Nathan Fillion

“Something I see in the very first episode — the very first scene we shot — there’s a playfulness that’s come back to Castle,” Nathan Fillion says, reflecting on the start of tonight’s fifth season.

And after a fourth season that had more than it’s fair share of trials for the beloved characters on the ABC hit — Beckett with her post-shooting PTSD and Castle with mounting frustrations toward his partner and friend — it’s time to give the characters and fans a chance to see this pair enjoying some happier times. Luckily, the end of season 4 set up exactly that, by finally putting Castle and Beckett in a romantic relationship together.

So what awaits fans? For that, EW turned to star Nathan Fillion.

ENTERTAINMENT WEEKLY: In the past, you’ve had some doubts about getting Castle and Beckett together. Has that changed?

NATHAN FILLION: Yes, I have never been a proponent of these two getting together because I’ve always seen it as an ending. But two things: First, I think our writers have always been good at designing circumstances that keep them a part realistically. They’re never on the same page at the same time. It’s always in a reality-based way. However, I’m finding now that seeing [them getting together] as an ending has been a folly on my part. This has actually — the way the writers are treating it now — they’re treating it as if the first four seasons have been a protracted beginning. Now we can finally start the show. So it’s all been a very long, protracted beginning and now we can start the show.

Tell me about Castle’s reaction to hooking up with Beckett.

You know, Castle’s the kind of guy who always got what he wanted. He got success early on as a young man starting to write, success started coming easy to him. He’s been very successful throughout his life. He’s made a lot of money, and when he wants something, he gets it. And Beckett has been one of those things that he has not been able to get. She was hard to get. He really, really had to work at that. And now that he’s got her, he’s happy. He’s quite happy. He enjoyed the chase, but he’s happy now.

Does Beckett return that feeling or have hesitations?

You know what? The way it panned out, I had wondered if she would still have difficulty with being emotionally unavailable when we came back for season 5. That’s always been her thing. She’s never been emotionally available and when she was, it was the wrong time. At the end of season 4, she had an epiphany. She finally hit a wall and something had to happen. Now that wall has come down, and she’s really in it. She’s now open. It’s nice to see that her character has made that stride.

Speaking of Alexis — does she know?

I don’t want to spoil it. We’re going to find out in the first episode how they’re going to deal with that.

Well, we know it has to stay a secret at work because of rules about dating co-workers — and partners, for that matter.

It’s their preference to keep it secret from everyone for the very first bit at least. It’s going to be precious to them and them only. They’re the only ones on the inside and no one is going to know in the beginning. It’s a little bit sacred. They can enjoy on their own without anyone’s opinion about it.

Not to mention, when the season begins, Beckett isn’t even employed, technically.

Yeah. She’s a hobo — a dirty bum.

[Laughs] What IS Castle’s reaction to Beckett quitting?

You know, Castle has always been a big supporter of Beckett. It doesn’t matter what she does. He’s there to back her up. So I think that’s a great thing to have in a relationship — someone who will back you up no matter what they think about your decisions.

As far as them being a couple, do you see this going slow? Or do you see them immediately thinking about the next step?

Oh my gosh, they only just got together! I think they’re going to have to wallow in that for a minute or two before they start thinking about the next step. They only just got in bed. Slow down, Sandra. Slow down!

Do you see them eventually getting married or having a baby? Bones did it…

I would say — my humble opinion, with my own eyes seeing into the future — I would say them getting married would be a really lovely series finale. Years from now.

Speaking of which, how many more seasons do you think we have here? The show will obviously go on 15 years, but…

Obviously. [Laughs] Honestly, I’ve always been a big fan of the way the English did their series. They come out strong with fantastic shows, do two seasons then boom they’re gone. Two [seasons], maybe three, sometimes 4, then they’re done. Twenty years later, they pick it up again. I like the idea of a strong finish. We’ve seen too many shows die out and peter out. Being in the industry, I’ve seen many situations where someone will get the call from the network where they say ‘You guys have 5 episodes to wrap it up.’ Then all your long-term story arcs gotta get wrapped up in five episodes because that’s how many episodes you got left. I would hate to see that happen to Castle. I would rather it finish strong.

Lastly, give me a taste of how steamy the beginning of this season is. I mean, we last saw them hot and heavy. Will there be more of that?

We are going to start season 5 a couple of hours after we left them in season 4. So we’re going to pretty much pick up where we left off and we’re going to see the aftermath. It’s not going to be two weeks later; it’s going a few hours later.

So…still hot?

Well, yeah. Geez, they just started dating. It’s that whole honeymoon phase, right?

Well, it’s been a while, which is why I live vicariously through them.

[Laughs]