It’s been a few weeks since Peter went into the mindscape of the Observer to watch the big bang and chat about nature of reality. Peter learned the origins of our bald watchmen and that September is going against his fellow monthly doppelgangers in the hope of correcting the mistake he made by distracting Walternate while he was coming up with a cure for the strange disease that attacked Peter as a child. Understandably, "Fringe" gave us some time to process it, but now it's back to delve into the greatest scientific mystery: love.
When we last left off, the new timeline version of Olivia was overwhelmed by memories from the original Olivia. Walter believed these memories were caused by Peter’s presence, magnified by the Cortexifan the shape shifters were slipping Olivia. At first, Peter was all for it, happy to have at least part of his Olivia back, but Walter warned him it was wrong and told Peter to stay away. If there’s anyone who knows a thing or two about trying to regain a lost loved one, it’s Walter.