Forget everything you think you know about the world of Fringe. After the events of season three's finale, you are now entering a whole new world. It may look a lot like the show we once knew and (most of) our favorite characters are still, but there's a void in the middle of this show and his name is Peter Bishop. How Fringe attempts to rewrite the history of its characters with a major influence in their lives missing is one of the many things that makes the new season incredibly exciting.
While there was a lot to dislike about "The Day We Died," the final moments were jaw dropping as Peter, having glimpsed a future he did not like, built a bridge between the universes so that now our characters and their alternates could begin working together. In the middle of explaining this, he blinked out of existence and no one there seemed to have any recollection that he had ever existed. This is only partially true, as we learn in the premiere episode that the Observers have rewritten history so that both versions of Peter died as children. This means there are still holes between the universes and the war between the two Walters has still been waged.
The opening episode of season four spends a lot of time getting its bearings and re-introducing to a world we thought we knew, but now changed in incremental ways. Peter Bishop, like George Bailey in It's a Wonderful Life, had a great impact on those around him, even the people he wasn't terribly close to and the show needs to take some time to let us know how this new world is different. This is done, primarily, by introducing a new recruit into the Fringe team. This reality's Lincoln Lee—a character we've only met briefly—finds himself in the middle of a Fringe investigation and, through persistence, works his way into the fold.
While there's a lot to like about the premiere episode, it does suffer a bit from the weight of being something of a second pilot and being forced to convey different versions of stories we've already seen. It's in the second episode that Fringe really begins to pick up speed as Olivia finds herself working with the other side's Fringe division to catch a serial killer by investigating his alternate. Not only does this episode show the story potential of the two universes being brought together, it forces both Olivias in the same room together which makes for some instant fireworks.
Of course, if you're clammoring for answer to the question, "What happened to Peter?" you're in for a disappointment. Much like it took a lot of time in season three for Olivia to return from "Over There," it doesn't seem like Peter will be returning any time soon. However, the Fringe team has made no secret that Joshua Jackson is still part of the show, so we know he's not gone forever. We'll just have to be patient and let it play out slowly.
Season four of Fringe premieres Friday 8pm on Fox.