Mass Effect 4's trailer from The Game Awards 2020 seems to confirm the return of original trilogy companion Liara T'Soni, and when she recovers a piece of N7 armor from the snow, it seems that Commander Shepard's story also may not be over. Naturally, this has had many fans of the franchise speculating about which original trilogy companion's might be returning alongside Liara in the next game.

The lifespans of Mass Effect's species vary greatly, and there are other factors that also affect the life expectancies of Shepard's squadmates that the player can discover through their dialogue. With reasons to think Mass Effect 4 may be set long after the first three games, here's a breakdown of the lifespan of Shepard's different squadmates, and why that might impact which ones can return.

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There's good reason to think Mass Effect 4 might take place centuries after Mass Effect 3. As an Asari, Liara T'Soni could live up to 1000 years old. Since she was only 106 in the first game, the next game could be set up to 900 years after the original trilogy while still fitting with her appearance in the trailer. Not only that, but the start of the Mass Effect 4 trailer shows both the Milky Way and Andromeda. BioWare's project director Michael Gamble described this shot as "intentional."

The events of Mass Effect: Andromeda begin before Mass Effect 3, but the vast majority of the story takes place roughly 600 years in the future, with the Andromeda Initiative's members having gone into cryogenic sleep for the duration of their long flight to a new galaxy. One picture released by BioWare showed a ship named "Mudskipper," and what can only be assumed to be its crew in the distance. While these crewmembers were just silhouettes, one of them used the silhouette of Jaal the Angara from Mass Effect: Andromeda.

At the end of Mass Effect 4's trailer is a shot where the Mudskipper can be seen out of focus behind Liara's head. Unless time travel is somehow involved, it wouldn't make sense for an Angara to be in the Milky Way before the events of Andromeda. If Mass Effect 4 is set after Andromeda, however, it seems entirely possible that the two galaxies could have established a Mass Relay connection, allowing characters and new species from Andromeda to travel back to the setting of the original Mass Effect trilogy and meet old characters. This would mean Mass Effect 4 is set at least 600 years after Mass Effect 3, but less than 900 years after the original trilogy, assuming Liara has a normal Asari lifespan.

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Humans in Mass Effect can live to be around 150, while the same is true for Turians and Quarians. In special cases like the genetic modification of Miranda Lawson, however, these races can live significantly longer. In Mass Effect 2, Miranda explains that she's likely to live fifty percent longer than the average human.

Assuming Miranda represents the peak of human, Turian, and Quarian life-extension through genetic modification, this would make Tali, Garrus, and all of Shepard's human squadmates very unlikely to return in Mass Effect 4. Salarians only live to be around 40, though Mordin dies in many playthroughs anyway. The Geth are presumably biologically immortal, but Legion always dies in Mass Effect 3, as does Thane. EDI could also be biologically immortal, but the trailer implies Mass Effect 4 takes place after the Destroy Ending, which would have killed all synthetics. It took about 300 years for the Reapers to wipe out the Protheans, and with Javik claiming the survivors of the initial attack were "long dead" by the end, the Prothean lifespan is likely similar to a human's.

The best candidates for returning companions are the Krogan and Asari characters. There are four Krogan or Asari squadmates in the original Mass Effect trilogy. Wrex and Grunt are the Krogans, Liara and Samara are the Asari. In both cases, one character from each species is very young, while the other is far older. Wrex's dialogue in Mass Effect 1 about the aftermath of the Krogan Rebellions and his relationship with his father implies that he was alive at the time. The Krogan Rebellions took place from around 700 to 800 CE. Mass Effect 1 begins in 2183 CE, which would make Wrex over 1400 years old, and possibly older. In fact, there isn't much firm evidence to suggest that the Krogans can die of old age at all, especially with members of the species far more frequently dying in battle.

However, assuming that the Krogans do have some sort of biological clock, or at least factoring in the probability of death by other means, Wrex is likely out of the picture by the time Mass Effect 4 is set. Grunt, on the other hand, is a different story. Like Liara, he is very young - in fact, Shepard practically witnesses his birth in Mass Effect 2. It is also possible that, like Miranda, Grunt's unnatural origins could lead to a longer lifespan if Krogans have one at all.

The Asari lifespan is far more defined. Samara is already nearly a thousand years old in Mass Effect 2, which makes her survival as unlikely as any of Shepard's shorter-lived squadmates. Of course, Andromeda already heavily relies on the idea of cryogenic sleep, though it isn't clear why any of Shepard's squadmates would choose that over simply living their lives following the end Mass Effect 3.

Andromeda also introduces the Scourge, a mysterious energy field which defies modern science as understood in the Mass Effect universe. It seems to have some connection to dark energy, and in one cut Mass Effect 2 plotline, dark energy was going to be related to time manipulation.

It's possible that Mass Effect 4 does not, in fact, take place long after Mass Effect 3, but instead that the Andromeda Initiative somehow found a way to travel back through time and space using the Scourge, essentially linking the two galaxies at two different points in time.

That possibility might be a bit far-fetched even for Mass Effect, however, and introducing time travel is one surefire way to create plot-holes in future Mass Effect stories if it is not handled properly. This leaves Liara and Grunt as the only Mass Effect characters with the biological capacity to live at least 600 years after Mass Effect 3. The fact that Grunt can die in Mass Effect 2 and 3, however, could leave Liara as Shepard's lone link to the original trilogy. If the series is going to tell a new story, however, that sacrifice may be for the best.

Mass Effect 4 is in development.

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