to the chest, he warns Olivia that he has seen all of the possible timelines, and the result is always the same: Olivia has to die. He then disappears before Olivia can call an ambulance to help him. He resurfaces several episodes later in "The End of All Things", during Peter and Walter's search for the kidnapped Olivia, where he appears in Walter's lab, and is dying from the gunshot wound. In an attempt to discover the location of Olivia, Peter enters September's mind using the same method Olivia used to enter John's in the pilot. September has no information on Olivia, but does tell Peter that the Observers come from the future to observe their beginnings, and explains that he has interfered in the past. It is explained that this was an attempt to correct the timeline after accidentally preventing Walternate from discovering the cure to save Peter, thus beginning a chain of events that led to the war between the two universes. He also cryptically says, "they are coming". Before Peter can ask who, September tells Peter to "go home" and yanks him out of his mind. In the real world, September disappears from the lab, having been taken by the others. In the next episode it is revealed that he planted a message in the form of a black dot in Peter's eye which contains an address in New York. Peter goes to the address to discover Observer technology in an apartment and a cylinder like the one in "The Arrival" which teleports a fully healed September to the apartment. Peter begs September to send him back to the original timeline but September assures him that this is where he is meant to be before teleporting away. In the 5th season episodes "Anomaly XB-6783746" and "The Boy Must Live", it is revealed that after the events of the fourth season, the Observers removed September's observer technology and conducted "biological reversion" experiments on him, causing him to transform into a human. As a human, he assumed the name Donald O'Connor. An Observer (either September or a different unnamed Observer) appeared in every episode of Fringe, albeit sometimes only as a brief cameo. As a tie-in with the show, actors playing Observers appeared in the audience of other FOX network shows, including American Idol and the 2009 Major League Baseball All-Star Game. In creating the Observers, the producers had