Who is the observer in fringe

So I know last season there was the episode that helped to kick off this season where they go forward in time and there's an observer occupation, but when exactly was it that the observers became evil? I don't mean in their own history, but in the canon of the show.

I always had the impression that the observers wanted to fix the world that was broken when Walter went to the alternate universe and stole Peter. I never got the impression that they were evil or good, just that they were a natural force that tried to fix the universe when it got broken. I never read any maliciousness into their characters. Were there hints that I just missed along the way.

September (played by Michael Cerveris), often referred to as The Observer, is a mysterious figure seen at the scene of many Pattern-related events. Like other Observers that have appeared on the show, September is only seen wearing a plain black suit and black fedora, and is pale, bald, and lacks eyebrows. They exhibit several strange mannerisms such as awkward phrasing when talking, a preference for extremely flavored, like spicy or salty foods due to an extremely dulled sense of taste, and the ability to appear or disappear when one looks away. They also use an alien written language with which they maintain copious documentation in small notebooks. Though the Fringe division is aware of the Observers, their intent is not yet known, though believed to be related to the Machine and the conflict between the two universes. They possess uniquely advanced technology, and appear to be temporally aware of time, including the ability to travel in time and between the two universes; the Fringe division finds evidence of Observers at several historical events but looking the same as they do in the present. Like September, the other Observers appear to be named after months, including "August" and "December". The episode "Inner Child" introduces the Fringe division to a child that appears to possess many Observer-like qualities.

In the episode "Peter", September is a catalyst in Walter's abduction of Peter from the parallel universe; September arrived wanting to see the creation of the cure by Walternate that would have saved Peter, but instead distracted Walternate from witnessing a critical test result. When September saw Walter watching through the window-like device, he informed his fellow Observers that he could correct the situation; later, after Walter returned with young Peter to the prime universe and fell through the frozen lake's ice, September rescued them from the freezing water and told Walter, "The child must live".

September and the other Observers have since monitored Walter and Peter. In the second season's finale, September is responsible for alerting the Fringe division to the dangers of Peter being taken back by Walternate to the parallel universe, ultimately leading to their rescue attempt. In the third season episode "The Firefly", September conducts a convoluted experiment to test Walter's resolve to give up Peter for the greater good when the time comes.

In the third season finale episode "The Day We Died", a gathering of ten Observers appeared on Liberty Island to watch and comment on the disappearance of Peter Bishop from existence.

Later, he is ordered by his superior to ensure that Peter's status as nonexistent continues, and constructs a device to erase all lingering memories of Peter from Walter. However, at the last moment he disobeys his orders and deactivates the device, allowing brief apparitions of Peter to appear to Walter and Olivia.

In "Novation" Peter mysteriously appears in the new timeline. After being taken into custody by the Fringe Division, he learns that the point of divergence in the timeline is that September never saved him from drowning in Reiden Lake when Walter brought him over from the alternate universe. He also learns that, in the new timeline, the Fringe Division is unaware of the existence of the Observers.

September later appears to Olivia while she waits for Peter and Lincoln to return from the alternate universe. Mysteriously wounded from a gunshot 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 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 in 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) has appeared in every episode of Fringe, albeit sometimes only as a brief cameo. As a tie-in with the show, actors playing Observers have 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 some idea of how they would be introduced into the show, starting as a background character and only becoming a significant figure by the midpoint of the first season. Though they had some idea of the Observers' role, they gave Cerveris much leeway to develop the character in the manner he wanted, from choosing the outfit he would wear to his language mannerisms. Cerveris further is credited with creating the written Observer language during his scenes in "The Arrival", which the production team later extrapolated into a complete language for the show.

The Observers are hairless pale men that typically wear grey suits and fedora hats. They are quiet, tending to mind their own business and interact only minimally with others. Appearing in every episode, they tend to appear before significant events in history. They use advanced equipment, such as advanced communication devices and compact binoculars, and they employ an alien written alphabet. A distinguishing trait is their diminished sense of taste, and it is often shown that they can only taste very spicy food. Observers ask have diminished emotions.

The Observers are able to predict future events, and they are able to travel in time and across universes without difficulty because of their advanced technology. In "The End of All Things", it is revealed that the group of Observers seen in the first four seasons are a team of scientists from the far future, or at least from one of humanity's many possible futures. This group of Observers traveled to their past to observe the events that led to their creation.

