The central mystery heading into the new season of Fringe is a gamechanger of sorts for the team behind the Fox sci-fi series. Introducing a second universe in the first season was digestable and doing a switcheroo at the end of Season 2 was jaw-dropping, but erasing a main character from existence? Talk about gutsy.

In a chat with The Hollywood Reporter, executive producers Jeff Pinkner and Joel Wyman discussed their game plan on how they'll deal with Peter's (Josh Jackson) absence and whether new series regular Seth Gabel is Peter's temporary (or permanent) replacement.

[Warning: Minor spoilers up ahead.]

"Without spoiling anything, we're not going to drag it out until the point of frustration," Pinkner says of Peter's disappearance introduced in last season's closer.

And while "the story is not going to be wrapped up quickly," Pinkner reassures that when Peter "does return, it's not a simple, oh, he's back and all is well. (John Noble told THR recently that Peter would be back "earlier" rather than later.) Clearly all is not the same as it was and that's not going to change anytime soon." When asked whether Peter would have the same history and memories from the beginning of the series, Pinkner was adamant on not revealing much: "You know us. We don't like to spoil too much."

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Though viewers are already familiar with Lincoln Lee (Gabel), the version of the character "over here," narratively speaking, is filling the void left by Peter. But Wyman hinted that "emotionally," Lincoln is "definitely not" taking on the Peter role.

"Peter is Peter and what he brings and what he is, is not lost," he explains. "It should be clear that we're not saying that the last three seasons didn't happen. That's not what we're saying at all. Peter's still very relevant. But narratively, [Lincoln] represents a very important thematic element that we are focusing on this year. He's important to the plot and the story that way. We're always coming from a place of theme, so he's a metaphor for a couple of things we're trying to get across this year."

In the first two episodes of the new season, the producers are tasking viewers to take note of which universe ("over here" or "over there") will see more drastic changes.

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"His influence on the alt universe has been much less significant and in the history of our show, far more recent. So the fact that he 'never existed,' the difference is on our side and felt more specifically and significantly than the differences on the other side," Pinkner says, "where presumably the Fringe team is exactly as we found them back in Season 2."

He adds, "The things are much more similar to our memory of them on the other side than they are on this side."

The Fringe bosses hinted that familiar faces will return, including Kirk Acevedo, who is now on Prime Suspect, pending his availability. "And some faces that perhaps you're not expecting to see return as well," Pinkner said.

Are the producers aware of the sudden trend of television shows featuring twins, dopplegangers and multiple universes? "Certainly there was an episode of Phineas and Ferb and traveling to a parallel universe and dealing with evil dopplegangers and a mad scientist," Pinkner said with a laugh. "It's either really awesome flattery or it's just an idea in the zeitgeist."

Fringe premieres Friday at 9 p.m. on Fox.