While the crime-solving duo of Richard Castle (Nathan Fillion) and Kate Beckett (Stana Katic) continue to play the will they/won't they game on ABC's "Castle," the murders themselves are also a huge draw for viewers since the unusual crimes routinely have multiple twists and turns before they're solved. Tonight's episode, for example, pays homage to "The X-Files" with a case involving a possible alien abduction that leads to murder. Singer/actor Lyle Lovett guests as a mysterious government agent while Lance Henrickson (who starred in "X-Files" creator Chris Carter's series "Millenium") appears, naturally, as an expert on alien abductions.

Our Jim Halterman spent some time on the set of "Castle" last month to chat about what else is store on the romantic side of things (hint - one couple will be hitting the sheets and it is not our leads) as well as how the writers carefully dole out the danger for our regulars including Castle, who technically is not a trained police officer.

First and foremost on the agenda is to ask about the romance of Castle and Beckett. It originally looked like the twosome might finally "go there" at the end of last season. In May's finale, Beckett was about to tell Castle she was ready to take a chance on being more than a crime fighting duo but the unexpected reappearance of Castle's ex-wife and their rekindled romance stopped that development cold in its tracks. Ironically in the current season, Castle's relationship seems to be hitting the skids while Beckett was recently revealed to have a new, sexy beau (Victor Webster).

Creator Andrew W. Marlowe, for one, thinks the off timing for the characters is a good thing. "I feel like if [Castle and Beckett are] both coming from the same place you're not creating obstacles for the relationship and as much as the audience wants to see these two characters together the point at which we choose to do that we know that a certain amount of tension is going to dissipate. We don't want to do that too soon but we also know that we don't want to jerk our audience around but I think there are ways of doing it where it's like the rhythm of life were two people who are perfect for each other don't recognize it right away."

Fillion shared that regardless of when or if Castle and Beckett get together, they're still bonded and, for now, work is what their relationship is about. "In replace of sex they have solving murders," he said from the loft set where Castle lives with his teenage daughter, Alexis (Molly Quinn). "The time when they're not fighting and they're actually getting along and they're starting to complete each others' sentences and all the pieces are starting to fit and they go "Ah, we know who our guy is!" That's when they get along best."

Katic, who told me earlier this year at Comic-Con that she doesn't think the two characters coming together necessarily means the tension and heat has to go away, said that fans may have to wait awhile before Beckett puts herself out there again for Castle. "She's always going to have feelings for him but she's kind of decided that he doesn't have feelings for her in that same way or maybe not in the way that she needs so she just brushed them aside... and decided that it's going to be a fabulous working relationship and she'll really enjoy that with him. In order for her to move forward and maybe test those bounds again I think it's going to take a really big break from Castle's end first."

One romantic coupling that is set to progress further than the Castle/Beckett relationship is that of Detective Javier Esposito (Jon Huertas) and Medical Examiner Lanie Parish (Tamala Jones). "There is a little surprise [coming up for] Esposito and Lanie," says Jones. "A little exchange. Esposito kind of gives Lanie the eye a little bit and it kind of throws her... it starts there and just grows." Jones also said that the fling between the characters will lead into an upcoming Lanie-centric episode that puts her supporting character front-and-center for an episode. Unsure of the exact details, Jones said Marlowe and the creative team "are very, very good about keeping secrets and not allowing us to have any idea of what we're going to be doing." But why pair up Lanie and Esposito as opposed to another combination of characters? Marlowe revealed that the idea came about in an unexpected way. "I think it started with the two actors just playing around on set and me seeing that there was something there that we could capitalize on in storytelling."

Romantic pairings aside, there are also crimes to be solved and that, of course, occasionally puts our characters in danger. Since Castle is really a writer of crime novels who has special privileges to shadow the police, how does Marlowe deal with him actually being put in danger at times when solving cases? "We know that we're walking a fine line with having a father who has a daughter putting himself in situations where he might be in harm's way so we try to shy away from that," Marlowe explained. "That being said, if you're choosing to do what Castle does and you're knocking on that door every now and then it's going to open and you have to deal with what's on the other side."

During the on-set chat with him, Marlowe did take time to confirm that we haven't seen the last of the story thread from the start of the series regarding Beckett's mother's murder, a story that pops up a few times every season on "Castle" and is truly the foundation why Beckett became a cop in the first place. "We are planning an episode that deals with Beckett's mother's murder probably in the January episodes," he said.

If the comic bantering that weaves itself through the more tense crime moments on the series seems familiar, Marlowe shared where his inspiration for the series came from. "I think it's no secret that 'Castle' and the central relationship evolved from things like 'The Thin Man' and all the great screwball comedies and the Tracy/Hepburn films," he said. "It is the work of the moment that is the foreplay and the attraction between the two of them."

During the set visit, the actors also seemed to have a plethora of ideas of where they'd like to see their characters go in upcoming episodes. Ruben Santiago-Hudson, who plays NYPD Captain Roy Montgomery, said that he'd love to see more of his backstory with Beckett come to light where he almost feels like a protective uncle to her. "I feel my character has a relationship with Beckett that's a little deeper than me being her captain." Jones would love to be involved with the casting of some of Lanie's family and would love to see actress Pam Grier play her mother.

Seamus Dever, who plays Detective Kevin Ryan, feels that there may be a reason why we don't know much about his character. "We've established that Ryan was in the narcotics division and we'd like to go into that world a little bit. It's not like we were born here on the set of the 12th precinct. We have pasts and we have people in our pasts and my family. I love that there is a reason that I never talk about my family except my older sister." Katic, for one, is hoping the fact that Beckett is dating a doctor who happens to ride motorcycles could lead to some more action packed scenes for her... and her stunt double. "Please God! I'd love that and my stunt double is one of the top motorcycle stunt people in Hollywood so I would love that a lot!"

At the end of the day, though, a television show is part of a business. Do the actors pay attention to the show's competition and ratings? Katic, for one, has a close friendship with Alex O'Loughlin, who happens to star in time slot rival "Hawaii Five-0," and has taken cause by ribbing him via text. "One of my first texts was 'Are you serious? You had to take the slot opposite mine?' Then we were up for this "Hot Cop" list for TV Guide and we were against each other so, of course, a little bit of teasing [went] in on that." Joking aside, though, Katic gets the ratings game. "It helps for the longevity of the show if it's doing well as far as ratings are concerned so it's always nice to know that people are watching and tuning in."

Asked about the most challenging thing about his role as Castle, Fillion answered bluntly, "It's not terribly challenging. This is easy work. We're not pushing the limits of television technology or breaking down any story taboo barrier. It's just coming from the heart and playing the characters. There's nothing terribly challenging about it. The challenge comes in with the hours that come into this. Trying to look fresh, trying to seem fresh after doing it 60 times."

"Castle" airs Mondays at 10:00/9:00c on ABC.