Yeah but that's my point... We assume that the observer saved Peter in the lake because he felt bad about distracting Walternate so he wouldn't find the cure... But from what we've heard, the "mistake" that got "corrected" is Peter not being saved in the lake... which means the Observer still distracted Walternate from finding the cure for Peter, thus inciting Walter to cross over anyways and start the conflict between both worlds.
Wouldn't it have been much easier for the observer to not distract Walternate in the first place, since one would think that was his original interference? The one that caused the whole situation to snowball from there?
Which leads me to think that distracting Walternate was actually part of the Observers' plan. And seeing that for some reason I seem to remember that they said something about many Peters dying of the same cause (which was a very rare condition to begin with), it would seem that one Peter surviving is a problem for those guys...
Up to now, the only obvserver who's interfered to help Peter is the one we've seen since the begining, and he seems to be having some moral issues... The others seem bent on having Peter not exist... Why would they go to so much trouble to erase all trace of Peter if they're only 'observers'?
Plus hey, we've seem other observers interfere... like hell they're only observing... they've been doing a whole lot more since the begining of the series... There was the weird machine they had burrowed somewhere for starters... why would they need to plant gizmos anywhere if they're only obvserving? I'm thinking the observers might end up being the villains here... and our 'famous' obvserver might be the rebel one that'll help the Fringe guys...
Well I guess I was right, for once
Man I really hope they don't get cancelled... Fringe's been one of the few good shows recently =(