Was it Walter who addressed the crowd at Emerald City Comicon, or Walternate? Was it Astrid, or ... well, we'll get to her name in a minute.

The answer in both cases: neither. Fringe actors John Noble and Jasika Nicole were their own charming selves for an hour-long panel Saturday afternoon, opening up about their approach to their characters, their navigation of the alternate universes presented by the Fox series, and — to a limited extent — what fans can expect in a few upcoming episodes.

"We just finished an episode, and to be honest, it's the most unusual thing I've ever done," Noble told the near-capacity crowd. "When you see it, you go, 'What?'"

But true to form for a show steered by J.J. Abrams (Lost, Alias), the cast members had to observe a certain secrecy. "I can't really tell you much more than that," Noble concluded, "but when you see it, it's so interesting."

Fringe centers on a special government team that breakdowns in the fabric of the universe — singularities that allow elements of a parallel universe to invade this one, and vice versa. As resident mad scientist Walter Bishop, Noble plays a man whose own work contributed to these fractures. Nicole's character Astrid Farnsworth is an assistant to Walter who's also his greatest friend and caregiver.

Moderator Jackson Holtz, pop-culture writer for the Everett Herald newspaper, noted the universe shifts that Fringe characters must negotiate — sliding between parallel worlds and meeting versions of themselves who don't always share their views of right and wrong. Is that a challenge for an actor to keep track?

"I would say that for Astrid, and the alter-Astrid, its not difficult at all, because they are so polar opposites from each other," Nicole said. "You have the Astrid from this universe, who is really empathetic. She's kind and she has emotional attachments to everyone that she works with. Then you have your alter-Astrid, who is autistic and doesn't quite come equipped with the social graces that most people have."

As one audience member noted, she also doesn't have her own alt-world name, unlike the parallel versions of Agent Olivia Dunham ("Fauxlivia") and Walter Bishop ("Walternate").

Nicole had a suggestion: "'Kickasstrid?'"

Part of Walter's role is explaining the "fringe" science at play in each episode — string theory, bioelectric fields, protein modeling and so on. Noble said he tries to study up on current theoretical science, just so he has the grounding to get Walter's science-factional dialogue across to the audience.

"Generally, we try to make things that are theoretically possible happen in Fringe," he said. "... When you read that stuff, it just opens up the horizons for a show like Fringe forever. The material is really there in the world."

The actors revealed they're often allowed a role in the shaping of that material, even before they step in front of cameras. They sometimes suggest script changes in order to remain true to their characters, and they're listened to.

"If it's something that doesn't make sense for Walter, I get a bit edgy about that, and send long e-mails down to Los Angeles," Noble said. (The show is filmed in Vancouver, British Columbia.) "At the beginning of the year, I said, 'Walternate should have a mistress,'" he continued. "And they gave me one!"

When the show geared up for its musical episode "Brown Betty," the musical theater-trained Nicole realized she hadn't been given a song. Astrid wound up with a number from A Chorus Line.

Nicole is also an artist and illustrator, and spent part of ECCC selling artwork from the guest table she shared with Noble. "I've been getting into making comics for about the past four years," she said, "and the fact that I ended up on a sci-fi television show that brought me to comic cons was like a weird dream come true."

While refraining from too many specifics about upcoming episodes, Noble did say that the future of the show itself appears secure. He quoted Fox Entertainment President Kevin Reilly as saying, "If these people can maintain 1.5 (ratings) points, then they're not going anywhere."

"Well, we've not only done that, we've exceeded it," Noble said. "And we set a record last week for what they call DVR Live +7," which tracks time-shifted viewing among people who record a show to watch later. "We increased 71 percent in the +7s, which has never been before done by anyone. So based on those figures, I think we should be fairly safe. Unless Kevin breaks his word, and I don't think he will."

Fringe airs Fridays at 9 p.m. ET/PT on Fox.