The group of Observers seen in the show during the first four seasons had designated code names, with each individual referred to as a month of the year: September (Michael Cerveris) appears in every episode in the first four seasons, even if only in a cameo shot, while December (Eugene Lipinski) and others appear with less frequency. In the episode named "August" a rogue Observer named August was shown (Peter Woodward) who sought to try to change the fate of a young woman contrary to the Observers' practice.[23]

September is seen in both universes during the episode "Peter", both to cause Walternate to miss a critical observation for the cure for Peter's illness in the parallel universe, and to rescue Walter and Peter after they fell through the ice in the prime one.[24]

The episode "The Firefly" involves a series of events temporally engineered by September to force Walter to make a choice regarding Peter's safety as to prepare him for a future event. These events included bringing the son of Walter's favorite musician into the present to draw Walter's attention.[22][25]

After Peter's disappearance in the third season's finale, "The Day We Died", the Observers remain aware that Peter has vanished, claiming he has been erased from existence.[16]

The episode "Letters of Transit" reveals that by the year 2609, the Observers had wreaked environmental havoc on the Earth - to the point that they decided to simply travel back in time to the early 21st century and colonize the planet before the environmental destruction occurred. In the year 2015, the Observers invaded from the future, instituting "The Purge" and killing many humans. Although humans continued to resist well into the year 2036, the Observers largely succeeded in conquering the planet. The fifth season focuses on events in this future, where the Observers, run by Captain Windmark, maintain control on the remaining humans through their own abilities and the assistance of human Loyalists. A rogue group of humans, the Resistance, fight against the Observers, and have come to learn much about the Observers' abilities, including that many extend from an implant in the back of their neck that expands their mental processing power at the cost of emotions. Due to coming from a much more polluted Earth from six centuries in the future, the unpolluted atmosphere of 21st century Earth is too "clean" for Observers to live in for prolonged periods of time (or perhaps, simply uncomfortable): thus after conquering present-day Earth, the Observers set up terraforming factories to increase the level of carbon monoxide in the atmosphere, which will cut short the life expectancy of regular humans by decades.

In the episode "The Boy Must Live", September explains that the final emotionless version of the Observers were "born" out of an experiment performed by a Norwegian scientist in 2167. That scientist was the first scientist to replace space in the brain usually designated for negative human emotions, such as rage, with brain cells tuned to increase intellect. Many generations of humanity later, brain cells currently tuned for emotions (not just the bad ones but the good ones as well) were engineered to be intellectual brain cells. Higher and higher intelligence was the ultimate goal.

The experimenter modified human genes to displace certain emotional facilities for improved mental abilities, and the success of the experiment eventually led to the development of near-emotionless humans with high levels of intelligence that became humanity's evolutionary future - aka "the Observers." Without emotions, there was no urge to procreate, and thus the Observers developed technology to artificially grow new Observers using Observer DNA via maturation chambers.

During the out of body growth process, Observers were grown from embryo into fully matured adults. Sometimes, the growth process would create genetic anomalies; typically, the Observers would destroy any anomalies. The Observer September encountered one such anomaly - Anomaly XB-6783746 - and was affected when he learned he was the "genetic parent." September did not destroy his progeny but developed a strong desire to save his son - Anomaly XB-6783746 - after scans revealed that the Observer was even smarter than mature Observers while possessing all of the emotions sacrificed so easily starting in 2167. His son, later named "Michael" by human caretakers during the initial Earth invasion by the Observers- possessed both human emotions and Observer-level intelligence. September then hid the child in the early 21st century (which was humanity's future but centuries before September's time). The series' finale concluded with Walter's successful effort to transport "Michael" to 2167 to convince the Norwegian scientists to abandon any efforts for reproductive medicine which might involve sacrificing emotions. These emotions are the backbone of humanity's conscience and moral compass and when humanity loses its collective moral compass in the pursuit of raw intelligence - we become the cold and calculating husks deemed "the Observers."

In the series finale, December explains that all twelve members of the science team had begun to experience varying degrees of human emotion, and that they had all agreed to keep these emerging emotions to themselves, in order to remain undetected by the other Observers in the future. They were also unaware that their mission of observation was also a precursor to the invasion that would see the Observers take over in 2015.