<Tr> <Th> 76 </Th> <Td> 11 </Td> <Td> "Making Angels" </Td> <Td> Charles Beeson </Td> <Td> Akiva Goldsman & J.H. Wyman & Jeff Pinkner </Td> <Td> February 3, 2012 (2012 - 02 - 03) </Td> <Td> 3X7011 </Td> <Td> 3.20 </Td> </Tr> <Tr> <Td_colspan="8"> Alternate Astrid discreetly visits her counterpart to talk about her recently deceased father . Fauxlivia is sent to escort her back . Peter and Olivia track a killer targeting people who will die a painful death to save them from suffering, using a toxin from the future . With help from Alternate Astrid, they identify their man as a TSA agent who cleared all his victims prior . He gained knowledge of their future by solving certain equations when he was a mathematics professor at MIT . Having survived a car accident that took his father and twin brother, he overheard his mother saying that God had taken the wrong son, which motivated him to act as a savior . When the Fringe team is about to arrest him, he fires a gunshot towards Olivia, purposely missing her, upon which she returns fire and kills him . The parallel versions of Astrid and Olivia return to their universe after warm goodbyes . Two Observers, including December, learn the killer found the toxin he used on Reiden Lake; it had been lost by September when he had unsuccessfully tried to save Peter . December learns that Peter has reappeared in this timeline . </Td> </Tr> <Tr> <Th> 77 </Th> <Td> 12 </Td> <Td> "Welcome to Westfield" </Td> <Td> David Straiton </Td> <Td> J.R. Orci & Graham Roland </Td> <Td> February 10, 2012 (2012 - 02 - 10) </Td> <Td> 3X7012 </Td> <Td> 3.05 </Td> </Tr> <Tr> <Td_colspan="8"> Peter, Olivia and Walter come face to face with a Fringe event as they get trapped in Westfield, Vermont, a town that there's no escaping from and most of whose inhabitants act delusionally . Walter realizes they have been fused with their doppelgangers from the parallel universe, giving them a new set of memories . The town has been merged with its counterpart too, which makes it unstable . When it is on the point of collapsing, Walter and Peter locate an area that acts like the eye of a storm, and lead all survivors there . The rest of Westfield vanishes . The remainder of the Fringe team is able to reach the survivors and help them; Olivia learns that they found several strange devices equipped with amphilicite planted around the perimeter of Westfield and believes them to have been set by David Robert Jones . Throughout her stay in Westfield, she has remembered more and more things from the original timeline . At the end of the episode, she kisses Peter as though they are still in a relationship . </Td> </Tr>

When does olivia remember peter in season 4