<i>Castle</i> Castle

On Monday's episode of Castle (10/9c, ABC) Detective Beckett (Stana Katic) and Castle (Nathan Fillion) investigate the murder of a man who appears to have a double identity, a concept not unfamiliar to the show's creator, Andrew W. Marlowe.

Check out photos of the Castle cast

No, Marlowe doesn't lead a double life, but his show is increasingly a mix of cops-and-robbers procedural fun and good ol' family drama. "Both Nathan and Stana have settled into their roles, and ... we've had the opportunity to open up some of our supporting cast members," Marlowe tells TVGuide.com. "We think they're doing a terrific job creating a real family ensemble show. We're trying to be unlike other procedurals on TV; we're trying to bring some humor and character into procedural storytelling."At the center of it all is Fillion, who brings the funny both at the crime scene and at home with his teenage daughter (Molly Quinn

) and live-in mother (Susan Sullivan). "I think the fun thing about [the character of] Castle is you're kind of able to see him as a complete man," Marlowe says, "Sometimes when he's with Beckett, you have the 12-year-old juvenile Castle, and then when he's at home, you see him very much as a strong father figure. We like showing that multifaceted approach because in real life, none of us are one person. We all play a series of different roles, whether it's with our lover or our parents or our kids or our colleagues. To be able to do that only opens up the character."

Castle picked up for full second season

Marlowe's approach seems to be working. Debuting as a midseason replacement in early 2009, the show survived being on the bubble in May and has pulled strong enough numbers to earn a full Season 2 pickup. Marlowe gives much of the credit to his two stars, but he says he's excited to expand the story to supporting players such as Detectives Ryan (Seamus Dever) and Esposito (Jon Huertas)."We're bringing them more into the cases, giving them a little more to do," Marlowe says. "They're just doing terrific work and they've really popped. I think in the latter part of this season, we'll have an opportunity to see a little more of them in their private lives."Tamala Jones [Dr. Lanie Parish] has been a terrific role player, and I am looking for an episode to feature her with a medical mystery," Marlowe continues. "I'd like everybody to get a moment in the spotlight as we move forward. As the show goes on and as viewers are more familiar with all of our people, we feel like we have an opportunity to add to our storytelling by exploring those characters."

Castle: Is a Beckett-Castle kiss in the cards?

But don't look for Marlowe to abandon what he calls the engine of the show: the will-they-won't-they romantic tension between Castle and Beckett. "Audiences expect forward motion... [but] you never want to resolve something like that too quickly," Marlowe says. "In this sort of relationship, when the romantic tension is running high, the opposite side of the spark is that there could be misunderstandings and wedges driven between the people. So we want to keep it going as long as we feel like it can sustain, but we also need to grow the relationship so it doesn't feel like we're stuck in the same gear. That's the delicate dance moving forward."Marlowe is equally hesitant to wrap up the story of Beckett's mother's murder too quickly. "We do have an episode dealing with it coming up; there will be some significant movement in the case in that episode," Marlowe says. "It's so much a part of Beckett's character, this unresolved mystery, that we feel like resolving it too quickly would not be fair to her character. It's something that we will be developing over the next season or two until we get to the ultimate resolution."And it's the concern Marlowe has for his characters that he says drives him to make Castle unlike the rest of TV procedurals. "Some of those shows take themselves very, very seriously when they hang a line on a guy putting on sunglasses," Marlowe jokes. "But we want people to know that we're taking our cases and our people seriously."After a long day, I'm not sure I'm ready to delve into that darkness," Marlowe says. "There are a lot of people out there who do love the structure of the procedural, but don't want to go so far into the gutter. They want to have a good time and want to have characters to root for. We're giving people permission to have fun during the hour."