Multiple theories provide possible explanations for Oliver Queen's return to the Arrowverse in The Flash season 9. After months of speculation surrounding Green Arrow's chances of coming back for one last appearance, it was finally confirmed that the Emerald Archer will indeed be on hand for the final chapter in Barry Allen's story. Stephen Amell is slated to reprise his role as Oliver Queen in the ninth episode of The Flash season 9.
With The Flash - and presumably the Arrowverse as a whole - coming to an end, it's only logical that the show would find room for a guest appearance from character who started it all. But, Oliver is much more than just the hero who kickstarted the Arrowverse. He was personally instrumental in turning Grant Gustin's character into the superhero he is today. The role he played in Barry's journey makes him a natural fit for the final season. What's not clear, though, is how he'll be worked into the show since Oliver is dead. That being said, there's no shortage of available avenues the Arrowverse can take when it comes to bringing him back. Here's every theory on how Green Arrow returns to The Flash.
5 The Speed Force Uses An Oliver Queen Disguise
One of the most obvious pathways to an appearance from Amell in season 9 is the Speed Force. In earlier seasons, it served as an easy way for Barry to interact with faces from his past. Since its resurrection, the Speed Force has consistently appeared as Nora Allen, but its history of taking on the forms of people Barry loves has raised questions about it potentially using Oliver's face. While such a scenario could lead to a heartfelt moment for Barry, it would be disappointing for those hoping for the true Oliver Queen to return. It's also not exactly what's been promised either. When announcing Amell's involvement, The Flash showrunner Eric Wallace talked about "Grant and Stephen saving the world together again," which implies Amell will be doing more than just offering Barry advice as the Speed Force.
4 Oliver Queen Appears As A Hallucination
Curiously, Amell's guest appearance will coincide with the return of Bloodwork a.k.a. Ramsey Russo. Oliver and The Flash season 6 villain showing up in the same episode has raised some red flags, considering that Ramsey has the ability to generate hallucinations to fool his victims. And since both Diggle and Wally West are expected to appear alongside both returning Arrowverse characters in the ninth episode, it's been suggested that Bloodwork is behind all of it. From a narrative perspective, Bloodwork using Barry's relationships with Wally, Diggle, and Oliver to manipulate him does make sense. But for the same reasons that Oliver coming back as the Speed Force would be problematic, it's not the most appealing option.
3 Barry Travels Back In Time
Mistakes in previous seasons have taught Barry much about the perils of time travel, but that hasn't stopped the concept from continuously being used as a plot device in the series. For one reason or another, Grant Gustin's Barry Allen could find himself revisiting various moments of his life. If that's true, that would explain why Barry will meet Wally, Diggle, Oliver, and Bloodwork all in the span of one episode. If his situation is desperate enough, Barry may be willing to risk the consequences and seek help from Oliver while in the past. Going in this direction may be the only way that the Arrowverse can deliver a proper team-up between the Flash and Green Arrow in season 9.
If Barry really does go back to a time in Star City when Oliver was alive, what he'll find stands a good chance at being considerably different from what many remember about the past. It's important to note that the rebirth of the multiverse in "Crisis on Infinite Earths" resulted in numerous changes to Oliver's history as the Green Arrow. For instance, Moira Queen and Tommy Merlyn never died and Diggle had two children. The Arrowverse hasn't had an opportunity to explore Oliver's altered backstory, but a time-travel story with Green Arrow would make that a real possibility for season 9.
2 Barry Meets A Green Arrow Doppelganger
Since "Crisis on Infinite Earths," The Flash has avoided doppelgangers and alternate universes, but certain developments prove that they still exist in the multiverse. At the end of the crossover, it was indicated that the only other Earths in the new multiverse host characters from DC's other shows, but the Superman & Lois season 2 finale confirmed that Earth-Prime doesn't stand on its own. Because Superman & Lois takes place on a duplicate of Earth-Prime, it's not impossible that there's more of them out there. One could be a timeline where Oliver Queen is alive and active as the Green Arrow.
Boosting evidence for the alternate timeline theory is the apparent inclusion of Red Death. Set photos have made it clear that The Flash season 9 is bringing back Batwoman's Ryan Wilder (Javicia Leslie) as a gender-swapped Red Death. In the comic books, Red Death is an evil Batman doppelganger who steals the Speed Force from his Earth's Barry Allen and goes to war with the Justice League. And with these photos providing evidence of two versions of Batwoman fighting each other, it's become all the more likely that an alternate timeline story is happening. If so, it may be that The Flash season 9's Oliver Queen is from Red Death's Earth.
1 Oliver Queen Returns As The Spectre
Green Arrow did die in "Crisis on Infinite Earths," but it's possible that the Spectre lives on. Oliver evolved into the classic, cosmic entity from DC Comics in time for the final showdown with the Anti-Monitor in the crossover event. When he revived the multiverse, the Spectre's essence may have reconstituted itself elsewhere in the multiverse. Recent tie-in comics, which are canon with the Arrowverse, have pointed to this being the Spectre's fate after the Crisis.
As for how Oliver being the Spectre in season 9 can fit into the Arrowverse timeline, it wouldn't be a problem at all for Oliver to still be alive in some capacity. It's no secret that he'll reunite with Felicity in the afterlife in 2040, so The Flash is free to use the Spectre in a present-day storyline in a way that won't take back or undermine Arrow's series finale. Years after teaming up with Barry, he can still get his happy ending with Felicity. With that being the case, Spectre certainly can enter the picture in season 9. But, it would take a huge threat to the universe for someone on Spectre's power level to get involved.