It’s hard to believe that it has taken Castle four seasons to stage a Firefly reunion. But at least that reunion looks to be worth the wait — Adam Baldwin will guest star in this week’s episode, “Headhunters.”

Who will Baldwin play on Castle? What antics can the former Malcolm Reynolds and the former Jayne Cobb get up to when fighting crime in New York City? We talked to Adam Baldwin himself for the answers.

Baldwin, an actor well-known for his roles of Jayne Cobb on Firefly and John Casey on Chuck, will play Detective Ethan Slaughter on Castle. According to Baldwin, Slaughter is “a tough, colorful, kinda-rogue, gang-unit cop who runs into Castle while investigating a crime and decides to bring Castle along for some adventures and thrilling heroics.”

Baldwin hinted that Slaughter initially lets Castle tag along for “selfish reasons,” before the writer actually provides some help in solving part of the crime.

Want to see Slaughter in action? Click here to watch a video clip from “Headhunters.”

Ethan Slaughter is a little less on the straight-and-narrow than Kate Beckett, but Adam Baldwin was quick to point out that Slaughter isn’t any sort of villain. “Morally ambiguous? I don’t know,” he said. “He’s still trying to capture and imprison bad guys. There’s a fine line you can walk, and I think Slaughter just maybe tips over that line a bit.”

When asked about comparisons between Slaughter and Baldwin’s other characters of Casey and Jayne, the actor did admit that a certain grunting noise might be coming from the Castle detective. “That might just be a natural eminence from me in the gentle resting periods between lines,” Baldwin hinted. “I think a couple may escape.”

Click here to check out Castle photos from the “Headhunters” episode.

Baldwin’s guest-starring role on Castle marks his first on-screen reunion with Nathan Fillion since the 2005 Firefly movie, Serenity. This reunion, however, brings a very different dynamic between the two actors. When asked about having the chance to boss around Nathan Fillion’s character, Adam Baldwin was enthusiastic in his response. “I chewed the furniture with that! Any opportunity to put him in his place, it was great. It was returning the favor from the old days of Firefly and Serenity, when he would kick my ass,” Baldwin said. “[Fillion] just loved being able to be put in that position too.”

No matter who was kicking whose ass, Adam Baldwin had nothing but good things to say about his time working on Castle. “It was a joy. It was a reunion. Just like putting on a pair of old boots or a nice, warm coat,” he explained. “It’s the way it really should be in professional show business.” Baldwin had extra praise for Nathan Fillion, who he said “carries the show on his shoulders.”

There have been rumors that the Ethan Slaughter character could recur on Castle, but Baldwin would neither confirm nor deny them: “It’s above my pay grade to make that kind of decision, but I will say that you’ll love the character.”

What is in store for Adam Baldwin in the future? Other than a role he couldn’t yet talk about, Baldwin described his employment status as “at liberty.” “I’ll have to go play golf or something,” he joked. “Maybe I’ll never work again. But I’ve only been doing it for 30 years… So if this acting thing doesn’t work out, who knows? Maybe massage-therapy school? Lion taming?”

Whatever the future brings for Adam Baldwin, we will get to see him at least this one time on Castle. “Headhunters” airs on Monday, April 16 at 10pm on ABC.

Click here to check out the official ABC Castle website.

(Image courtesy of ABC, special thanks to Crystal Waters and Michele Palmieri-Colantriano for additional questions)

Laurel Brown

Senior Writer, BuddyTV

Laurel grew up in Mamaroneck, NY, Grosse Pointe, MI and Bellevue WA. She then went on to live in places like Boston, Tucson, Houston, Wales, Tanzania, Prince Edward Island and New York City before heading back to Seattle. Ever since early childhood, when she became addicted to The Muppet Show, Laurel has watched far too much TV. Current favorites include ChuckModern FamilySupernaturalMad Men and Community. Laurel received a BA in Astrophysics (yes, that is possible) from Colgate University and a PhD in Middle Eastern Studies and History of Science from Columbia University before she realized that television is much better than studying.