(CBR) Following a month-long hiatus coinciding with the Winter Olympics, "Marvel's Agents of S.H.I.E.L.D." is back with a new episode on ABC tonight, titled "T.A.H.I.T.I." That's not all that's new: The episode also sees the debut of veteran actor Bill Paxton as John Garrett, a S.H.I.E.L.D. field agent who has a long history with Phil Coulson (Clark Gregg).

One week later, Jaimie Alexander will guest star in her "Thor" and "Thor: The Dark World" role of Asgardian warrior Sif, representing one of the strongest unions yet between "Agents of S.H.I.E.L.D." and the Marvel Studios film franchise (beyond Marvel movie mainstay Gregg starring in the show, of course).

Paxton and Sif's appearances follow the recent revelation that Mike Peterson (J. August Richards) -- part of the show since the pilot -- is now the show's version of Deathlok, the most famous Marvel Comics character to be introduced on the show yet.

CBR News spoke with "Agents of S.H.I.E.L.D." executive producers and showrunners Maurissa Tancharoen and Jed Whedon about all of the above and more, including the May (Ming-Na Wen/Ward (Brett Dalton) relationship, the recent mysteries surrounding Sky (Chloe Bennet) and the show's early mixed reception from critics and fans.

CBR News: Maurissa, Jed, let's start with arrival in this week's episode of Bill Paxton as John Garrett -- is there anything more you can share at this point about the role he's going to be playing on the show?

Jed Whedon: We're never allowed to share anything. [Laughs] We're so well-trained at this point that when people ask us questions, we just close our mouths.

Maurissa Tancharoen: We close our mouths and our brains explode because we can't compute what we're allowed to say and what we're not allowed.

Whedon: We can say that his character's a lot of fun. In just initially talking about the character, his name came up of dream choices to play someone with this sort of attitude about S.H.I.E.L.D., as a contrast to Coulson. Coulson's always been the company man with a dry sense of humor, whereas Garrett's a guy who never wanted to wear the tie, never wanted to be behind a desk. He's in the field because he likes being in the field. He likes blowing things up.

Tancharoen: He likes getting his hands dirty.

Whedon: Their friendship and back-and-forth has been a real pleasure to write, and seeing Paxton do it every day -- we're having a blast.

Since he's on board for multiple episodes, what's it like dropping an actor like Bill Paxton into a show like this? How does it affect the dynamic of the episodes he's in?

Tancharoen: It's been a lovely surprise, because he just fits right in. It's really nice to see Clark have someone that he's sort of palling around with. Of course, there's the initial few days when everyone is very enamored with Paxton -- he's regaling us with all of his stories from being in every single movie ever known to man. [Laughs] Telling us how he's been killed by a Terminator, an Alien and a Predator. He's the only guy who can claim that title. [Editor's note: Lance Henriksen joined this club following 2004's "Alien vs. Predator."]

We definitely developed the part with him in mind, and then the day when he was actually on set playing the part, it just all fell into place and made complete sense. Bill Paxton is Bill Paxton, and brings what Paxton does to any role. It's really fun now in the room to break his stories and his dialogue, and it's really fun to see our characters play off of a guy who definitely has a distinct personality from the team we've established on the show. It's a nice contrast, as well as a nice source of tension at times. There's a lot of drama and comedy to be mined from the relationship we build with him.

Fans are fairly obsessed with seeing characters from the comic books on the show, and since John Garrett does have a history in the comics, how did you arrive at using that character specifically?

Whedon: The character came out organically. We knew we wanted someone to come into this episode, and we knew the niche we were trying to fill in terms of a character we wanted to have on our show. We talked about various people from the comic book universe that it could be, and Garrett was the right fit. He's got the attitude we were looking for, and he was on the list of people we could use. [Laughs]

Tancharoen: To just be blunt, there is a list of characters we can use, and his name was on there, and then he happened to serve the purpose we were looking for.

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