So, that is where my questions come from. The first episode of this current season indicates that none of the characters do remember Peter, so; as the Observers said, "he never existed". And, if he never existed, then there are problems with the whole last three seasons; or, with the first episode of this season.
Unless Bob and Emily Wake up and Bob says I just had the strangest dream
I think the Observers’ messing in the timeline goes back to when October saved altPeter on this side. That would mean that Walter had already taken altWalter’s son. That seems to be the way that memories are playing out. None of them remembers an adult Peter... yet.
“They don't remember him.” “How could they, he never existed.”
That was a big problem for me too, LibertarianLiz. Then in the first scene of the first episode of this season, two observers (October and December) meet in a diner. Heres the transcript from: http://www.fringepedia.net
THE OBSERVER: (somberly) I received your message.
DECEMBER: Then you know we have a problem.
THE OBSERVER: (emphatic) It is impossible. The timeline has been rewritten. He was erased. And yet traces of him continue to bleed through.
DECEMBER: It is, as it has always been, our responsibility to insure events play out, as they were intended, before your intervention. This started with you. It must be you who ends it. (hands over a small metallic bar)
DECEMBER: They can never know the boy lived to be a man.
THE OBSERVER: I will take care of it.
That tells me the writers made a little boo-boo on the close of last season. October (The Observer) should not have said he never existed but more like - he never existed past childhood. Walter confirms this in the 3rd episode - last night.
http://www.fringepedia.net is awesome BTW. Helps me with this amazing program.
At least this is how I understand it in the universe I'm in currently.