Originally Posted by URFloorMatt
My current theory is that the 12-man Observer team we've been exposed to in the present timeline are just a small science team, which may or not be rogue, and not indicative of the species generally.
While they may be capable of exploring every timeline, it's not clear that they're all that methodical about it. They have essentially turned 2015 into their lifeboat because of issues in the future--for a species that can foresee all futures, allowing themselves to make Earth uninhabitable is an unusual and glaring mistake to make.
Here's a theory. DRJ's universe collapsing scheme succeeds, which collapses not just Red/Blue/Amber, but a host of universes--including all futures in which the Observers exist. As a result, there is now only one timeline through which they can move, and they have been hamstrung for some reason by DRJ's actions, such that they can only move between 2012 and 2609. This is why their future was destroyed. This is why they "turned" evil--self-preservation.
September did tell Peter that they were scientists I believe... so even if the Observers as a race go rogue, it still could be that even the people against September are not the ones who took over in the future.
I think sometimes we are seeing things out of order.
Remember how they all wondered why Massive Dynamic created that machine (from appearances that it looked like MD tech) and then why it was keyed to Peter's DNA? Now this season we see Walter trying to make the device work from Peter's DNA... which leads to the possible conclusion that the universe we see now sort-of precedes the season 1-3 timeline because that timeline happened after this timeline makes the machine respond to Peter!
Then we have the Observers... They *could* be trying to ensure they come to be to protect the future OR because they know the Fringe team at some point beats them down and they actually want to change the past to prevent that while not eradicating themselves in the process.
Clearly last season, the future we saw was beyond the point in this new future where Observers had taken over... so the season 3 timeline did not result in a future where Observers came back and took over!
The question then is... were the Observers trying to create this new future where they rule OR one in which they don't rule.
Also... I found myself thinking back to the original Bell + Walter cortexiphan trials... and that William Bell believed there was a war coming.
Now... Walter and most of us have been led to believe that "war" was the war between the red and blue universes over the damage done... BUT what if that wasn't the war Bell predicted?
What if the war Bell was preparing for was a war against the Observers... as noted in this future episode, Peter + Olivia's daughter could not be read by the Observers... implicating that perhaps the cortexiphan trials result in humans that are able to better fight against the Observers.