season, it's a lot of people sitting down talking about the creative murders that they've heard about or thought of and whether it feels like a "Castle" case and whether there's an element of fun to be had or as much fun as you can have being respectful to the fact that we have a body and we have a victim's family and all that sort of stuff. But if there's something interesting and unusual about the case that our characters would be interested in... you have Detective Beckett, who is detective at the top of her game who isn't going to be as engaged with a run of the mill murder case. Then, you have a guy like Castle whose interest is, "What's the story of the case?" If it's a simple Jack shot Jill over Bill it's not going to be that interesting to him so we're always looking for cases where our characters can engage.

JH: How do you maintain the audience's hunger to want them together when we all know what can happen if that happens too soon?

AWM: It's early in the series and I think the characters will tell us where they need to be and what they need to do. I think life throws complications at relationships and that's a good guiding light for us. New people enter, old flames resurface and there's plenty going on to keep these two people at arms length. I think the characters are making the choices themselves. Beckett doesn't want to be one of his conquests and for Castle this is a woman who has challenged him in ways that other women haven't. I think that there's a fear on his part that going any further will ruin their relationship so I think they both feel like they can flirt and play with each other up to a line but at this point they're both scared to cross it. In the future, there will be many other complications; he'll date somebody, she'll date somebody, there will be missed opportunities, near misses. I think that as long as we're honest about the relationship with the audience and we're not fraudulent and trying to force it and manipulate our characters into a particular situation I think they'll be patient as long as we're also having fun.

JH: Is it safe to assume that the mystery behind Beckett's mother's murder isn't really going to go away even though she doesn't want Castle to pursue it any further?

AWM: It's something that is going to keep popping up. We don't want this show to feel serialized so it's certainly not going to be in every episode but we are going to deal with it and it is going to come up with certain particular cases and we'll get a little further down the field with it on occasion but it's not going to be something that will cast a huge shadow over the series. We want to be very friendly to the occasional viewers but also reward our loyal and longtime viewers.

JH: Is there going to be opportunity to explore more of the supporting characters this season?

AWM: I think we are very blessed with having a very strong supporting cast and we actually look forward to being able to explore them a bit more. Being a midseason show last year, we got 10 episodes under our belt and we felt like we were just starting to hit our stride and, of course, coming back this year we wanted to reintroduce ourselves to the audience. The first several episodes are focused on the Castle and Becket of it all but as we get into it, I think Jon Huertas, who plays Esposito is a tremendous actor and Seamus Dever, who plays Detective Ryan, is terrific and the two of them have a great chemistry together in their own right both in character and just as the actors waiting for someone to yell "action." I think that Ruben Santiago-Hudson is a tremendous actor and I'd like to see a bit more storytelling for him, as well and, of course, Susan Sullivan. We're all big fans of Molly Quinn who plays Castle's daughter. That character is coming into an interesting time in her life in that she's about to turn 16 and even being a good kid there are temptations and challenges... as a character she's very smart, got a good head on her shoulders but I think there will be times when she is challenged and that Castle is even more challenged by some of the stuff that she's going through.

JH: In the season premiere, Alexis talks to her father about her confusion over boys and relationships but what she says actually resonates with Castle's situation with Beckett. Was her character planned to be an insightful presence in Castle's life?

AWM: Absolutely. I view her as an old soul but there are times when she is absolutely her age and she needs emotional support. Castle is a very good father but there are times when she has to be a parent just because of the kind of guy that he is and I think when you grow up in that household with a grandmother (Sullivan) who is always vying for the spotlight and a father who is famous and enjoys being a little bit of a rogue, the way you rebel is by being smart and having a good head on your shoulders and being emotional mature. There are times when she's the emotionally mature one but then there are times when you're 15 or 16 and you're just starting to date and you're trying to figure out what life is all about that you need someone to lean on and in those situations her Dad is always there for her.

JH: "Castle" premiered this past spring around the same time as some other ABC dramas like "The Unusuals" and "Cupid" but "Castle" was the only one to get renewed. Any theories as to why your show caught on while the others did not?

AWM: Honestly, I think that we were in the right place at the right time on the right network. I think having the key emotional relationship between Becket and Castle that people could tune in to see every week while they were watching a procedural was helpful. "The Unusuals" was much more of an ensemble and there was a lot for the audience to track. I thought there were a number of great qualities about the show. I didn't really see "Cupid" so I can't comment on it. But I do think that shows like "The Mentalist" and the growing audience that we have for "Castle"... I think there is a feeling that the conventional procedurals - the "Law & Order"s and the "CSI"s - they keep going further into sensationalist areas to try to maintain their audience and there's a lot of darkness that comes out of those shows and the world is at a difficult place right now I think people want to come home and see something familiar that is a procedural but they also want to have fun along the way and we're hoping to provide them with the procedural elements that they're used to executed at a high level but also give them some of the character fun with some of those kinds of stories.

"Castle" debuts its second season tonight at 10:00/9:00c on ABC and the first season DVD is available tomorrow everywhere DVDs are sold.