Last season on Fringe, the series did the seemingly impossible by focusing on both our world and "over there" -- two universes, one prime and one parallel -- when Olivia and Fauxlivia switched places. Peter used the machine and experienced a vision of the future in which the parallel universe is destroyed and our universe is threatened extinction. He created a bridge between the two universes to save both and thus erased himself from history. And that was only season 3.
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Considering that the show has literally retconned the entire series by erasing a main character from the history of these two universes, expect everything to be slightly different on Fringe season 4. This is a Peter-less timeline, and season 4 is now really a demonstration of how influential Peter has been in these characters' lives, especially for our Walter and Olivia.

There is no doubt that Peter humanized and softened both Olivia and Walter. But how will that change in Fringe's fourth season without him? How has Olivia dealt with her experimentation as a child without Peter? Her powers? Speaking of, producers hinted at Comic-Con that we haven't seen all of Olivia's powers. Fauxlivia, presumably, still doesn't have them, but remember, this is Fringe.

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Walter especially is very different. This is a Walter who never had Peter take him out of the mental institution; instead, Olivia did. Expect to see a different version of Walter in Fringe season 4 because of this -- one weirder and now introverted. Also, what does that mean for Walternate? What happened that started a war if Walternate's main justification doesn't exist anymore?

Outside of the trio, other characters are affected. Walter's babysitter/lab assistant Astrid is now out as an active field agent with a gun! Fringe season 4has also added fan favorite Lincoln Lee, played by Seth Gabel, to the main cast. Gabel will be on double-duty as he plays the Fringe Team Leader "over there" and a straightlaced FBI agent unfamiliar with the Fringe team over here.

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In additional casting news, a new recurring heroine/villainess is played by actress Michelle Krusiec. Her character is under a tight lid. Is she Peter? At this point, the show could very well convince me. I trust this show too much.

And finally, without Peter in the picture, what does that mean for Joshua Jackson on the fourth season of Fringe? Don't worry -- he is still a part of the Fringe family. Yet one of the greatest mysteries this season is how he will return and what questions and answers are asked and resolved. The "recasting"-of-Peter video shown at Comic-Con suggests that Jackson might be portraying an Observer. Is Peter an Observer now? Is that video an Easter egg?

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