I’ve never rewatched the pilot episode of Fringe, and at this point, I’m not sure that I ever will. The show is now so radically different from what it was back then that doing so would feel like a betrayal of sorts. What started out as a horror procedural has now morphed into a densely layered sci-fi epic, complete with wormholes, alternate universes, and now, time travel.

Time travel was introduced to Fringe back in season 2’s “White Tulip,” and at that time, I never would have predicted that it would come to play such an integral role in the series. In this week’s stunning and moving season finale, the show gave us a peek into what life might be like for our little Fringe family 15 years in the future. The Fringe Division of the FBI has been greatly expanded. Astrid is now a full-fledged Fringe agent, and Olivia’s niece, Ella, is a rookie. Peter also works for Fringe Division in a sort of commander position, while his wife, Olivia, seems to have stepped into Broyles’s old role. As for Broyles, he is now a U.S. senator. Most importantly, though, Walter has been thrown in prison for his crimes against the fabric of the universe, and Walternate now resides in our universe, his universe having been destroyed.

Despite being about an entirely different setting than the present day, “The Day We Died” felt very much like an episode of Fringe, and a damn good one at that. It was gripping, suspenseful, emotional, and just a little nuts. More details after the jump.

As evidenced by its portrayal of the alternate universe, Fringe is adept at constructing hypothetical societies and bringing them to life. This episode gave us a portrait of our own society 15 years in the future, when fringe events have become commonplace. Fear is the new status quo; young children live in ignorance of it, but adults who were alive prior to the Machine’s activation are forced to live with the knowledge that things weren’t always this way. Walter, the man responsible for setting off the disintegration of the universe, is now the most hated man alive. He is so hated, in fact, that releasing him temporarily to help fix the very problem he caused is a politically difficult proposition.

For all of the recognition Fringe receives for its treatment of macro-level issues, it is equally adept at reflecting them in the characters’ personal lives. Olivia and Peter want to start a family,1 but Olivia is reluctant because she is scared to raise a child in a universe where a wormhole could swallow her up without warning. Meanwhile, Walternate sees Peter’s activation of the Machine and the subsequent destruction of the alternate universe as a personal betrayal, prompting him to assassinate Olivia in cold blood.

Only a show as well-crafted as Fringe could seamlessly intertwine personal issues with large-scale ones, and only a show as inventive and daring as Fringe could deliver all of this in a suspenseful package against the backdrop of time travel and alternate universes. Truly, “The Day We Died” was a fantastic way to cap off the season.

However, I do have a concern: I’m not sure that my brain can handle it. There’s a reason that time travel is rarely well-implemented in fiction, and the reason is that time travel is really damn hard to write about. There have to be rules governing time travel, or else the show becomes messy, confusing, and self-contradictory. Thus, a lot of shows, even hardcore sci-fi ones, have tended to avoid it. While I applaud Fringe for incorporating such a difficult element into its narrative, I’m already slightly lost,2 and part of the problem is that the episode didn’t explain the logistics of or the rules governing time travel very well. I’m still a little fuzzy on how it came to be that Peter no longer exists, for instance. In fact, I’m starting to wonder if the show would have been better off just sticking with one complicated element, alternate universes, and eschewing the second, time travel, altogether.

But that’s a concern for season 4, and it would be silly of me to dismiss the time travel aspect of the show before it plays out more on screen. For now, I’m very pleased with this excellent season finale. Here’s hoping that season 4 is just as good, if not better, than this one.

1 Sidenote: Anna Torv and Joshua Jackson are much better at playing a long-married couple than they are at playing a young couple in love. They really played well off each other in this episode.

2 As I imagine Lost fans felt pretty much all the time.