Nathan Fillion and Stana Katic, <i>Castle</i> Nathan Fillion and Stana Katic, Castle

[WARNING: The following story contains major spoilers from the Season 3 finale of Castle. Read at your own risk.]

Castle's third season went out with a bang. More than one, actually.

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So will you be adding a new boss at the precinct next season?

Marlowe: That's one of the opportunities we're looking to take. Everybody's getting along really well in the precinct, and we think there can be a little more conflict. We think it's interesting to grow Beckett and Castle by having somebody who may not look as favorably on Beckett as the Captain did or may not look as favorably on the Castle-Beckett relationship. That's all stuff we're plotting out for next year as we speak.

The finale also reveals that there's still a mystery man out there connected to Johanna Beckett's murder.
Marlowe: We have a great concept of how we want to follow that up in the next couple of seasons. That's going to be vital in some decisions I'm making going into next season.  We foreshadowed it a bit with Castle having to protect Beckett from herself at the end of the episode. Next season, with Castle knowing somebody is out there, [Beckett] becomes his responsibility. It changes the nature of their relationship and makes it significantly more interesting, especially given what happens the last 10 seconds of the show.

Indeed. Let's talk about that cliff-hanger. Are you prepared for the hate mail?
Marlowe: I do have an expectation that certain fans are going to be really, really frustrated. We have really tremendous, loyal fans and to make them wait all those months I think is going to be really frustrating to them. Hopefully people will be interested to see how we deal with it next year.  I do think, for the relationship fans, having Castle admit his feelings to Beckett is a great moment for them.

Did Beckett hear and understand Castle say "I love you" before she went unconscious?
Marlowe: I think in that moment she does. I know exactly how I'm dealing with it next season, but it would be unfair to the experience of the audience to tell them right now. 

What can you say about that relationship moving forward?
Marlowe: I think people will be frustrated until I do the next set of reveals at midseason. My feeling about TV audiences is that they love to be frustrated and then fulfilled. What we're telling here is a great love story, and great love stories take a long time to resolve. Feelings ebb and flow, relationships are complicated, timing is wrong. I do know where I want to end up with these people. I know what the resolution is between them but there's a lot of great storytelling between now and then.

Are you concerned with dragging it too long and losing viewer interest? You recently commented about Bones doing just that.
Marlowe: When I express some concerns about models of the other shows, it's when the relationship becomes stagnant. When there is no movement, there is no growth and the characters start to feel like brother and sister because they lose the spark. My goal is to not lose the spark, and I know that's a challenge when you keep people apart for a long time. Keeping them apart can be frustrating, but I also feel like moments at the end of the swimmer episode are enormously gratifying because of everything that's come before. The hero's journey is about going through all sorts of difficulty to obtain your prize and having little victories along the way. My hope is that at the end of the day, it feels like a hero's journey.

Will there at least be some payoff to Castle's admission of love?
During Season 4 there will be some payoff to what he said in that moment. It's not going to necessarily come the way the fans like. And I'm sure some of them will feel like I've skirted the issue initially and then come to realize that I've dealt with it in an interesting character way. The questions are going to be answered. I think people felt like we dropped the kiss or we dropped the freezing together, but it was always my intention to bring it up as a relationship issue [in the finale]. Hopefully people will be interested to see how we deal with it next year, and how we overcome the argument they've had in the middle of this episode. The issue of "Why aren't we talking about this? Why aren't we confronting it?"

Is Beckett's boyfriend Josh (Victor Webster) still a possible obstacle?
Marlowe: He's still out there, and he's somebody we're going to have to deal with. He's an element moving forward and it'll be interesting to see how that functions.

What's going to be the driving force in Season 4?
Marlowe: There's going to be a real push and pull between Beckett and Castle. Beckett's going to want to look into [this new mystery man] and Castle's going to have very specific reasons why he doesn't want her to. He'll end up with a little more information than she has, and he can't be honest with her about it. It's going to cause a complexity in their relationship that's going to be interesting.

What did you think of the finale? Were you shocked by the Captain's death? Are you excited that Castle admitted his feelings? Share all your thoughts in the comments.