Three Years Ago, "Invasion!" Set Up Oliver Queen's Crisis on Infinite Earths Sacrifice

Three years ago tonight -- on December 2, 2016 -- Oliver Queen said something to his sister that feels like it perfectly sets up what his character is now going through, and the sacrifice he will be compelled to make in "Crisis on Infinite Earths," which begins on next Sunday, December 8. For those who might not remember, December 2 was the Arrow episode of the "Invasion!" crossover, in which Earth-1 became aware of alien life for the first time, and The Flash asked Supergirl to come from Earth-38 to help them deal with an invasion by a group known as the Dominators.

The crossover marked the first time Supergirl was involved in a CW crossover event, since the previous season her series had debuted on CBS. And while there wasn't a Supergirl episode of the crossover (there was a moment at the end of that week's Supergirl which set it up, but that's about it), it was three episodes of TV that featured heroes from four series.

The Arrow episode was especially unusual, since it was the show's hundredth episode -- typically something that would be an opportunity to reflect on what the series had done in its first five years and the kind of show it had evolved into. They managed this by having Oliver Queen and some other characters familiar to Arrow fans kidnapped by Dominators and plugged into machines that simulated an idyllic world where they all got what they wanted. For Oliver and Thea Queen, that was a normal life and a wedding for Oliver, where Laurel was still alive and so were their parents. Oliver, John Diggle, and Sara Lance figured out that they were in a simulation and that they needed to figure out how to escape. Thea, though, wanted nothing to do with it.

Thea's life has never been an easy one, and one could hardly blame her for being tempted to stay behind when it looked like she had an opportunity at normalcy and a life with her parents. She tried to talk Oliver into staying behind, arguing that the simulation could be the opportunity for the sacrifices he had made as Green Arrow to finally be rewarded by the universe.

"I didn't make those sacrifices for a reward, Thea," Oliver told her. "I did what I did, because I thought it was right."

The episode would eventually end with another sacrifice, as Oliver (and Thea, and the rest) had to fight their way out of the simulation. As Oliver hung behind for a moment, surveying the fantasy world he was leaving, he was faced by numerous characters who were either dead or at least gone from the series, all giving Oliver words of encouragement. While they most likely will not be the same people, at least for the most part, it would not be surprising to see Oliver's funeral have a number of testimonials. The sci-fi trappings of the "Invasion!" episode -- those testimonials came in front of a giant, glowing portal -- also help set a tone for the "Crisis" to come.

And on that note of not doing it for the rewards?

"Mia feels that Oliver chose strangers; he chose to be a hero," Katherine McNamara, who plays Oliver's daughter Mia and will headline the planned Green Arrow and the Canaries spinoff, told ComicBook.com recently. "He chose, in her eyes, that fame and that success and that adulation over his family -- over being there for her, and he abandoned her for the life of a hero. And that brings a lot of resentment in her. And as she gets to see the reasoning behind his choices and really the world and the difficulty of the choices that he's presented with, that allows her to start to work through those issues....So, we get to see the two of them take on these issues together. But it definitely is a process."

That feels like the continuation of a theme, for sure -- and that seems to suggest that this week's episode, "Purgatory," might give Oliver and Mia the chance to hammer some of that out ahead of "Crisis" next week.

"Crisis on Infinite Earths" has loomed over the Arrowverse for years. The series premiere of The Flash featured an allusion to the hero disappearing amid red skies in the year 2024. During the original comics event, red skies were a sign of doom to come to a world during the Crisis. At the end of last season, a couple of things happened: The Monitor (LaMonica Garrett), who had appeared in "Elseworlds," reappeared and revealed that Oliver Queen was destined to die in the Crisis...and the future newspaper at STAR Labs rolled back the expected date of the Crisis from 2024 to 2019.

In the comics, Crisis on Infinite Earths centered on a battle between the combined superheroes (and even some villains) of the DC multiverse and an immortal, cosmic threat known as the Anti-Monitor. Like The Monitor, the Anti-Monitor will be played by LaMonica Garrett in the Arrowverse. As the Anti-Monitor destroys realities, he replaces their positive matter energy with antimatter, growing his own power and sphere of influence. He was eventually stopped by the sacrifices of several heroes, including The Flash and Supergirl, as well as the merging of multiple universes to save reality by becoming a single, unified timeline. Fans have long wondered whether the events of "Crisis on Infinite Earths" might bring Supergirl and even Black Lightning to Earth-1, where the rest of the series take place. The crossover will also feature guest appearances by Tom Welling as Clark Kent, Erica Durance as Lois Lane, John Wesley Shipp as the Flash of Earth-90, Johnathon Schaech as Jonah Hex, Kevin Conroy as Bruce Wayne, and Ashley Scott as The Huntress.

"Crisis on Infinite Earths" kicks off on Sunday, December 8 on Supergirl, runs through a Monday episode of Batwoman and that Tuesday's episode of The Flash. That will be the midseason cliffhanger, as the shows go on hiatus for the holidays and return on January 14 to finish out the event with the midseason premiere of Arrow and a "special episode" of DC's Legends of Tomorrow, which launches as a midseason series this year and so will not have an episode on the air before the Crisis.