Warning: The following contains SPOILERS for The Flash season 8, episode 18.

The long-teased idea that John Diggle would become the first Green Lantern of Earth-Prime in the Arrowverse was finally resolved in The Flash season 8, though Diggle ultimately didn't become a member of the Green Lantern Corps. This revelation was a disappointment for those who theorized that the destiny of the former vigilante and ARGUS agent lay in the stars. However, the decision was true to the character's history and personality and sets the stage for his upcoming Justice U series.

Played by David Ramsey across all eight seasons of Arrow, John Diggle is one of the most popular original characters created for the Arrowverse. Acting as the Little John to Oliver Queen's Robin Hood, the soldier turned bodyguard was a stabilizing influence on the Emerald Archer after his return to civilization. He eventually became Green Arrow's brother in spirit as well as his partner in crime-fighting and adopted the alias Spartan when he wasn't taking up the Green Arrow mantle for himself.

Related: Oh No, The Flash Just Set Up A Terrible Arrowverse Villain Twist

The brotherhood that grew between John Diggle and Oliver Queen resembled the friendship between Oliver Queen and Green Lantern Hal Jordan in the comics. This led some to theorize that John Diggle might become a Green Lantern in the Arrowverse, due to his sharing several character traits with the Green Lantern John Stewart. Arrow dropped several hints in this direction, such as the revelation that Diggle's stepfather was a man with the surname Stewart and The Flash of Earth-90 recognizing Diggle and saying "You're not wearing your ring," in reference to the trademark jewelry of the Green Lanterns.

How The Arrowverse Set Up Diggle As Green Lantern

Arrow Fadeout John Diggle finds Green Lantern Ring

The series finale of Arrow seemed to set John Diggle on the path to becoming a Green Lantern, with a strange box containing a glowing green object crashing to Earth near him as he was in the process of moving the last of his belongings from his home in Star City to Metropolis, where his family was already waiting for him. Diggle made several appearances across the Arrowverse after the Arrow finale, reporting that he had been having headaches and hearing voices ever since acquiring the box, but had not been able to open it a second time. This left the future of John Diggle rather confused, as Diggle consulted with his friends at STAR Labs and Wayne Enterprises regarding his physical condition and the box. His final appearance came in the Batwoman season 3 episode "Meet Your Maker," where Luke Fox's efforts to open the box proved ineffective.

Why John Diggle Doesn't Become The Green Lantern

The Flash Season 8 John Diggle Rejects Green Lantern Destiny as Reverse Flash Eobard Thawne Watches

John Diggle appeared in The Flash season 8, episode 18, "The Man in the Yellow Tie," visiting Eobard Thawne (Tom Cavanagh) in his cell in the ARGUS prison facility on Lian Yu. Having failed to find any answers with modern scientists, a desperate Diggle decided to turn to Thawne hoping that the mad scientist from the future might have some idea of what the box was. The gamble paid off, and the depowered Reverse Flash confirmed that he had heard of such cubes appearing to people with the potential to wield great power and change the future at turning points in their lives. Under Thawne's direction, Diggle was able to put himself in the right frame of mind to open the box again and was treated to visions of a thousand lives he could live. However, when he realized that all of those lives required him to abandon his wife and children, Diggle rejected the box and threw it away, where it vanished in mid-air.

Was Diggle Not Becoming The Green Lantern The Right Choice?

John-Diggle-NOT-Green-Lantern-Flash-Crossover

This decision seemingly closes the book on the possibility of John Diggle becoming a Green Lantern. While it was theorized that Diggle might star in the Green Lantern Corps series being produced for HBO Max and act as the point of view character for those unfamiliar with the mythology of the Green Lanterns, this idea always seemed like a poor fit for Diggle's character. While Diggle was always at his best as a relatable everyman whose stoicism was continually tested by the strange metahuman threats he routinely faced, the humor in having him cope with increasingly odd alien creatures as the Arrowverse Green Lantern would grow tiresome quickly. It also better fits his personality for him to act as a mentor to a team of young heroes, as he reportedly will in the upcoming Justice U series. Ultimately, Diggle's character is defined by his devotion to his family and, as he noted in The Flash season 8, "there is no power in the universe more powerful than the love I have for my family." It would be incredibly out of character for John Diggle to abandon his wife and children, even in the pursuit of a noble cause like being a Green Lantern.

More: How John Diggle’s Green Lantern Could Massively Expand the Arrowverse

The Flash releases new episodes on Wednesdays on The CW.