Pour yourselves some Mudders Milk, Firefly fans, because we're going to have a little Jayne Day celebration tonight on Castle.
That's right: Adam Baldwin, who played Jayne Cobb opposite Nathan Fillion's Captain Mal on Joss Whedon's short-lived (14 episodes and a movie, Serenity) cult fave guests tonight as Detective Ethan Slaughter—and Castle's new partner.
Read on to hear what Baldwin told us about their Whedonesque reunion—and how Beckett (Stana Katic) reacts to her competition…
"It's like slipping into an old, comfortable beat-up brown coat," Baldwin told us about his reunion with Fillion, aka Captain Tightpants. "Chuck (Baldwin played NSA Agent John Casey) had finished so I was free. It is a show [where I'm] working with Nathan and the character's this rogue gang unit cop who has unorthodox methods, so I thought, Perfect, perfect fit. Do I have to shave? They're like, 'Please don't shave.' Yes! Winning."
Slaughter and Castle "come together for selfish reasons," he said about their characters' partnership, adding, "I think Castle does enjoy being brought along to some of the heroics." As for Beckett's reaction, Baldwin joked, "Beckett appreciates Slaughter's rogue good looks and fashion sense, but she's a by-the-book kind of cop, and Slaughter bends those rules so there's a bit of tension there, too."
Any chance we'll see a return of Slaughter's rogue character—and good looks—to Castle? "Well, he doesn't die," Baldwin mused, "and he doesn't do anything that's completely morally reprehensible to make him evil."
Whedonites will also appreciate the Firefly Easter eggs in tonight's episode: "There are a couple of winks and nods for some of the Firefly fans out there," Baldwin promises. "Nothing too un-subtle," he deadpanned, "maybe just a two-by-four to the back of the neck."
Meanwhile, we'll see another Whedon alumni appear in Castle's May 7 season finale—Dollhouse's Tahmoh Penikett, in a possible recurring role.
Castle airs on ABC Monday nights at 10 p.m.
So fans, what say you about the Whedonverse colliding on Castle? What sort of Firefly Easter eggs are you hoping to see tonight? Steer the Serenity ship down to the comments and weigh in!