Despite being a doppelganger, The Flash’s Jay Garrick (John Wesley Shipp) coexists with Barry (Grant Gustin) and all the others on Earth-Prime. Before “Crisis on Infinite Earths”, Jay was a resident of Earth-3 and one of many alternate timeline characters who were thought to be unfortunate casualties of the event. But long before his return to the show, The Flash showrunner Eric Wallace explained that both Jay and Joan Williams (Michelle Harrison) survived.
Before the Crisis, the existence of limitless Earths in the Arrowverse allowed for the shows to utilize multiple different versions of existing characters. Because of this concept, Shipp was able to reprise his role as the Barry Allen he portrayed in 1990’s The Flash series. He’s also been Earth-1’s Henry Allen (Barry’s father) and Earth-3’s Jay Garrick, who is a version of Henry who became the Golden Age Flash. However, the days of doppelgangers popping up in the Arrowverse supposedly came to an end when Oliver Queen rebooted the multiverse and merged timelines to create Earth-Prime. After that, it was assumed that there would only be one version of each character. But, there are exceptions to that rule, one of which being Jay Garrick.
Since Jay is a doppelganger of Henry, it would have made sense if he was dead in the post-Crisis timeline, but Jay's return in The Flash season 7 confirmed that the Crisis didn’t end his story. The Flash provided no explanation for how he’s living in Keystone City, but his survival can most likely be attributed to Henry’s death in The Flash season 2. Since both of Barry’s parents are dead, there are fewer obstacles to Jay and Joan existing on Earth-Prime in their place. Since they don’t have to share the same time and space with Henry and Nora Allen, it is possible for both Jay and his wife to continue having a presence on The Flash.
This fits with what Arrow did with Laurel Lance (Katie Cassidy). On Earth-Prime, there were two versions of Laurel, but only one is currently alive. The Black Siren interpretation of the character from Earth-2 is able to be Earth-Prime’s Laurel since the original died. Batwoman explored the issues of doppelgangers existing together by introducing one after the Crisis. The series revealed that because this can’t work on a long-term basis, one will eventually be erased from the timeline. Since Henry is already dead, Jay apparently doesn’t have this problem.
Further adding to the unique nature of Jay’s Arrowverse character is the fact that Shipp now plays two versions of Jay in The CW’s DC multiverse. Stargirl, which is set on the post-Crisis Earth-2, had a Jay Garrick who served as a member of the original Justice Society of America sometime in the show’s history. So far, he and Earth-Prime’s Jay Garrick appear to be identical, at least in terms of their costumes and personalities. With Shipp’s characters continuing to be important to the Arrowverse’s future, the potential exists for several more adventures with the Crimson Comet on the small screen.
The Flash releases new episodes on Wednesdays on The CW.