Warning: SPOILERS for Star Trek: Discovery season 3, episode 9, "Terra Firma, Part 1".

Star Trek: Discovery season 3 has returned to the Mirror Universe but the show appears to be retconning the alternate reality's history, which could have unknown effects moving forward. Ever since the U.S.S. Discovery arrived in the 32nd century, Emperor Philippa Georgiou (Michelle Yeoh) has received a new prominence because she's suddenly dying. This, coupled with new revelations about the relationship between the Prime and Mirror Universes, looks to be changing what we know about the parallel timeline that was ruled by the Terran Empire in the 23rd century.

As seen in Star Trek: Discovery season 1, Philippa Georgiou was Emperor in the Mirror Universe until 2257 when the Prime Universe's U.S.S. Discovery crossed into the alternate reality. Discovery was led by Captain Gabriel Lorca (Jason Isaacs), who was also from the Mirror Universe and was trapped in the Prime universe for a year. Lorca returned to finish his plot to overthrow Emperor Georgiou but he failed when Michael Burnham (Sonequa Martin-Green) sided with Georgiou. The Mirror Universe's Michael Burnham was already dead, but the Emperor still felt a powerful connection with the doppelganger of her adopted daughter from the Prime timeline, and vice versa. Because of this (misplaced) loyalty, Michael saved Georgiou's life and brought the Terran despot back aboard Discovery when they returned to the Prime Universe.

Related: Star Trek: The Mirror Universe's History Explained

But after joining Discovery's one-way trip to the 32nd century, Emperor Georgiou is rapidly dying due to the deleterious effects both jumping across parallel dimensions and time traveling is having on the Terran's molecules. 32nd-century science has no known cure for Georgiou's condition, but Discovery's sentient computer offered a chance for her salvation with a 5% chance of success: taking the Emperor to the planet Dannus Five, where Georgiou and Burnham encountered a mysterious being who calls himself Carl (Paul Guilfoyle). Carl offered Georgiou a doorway that could lead to the answers she seeks, but it transported the Emperor back to the Mirror Universe of the 23rd century - approximately one year before the U.S.S. Discovery's arrival and the disastrous end of Georgiou's reign as Emperor.

However, even though she remains a wicked Terran, Emperor Georgiou is visibly a changed woman after her experiences with Discovery in the Prime Universe, a fact that the other Terrans about the I.S.S. Discovery silently noticed. And perhaps, Georgiou was already undergoing a shift in the past since the Mirror Michael Burnham sensed she was weakening and joined Lorca in plotting their coup against Georgiou. Although Georgiou played along with her memories of what happened on the day Carl returned her to, because she has "seen the future," the Emperor decided to change what she remembered as history - and in doing so, Georgiou (and Star Trek: Discovery) may have just rewritten the canon of the Mirror Universe.

The Distance Between The Prime And Mirror Universes Is Expanding

Star Trek Discovery Georgiou David Cronenberg Section 31

Thanks to the Temporal Wars and a time traveler from 2379 who crossed over from the Kelvin Timeline named Lt. Commander Yor, the Prime Universe's United Federation of Planets learned a great deal about the Mirror Universe and, specifically, about Terrans, who have certain biological differences that prompt them towards malevolence. But perhaps the most alarming fact the Federation learned is that the distance between the two universes is continually expanding. Crossovers were more frequent from the 22nd to the 24th centuries but, as Kovich (David Cronenberg) assessed, it has been 500 years (circa the 2600s) since anyone jumped from the Mirror to the Prime Universes or vice versa.

This makes Georgiou's predicament even more unique since she is the first Terran Kovich has met and the first denizen of the Mirror Universe to spend copious amounts of time in the Prime Universe. Because she time-traveled and jumped from a parallel universe, every molecule in Georgiou's body is rebelling to be returned to its point of origin, which is tearing her body apart. However, the Federation has iron-clad rules about breaching universes and time travel, thanks to the Temporal Accords, so even if they had the technology to return Georgiou (which Kovich tacitly implied exists), there are laws preventing them from doing so. But this begs the question of what the state of the Mirror Universe has been for the last several centuries since the most recent chronological glimpse of the alternate reality seen by fans was in the 24th century of Star Trek: Deep Space Nine season 7.

Related: Star Trek: Every Mirror Universe Episode

Georgiou Is Dying And Her Salvation Is Tied To The Mirror Universe

Star Trek Discovery Carl Newspaper

Carl, whoever and whatever he is, also raises myriad questions. Assuming he is a powerful cosmic being of some sort - possibly a member of the Q Continuum - Carl did, in fact, have the power to return Emperor Georgiou to her original universe and timeline. This means what Georgiou is experiencing in "Terra Firma" is actually happening thanks to time/dimension travel and it's not a simulation of some sort happening in her mind or in a holodeck. A clue that this is indeed the case is when Carl told her she would no longer be suffering from her illness where she's going because she would have returned to her proper universe.

But somehow, Emperor Georgiou's life being saved is tied to the events in the Mirror Universe in 2256, specifically the time of the First Uprising, which was the launch of the Imperial flagship, the I.S.S. Charon, and the same day that Lorca and Michael betrayed her and attempted their coup. However, Georgiou returned to 2256 armed with the knowledge of how events played out, which was disastrous for her reign and for everyone involved. The Emperor surmised that changing what happened is the key to how her life will be saved - but that means altering the canon of the Mirror Universe.

Georgiou Sparing Michael Alters The Mirror Universe's Future

Mirror Michael Burnham

The Mirror Michael Burnham, and Georgiou not executing her for treason as she did in the past that she remembers, may well be the key to what could ultimately save Georgiou's life. (Which attests to Michael's importance in both the Mirror and Prime Universes.) Mirror Michael did not appear and was presumed dead in Star Trek: Discovery season 1's Mirror Universe saga but season 3 has revealed that the Emperor killed her renegade child for her role in helping her lover, Gabriel Lorca, stage their failed coup. As a Terran, Georgiou never expressed regret for what she did, but her time with the Prime Universe Michael has clearly softened her in regards to both versions of her adopted daughter in either reality.

Georgiou didn't execute Mirror Michael in "Terra Firma, Part 1", but she did murder the Mirror Paul Stamets (Anthony Rapp), who tried to assassinate her, and Stamets wasn't dead in Star Trek: Discovery season 1. These two major changes in the timeline mean that moving forward, history will not play out as it had before (or perhaps as it was meant to). "Terra Firma, Part 1" ended on a cliffhanger that left Georgiou and Mirror Michael's fates hanging, and it implied that their underlings aboard the I.S.S. Discovery led by Captain Sylvia Tilly AKA Captain Killy (Mary Wiseman) know something is gravely wrong with Georgiou and could take matters into their own hands, and this would alter the trajectory of the Mirror Universe even further.

However Star Trek: Discovery season 3's retcon of its season 1 Mirror Universe saga turns out, and whether or not Emperor Georgiou's life is indeed saved, changing the events of 2256 will likely affect everything that follows. The domino effect may lead to the alteration of key events like Captain James T. Kirk (William Shatner) convincing the Mirror Spock (Leonard Nimoy) to "save" the Terran Empire from extinction in Star Trek: The Original Series' "Mirror, Mirror", which resulted in the Klingon/Cardassian Alliance conquering the Terrans in Star Trek: Deep Space Nine's 24th century. But Emperor Georgiou's salvation could also somehow affect how the Mirror and Prime Universes are expanding apart from one another. Reversing this dimensional division would further change the destiny of the Mirror Universe in Star Trek: Discovery season 3.

Next: Star Trek: The USS Discovery's Season 3 Refit Breaks Its Own Canon