I'm waiting to see that September is actually Peter's son, Henry. Now how twisted would that be: all five years of Fringe happened because September went back in time to check out his world's version of Ancestry.com, and in the process distracted Walternate so that he didn't see the formula that would of saved Peter's life. Everything he has done has been to correct his error - Olivia, Peter, Walter and all the others - were simply collateral damage in his attempt to correct the history he disrupted.
That's not twisted at all...In fact, I think that would be brilliant! I actually stated this in another thread and added that if he is not Peter's son, he is probably somehow related and is actually a Bishop. Also, codenames like September were necessary so that when Observers travelled back into time, and for some reason found it necessary to directly interract with people, their ancestors would not be able to identify them by name. This would also explain why September went back into time to witness Walter's scientific achievement... of all incidents to see since he had some sort of family/quasi-emotional investment into it.