A behind the scenes photo from the filming of the Arrowverse crossover event Crisis On Infinite Earths may have confirmed a popular fan theory that John "Spartan" Diggle will become a Green Lantern before the end of Arrow season 8. While the show itself has danced around the idea before, this photo may prove that the series' showrunners are finally following through on the idea.

Since 1970 and the release of Green Lantern/Green Arrow #76, there's been a tradition of Green Lanterns and Green Arrows teaming up in the comics. When Arrow set up John Diggle to become Oliver Queen's partner in crime-fighting early on in its first season, many fans speculated that Diggle might have been set-up as a substitute for the Green Lantern John Stewart. This theory persisted for several seasons, despite the characters having little in common besides their first names and a history of military service, though Diggle was a US Army Master Sergeant and Stewart a member of the United States Marine Corps.

Related: Arrow's Green Lantern Teases May Be Finally Addressed In Season 8

Twitter user ThemysciraBound posted a series of photos from the filming of Crisis On Infinite Earths which seem to suggest that the theory may finally be confirmed. The photos show several stunt doubles, filming a scene where the heroes are attacking the Anti-Monitor. John Diggle's alter ego, Spartan, is said to be among the heroes gathered for the fight, but his body armor and helmet have a darker green cast to them than usual. Indeed, it almost looks as if his regular uniform had been redone with green accents - a common trait of many of the costumes worn by Green Lanterns who forwent the usual Corps uniform in the Green Lantern Corps comics.

While this doesn't prove that John Diggle will become a Green Lantern as part of Crisis on Infinite Earths, the show has dropped a number of hints about the fan theory being correct over the course of Arrow season 7. When the Barry Allen of Earth-90 met the heroes of Earth-1 during the 2018 Elseworlds crossover event, he recognized Diggle and asked why he wasn't wearing his ring. Later that season, Team Arrow was introduced to Diggle's stepfather, US Army General Roy Stewart. This prompted speculation that, on another world, Diggle might have taken his stepfather's last name and become John Stewart.

Actor David Ramsey has remained tight-lipped about the possibilities, while acknowledging there have been talks about it happening since Arrow season 2. The photos are compelling evidence, but it seems unlikely the existence of a Green Lantern Corps in the Arrowverse will be confirmed before Crisis On Infinite Earths airs. However, if there were ever a time for the bearers of the most powerful weapon in the universe to reveal themselves to the heroes of Earth and induct John Diggle into their ranks, this Blackest Night would certainly be it.

More: Arrow: How John Diggle Really Is Green Lantern (But Only On Some Earths)

Source: ThemysciraBound/Twitter