In "The Firefly," tonight's episode of Fringe, Christopher Lloyd guest stars as Roscoe Joyce, the keyboardist of madcap scientist Walter Bishop's favorite band back in the 1970s, as both attempt to find a way to communicate with each other. Lloyd and actor John Noble, who plays Walter on the series, spoke with Spinoff Online about the episode, working together, and Lloyd's inability to play the keyboards.

"The Firefly" takes place several years after Roscoe's band, Violet Sedan Chair, broke up, and his life has taken a turn for the worse; he's secluded himself in an old folks home, where the alternate universe craziness of Fringe comes looking for him. To prepare for the role, Lloyd focused mainly on the script. It "really gave so much information, y'know, and clues that hopefully I was able to follow them and make it happen," he explained. "My character is very introverted and distanced from anything. He's kind of pulled out and retreated from society and the things that happen in this parallel universe, he has a lot of trouble grasping exactly what's going on. It's a lot of fun to play that kind of bewilderment and make it believable and real."

Noble finds the alternate universe an exciting component of working on the series. "The great opportunity is that it has allowed the actors in our show to play doppelgangers -- slightly different versions of ourselves," he said. "It has been amazing for our set design people to be able to create a world just like ours, but slightly socially different."

Though entering into the dynamic of the cast (and their dual roles) could be daunting for an actor, Lloyd enjoyed his time with the ensemble, "It was just such a pleasure; everybody was very supportive and I really felt I was being included."

While Roscoe's band is an established part of Fringe lore, this episode marks Walter's first encounter with any members directly. Asked if he was excited to have Lloyd play one of his character's musical heroes, Noble replied, "He is one of my heroes anyway, so when they said that Christopher Lloyd was coming on, it was like a dream come true." Having him play a member of Violet Sedan Chair was an added bonus. "We had an amazing time together," he continued. "These two old guys reminiscing and picking the music back up again, it was the best time."

Noble appears in most of Lloyd's scenes and says the work they did together is among his favorite from the series. "We had a lot of laughs. The common thread is trying to find the music again, because Chris's character has forgotten how to play the piano," he said. That search for the music plays into their attempts to communicate. "We go through this journey of bringing the music back to him and [the] thrill to Walter. This happens all the way through this very complicated episode, but it turns into pure joy in the lab."

Though actors will often take time before shooting to create the rapport seen on screen, Noble says the pace of shooting precluded that for himself and Lloyd: "Someone with Chris's depth of experience and ability probably makes it look easy, but I'm sure it's not [easy] to walk into an ensemble. There's no rehearsal and we really don't meet each other until we actually go on to do the scenes. That's pretty tough going."

"The two characters we play are from such vastly different worlds, and yet there seemed to be a common ground between them," added Lloyd. "When I come onto a show where I haven't met any actors, I try to zero in on the script and what's expected of the character I'm going to play and hopefully keep my focus on that and friendships develop from that."

Part of that development required Lloyd to mimic piano playing, but unlike Roscoe, Lloyd himself is not a pianist. Instead, the actor used a special prop to simulate playing. "They adapted a piano so I could pound on the keys without making any noise and it would play what they had written," he explained. His childhood also offered one other sense memory. "I grew up in a household where everybody was playing piano all the time, so I had the feeling of the kind of body movements that went with it."

Of course, it's not all music and discovery, as this episode also features an appearance by Michael Cerveris as the Observer. "To have Michael back in his 26th episode is fantastic. I have a wonderful scene with him myself," said Noble. Since the series pilot, Observers have been on the scene of incidents to offer ominous looks and words to the characters; more than that, they are part of the series' core mythology.

"One of the founding premises of Fringe is that because of the interference of an Observer, we ruptured the two universes," Noble explained. "I think what we've discovered is that if they do become hands-on at any stage, they can wreck the natural order of things ... it's interesting to have them back in again trying to put things right. At the end of the episode, the Observer has the last scene, and he says something incredibly telling. It just shows how much danger and drama there is ahead."

Although he declined to give a clue as to the Observer's final thoughts for the episode, Noble was willing to share a few items about his parallel universe counterpart, affectionately referred to as "Walternate." According to the actor, "At this stage, he seems just like this sort of nasty, cruel man. We will give you a lot more background on why he's like he is over the course of this season."

He also said the character will be humanized to a certain extent: "Behind that steel exterior, there are decisions that he makes that are very difficult. We've done some terrific scenes that don't soften him, but help to understand that he is, in fact, a man and not a machine."

Playing both versions of Walter, Noble hopes the characters will one day have a resolution. With that in mind, several upcoming episodes will focus on the alternate universe. "We can't resist the alternate universe," he continued. "Having created it, we have to go back there because of this huge conflict."

For Lloyd's part, although Roscoe is a one-off guest character, the actor himself is no stranger to TV. He was part of the ensemble of Taxi back in the late 1970s and produced shows like Fraiser. Asked if he would ever return to weekly television, he responded, "If the right part came along, a great team of writers, and a cast and director with a character that I love doing, I would jump on it. It doesn't come up often."

Lloyd is perhaps best known for his role in the Back to the Future films as Doctor Emmett Brown. Asked why he keeps coming back to science fiction roles, he responded, "I don't know exactly how I end up with some of these roles. It mystifies me sometimes, but I am a fan of sci-fi. I love being taken into a strange world and when it's told with imagination and credibility, I love being taken on that trip. I always have."

Fringe returns to Fox tonight (January 21, 2011) in its all-new Friday at 9/8 PM central timeslot. Tune into Spinoff Online after the episode for our weekly recap!