[ If Peter “never existed”, then why do we even know about the parallel universe? The destruction of the other side began when Walter stole Peter from the other side. If Peter never existed, then no degradation would be happening and there would be no “war” between the two universes. ]
Peter existed as a child in both universes, he died from the illness in this universe, then when our walter stole the alternate one when they went through the machine the Observer didn’t rescue them from the water when they fell into the lake so Walternate still lost his son, only time he died from drowning in the lake. Walter somehow survived, maybe he was able to get out from the ice on his own.
If it wasn’t for the observer saving yound peter from the ice he wouldn’t exist as an adult in the timeline. Maybe the child peter was preserved, as evidenced by the altered timeline Walter working on somethign to revive that dead bird....
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.