Supergirl's third season has introduced a new version of the fan-favorite DC Comics team "The Legion of Superheroes" to the Arrowverse - and have they also brought The Great Disaster with them? The arrival of the League has many of the same pros and cons as they historically had on the printed page. On the one hand, more sexy young heroes wrapped up in romantic melodrama for a TV superhero brand that thrives on exactly that - on the other hand, time travel... and all the potentially plot-breaking headaches that come with it.
For those just joining us (or who forgot any of this was going on during Supergirl's extended Winter break) The Legion are a team of twentysomething do-gooders from the 30th Century whose time-displaced spacecraft was discovered on the bottom of the ocean with its passengers in stasis-pods and under the protection of onetime Supergirl love-interest Mon-El, who reveals that he was zapped into the far-future by the events of last season's finale and has spent seven years (though only a few months "our time") helping his new pals restart the tradition of costumed-heroism following the example of Kara herself.
Unfortunately, that seven year time difference proved long enough for him to fall in love with and marry fellow Legionnaire Imra (aka "Saturn Girl") - creating an understandable but inconvenient emotional distraction for Supergirl right when she needs it to battle new villainess Reign.
The Problem Posed By The Legion of Superheroes
But while emotional complications will always end up being the primary focus of a character-driven weekly series, the temporal twists that The Legion's very presence in the 21st Century creates are nothing to sneeze at, either. One of the reasons that the characters (though beloved by many fans) have so often found themselves forcibly disappeared from DC Universe continuity is that the existence of time-travel as a plot conceit and thus characters ostensibly from the future being able to visit the present inevitably raise the issue of how anyone fails to see certain serious events coming. After all, there being a future DCU for The Legion to have come from not only means that whatever world-ending crisis Superman etc. might be dealing with at the moment was thwarted, it logically follows that the Legionnaires might be able to tell them how it was done.
Every sci-fi/fantasy property with a time travel element eventually has to find a way to handwave this sort of problem, usually with variations on the butterfly-effect theory as popularized by Ray Bradbury in A Sound of Thunder, i.e. changing the past even minutely can throw the entire future into total chaos (see also: Back to The Future). But the DC Universe tends to favor something a little more concrete and, for lack of a better word, "epic", and the return of Supergirl saw the Arrowverse Legionnaires confirm that the tradition will continue there as well. They don't know how Supergirl eventually overcomes Reign because all record of Earth's prior history (and also art, culture, etc) was wiped out by a "third-degree extinction phenomenon" in 2455. Conceptually, devout DC fans were likely all thinking the same three words: The Great Disaster.
What The Great Disaster Could Mean For Supergirl Season 3
The Great Disaster, like many of DC's favorite go-to "big idea" concepts, is drawn from a slew of highly creative but (paradoxically) not enormously popular or well-received series and characters launched by Jack Kirby after his high-profile departure from Marvel in the early 1970s, of which Darkseid and The New Gods are the most well known but which also included apocalyptic sci-fi yarns that would later be repurposed as the basis for the early-2000s lead-in miniseries' that set up the Infinite Crisis crossover. Specifically, the future world of "Earth AD" as depicted in Kirby's Kamandi: The Last Boy on Earth, a kind of gonzo-pastiche of Planet of The Apes which depicted a semi-feral human child navigating a ruined Earth ruled by warring tribes of evolved humanoid-animals - a bizarre future supposedly unleashed by an only vaguely-remembered calamity called The Great Disaster.
Exactly what The Great Disaster was (and what was so "great" about it) was initially left somewhat vague, another textbook example of Kirby's surprisingly often-proven dictum that a catchy name and a compelling result were worth more to storytelling than detailed mechanics. Generally, the end of the world was said to have been caused in part by an "energy wall" called The Vortex (it's best not to think about how a wall can be a vortex or vice-versa) with a drug called Cortexin being tested on an oddly-diverse set of lab animals explaining the various evolved animal tribes. But as later writers revisited the Kamandi story and worked to "square" what was originally an alternate-timeline future with the post-Crisis unified continuity of the DC Universe, multiple possible "Great Disasters" emerged - including one involving a deadly gene-scrambling virus called The Morticcocus that was connected to The Legion.
Indeed, Supergirl's version of The Legion were also talking about deadly future legacies tied to their literal blood as the (belatedly-explained) rationale for their time-jumping mission itself, but it apparently has a connection to a different part of DCU lore: they're carrying the key to the future surviving the alien marauders known as The Blight. But with a "void in time" now introduced as an official part of The Arrowverse (albeit in the alternate timeline that Supergirl still inhabits) it would appear that the first stirrings of a Great Disaster may indeed be in the offing. If so, it could be Supergirl's chance to define not just the immediate world of its characters but The Future in a very real and wide-reaching sense, opening up whole new worlds - perhaps literally - of stories to come.
Supergirl continues Monday, January 22 with ‘Fort Rozz’ on The CW.