The Boy Must Live 

Walter's encounter with "Anomaly XB-6783746" did more than just show Walter where September has been hiding... It bridged two timelines.

But when we first heard the phrase "The Boy Must Live" all the way back in the S2E16 episode "Peter" - We thought all along, this was in reference to Peter. But as with all phrases we hear repeated in Fringe, "There is more than one of everything" - Including meanings for these phrases.

September gives us the future history of The Observers, and he even explains what the "plan to defeat the observers" is-To be blunt, I don't believe it. Or, a better way to put this is, I don't "trust" September, but only in that I think he was omitting something in his overly simplistic explanation of "The Plan" - He's never been 100% transparent, and as a human, he would be even more able to commit misdirection. But he has been rather good at setting out the Hitchcockian Maguffins and getting Fringe Division to chase them. So I'll just extend myself again and say, "I don't think we've been told the whole worm-can" - And with only 90 or so minutes of circular story to tell, we'll see if the bag of snakes "Donald O'Conner" has laid out is straight or not.

And if we put this episode in its place in the timeline, September seems to have known all about this from the first time his shiny-domed head was seen. I've tried to predict in my mind how these four and a half years worth of stories were going, and I've been wrong each time. So I'm expecting to be wrong now, and that has been my whole fascination with this show and this style of storytelling. If the show-runners of Fringe set out to accomplish something, it has been to give us a story that bends back in on itself and can me retold as many ways as there are stars in the sky.

We're told some disturbing, but not wholly unexpected things in this calm before the storm. Olivia early on says that, if the "Plan" succeeds, then time will reset. With four universes worth of time's arrow to choose from, we'll have to see where the roulette-ball will roll.

In this season we've seen Fringe Division take some very wrong turns, but here, even without his "Observer Device" Donald/September seems to be acting according to a predetermined purpose. The only ones who can't see that purpose are Walter and crew, and of course we, who are watching this unfold in "real time"