It was an interesting way to demonstrate how the two universes are now in partnership, as the terms of their peace accord is cooperation with criminals matters, and seeing McClennan essentially investigate his own "evil twin" made for compelling television.
What was especially enjoyable was veteran character actor Pyper-Ferguson's performances of the two McClennan's, and the tragedy of how their lives diverged: one receiving a savage beating from his father after his stash of tortured dead animals was discovered, the other ran away and found unexpected love and understanding from an angelic woman called Margery (Julie Schnekenburger). One very small change in their lives, producing such radically different people, but "our John" still retained some darkness he's managed to live with, and it's that which led to him becoming a psychiatrist so he can prevent others going down the wrong path. Fringe's take on this idea was very effective and interesting (is there even another show that could handle a story like this?)... even if it was perhaps hard to swallow that the Evil McClennan would have grown up to become someone capable of creating a device that can link two brains together, with the unfortunate downside being that the "transmitting" brain will die of hypothermia.
It was also great fun to see the two Fringe teams mixing together. Anna Torv is fantastic at playing her two roles, as she gives Fauxlivia a noticeably softer attitude and relaxed body language. I especially loved the scene where Fauxlivia's dressed in Olivia's FBI uniform and is visibly uncomfortable; unbuttoning the white shirt and fidgeting with the tightness of the trousers and jacket. Torv's tremendous at reminding us which Olivia is which, at a glance. (Also note: Fauxlivia can't resist making her dyed-blonde hair looser and sexier than Olivia's, too.) Hers is a twin performance apparently beyond Ringer's Sarah Michelle Gellar (who likewise plays twins on that CW drama, but you struggle to remember which is which from the acting).
In terms of the season's ongoing concern with the non-existent Peter, we got a few scenes with a nervous Walter (John Noble) in his laboratory, covering reflective surfaces to avoid "the man" (Peter) making a reappearance, but it seems Peter's not going to be ignored so easily and has become a disembodied voice. As Broyles tells Olivia, in an unrelated scene towards the end of the hour, some people "leave an indelible mark on your soul; an imprint that can never be erased", and that's certainly true in Peter's case. How long will season 4 continue before Walter either remembers his son, or The Observers are forced to magic Peter back into being? Is he actually existing in some limbo-dimension Walter may be able to access with science?
Overall, "One Night In October" was very enjoyable stuff, and it was wonderful to see the two universes working together in a generally efficient and courteous manner. I can't wait to see a few other characters interact with their dimensional twins on the show. What will Astrid (Jasika Nicole) make of her autistic counterpart? How will nerdy Agent Lee (Seth Gabel) react when he sees his opposite is a more outgoing hunk? And of course, it would be great to get a scene with the two Walter's working together. I wonder if Walternate's personality will be any different because of the timeline change...
- I was pretty sure there was an unforgivable mistake here, as Fauxlivia mentioned she's already spoken to her universe's version of Broyles... as Colonel Broyles famously died last season. But then I remembered about both timelines changing with the non-existence of Peter, so obviously this has allowed the alternate-Broyles to live. Eager to see Lance Reddick reprise that character soon.
- In another change to the previous timeline, it's made clear that our Olivia killed her stepfather. In the original timeline, she only shot her stepfather. He survived and went on to torment her by sending birthday cards each year. I wonder how this alteration has affected Olivia. But that's a change unrelated to Peter's loss, which perhaps hints that The Observers have messed up and changed too much? Or they didn't predict the butterfly effect of removing Peter?
- There's still no clear explanation about how the universes were pinched together at a specific point by the Device that Peter was operating, if Peter doesn't exist. I hope the writers have an answer for that, I really do. It's a huge flaw in the logic, if they haven't. Last week, some commenters mentioned that Peter was probably allowed to die as a child, after Walter stole him from the Other Side and he fell into a frozen lake. That made sense to me when I read it, but I'd forgotten The Observers clearly said that Peter had never existed in the season 3 finale. So that explanation doesn't hold water now.