Of all of the Arrowverse's heroes it's Barry Allen/The Flash who may be the one who has the hardest time dealing with the new normal of things post-"Crisis on Infinite Earths". Barry went into the red skies of "Crisis" fully expecting never to return - after all, not only did that future newspaper headline reveal the speedster's fate but it was confirmed by The Monitor as well. Barry was so convinced that he would not survive the event that he spent all of the first half of The Flash's sixth season preparing his loved ones for a life without him. Except, Barry didn't die in "Crisis". Earth-90's Flash sacrificed himself instead and in the end Barry survived when his friend and mentor Oliver Queen/Green Arrow did not. It's that loss that will have major impact on Barry going forward and according to The Flash showrunner Eric Wallace, the fallout of "Crisis" has only just begun.
In an interview with Entertainment Weekly, Wallace explained that the experiences of "Crisis" will send Barry on an emotional journey and, not only that, will be a key part of the return of Keiynan Lonsdale's Wally West/Kid Flash as there are deeper consequences of "Crisis" still to come.
“One would think the true fallout of ‘Crisis’ is the death of Oliver Queen and not having your mentor — you know, Obi-Wan is gone, Luke must rise up, become a hero — and that happens, don’t get me wrong, but that’s not the real fallout of ‘Crisis,’” says Wallace. “The real fallout of ‘Crisis’ has yet to be seen. That is the heart of our story, and that is the heart of what is going to lead Barry on a very emotional journey that he is not prepared for. That’s one of the things having Keiynan back as Kid Flash does for us: [It] directly addresses — because Keiynan will be in one of our episodes in ‘Graphic Novel #2’ — [and] is to help Barry deal with the real fallout of ‘Crisis.’”
It's unclear at this point what the consequences Wallace is referring to are, though one of the things we've seen about this new, rebooted universe so far is that while it looks and feels a lot like the Earth-1 reality the heroes were used to before "Crisis" (in Supergirl's case, looks and feels a lot like Earth-38) there are things that are different. Arrow's Star City is a crime-free place. Black Lightning is part of the new Earth-Prime. Supergirl is also part of Earth-Prime and, now, Lex Luthor is considered a hero. Batwoman has seen the surprising presence of a version of Beth Kane displaced from her own, pre-"Crisis" Earth. The Flash will also face some shifts. Some fans are already speculating that one of those shifts will be dealing with the realization that Team Flash's other Earth friends - such as Earth-2's Harrison Wells and Jesse Quick, Earth-19's Breacher and Earth-3's Jay Garrick - are gone entirely.
Of course, the consequences Wallace refers to could be even larger than that. When it was announced in December that Lonsdale would be returning, Wallace explained that Kid Flash would be back to help with a familiar threat that now has a not-so-familiar face.
"After working on his inner life in Tibet, Wally West, aka Kid Flash, is back to help Team Flash against a familiar threat... but one with a very new face! As always, it's a real treat having our Flash family member Keiynan Lonsdale back to play the youthful speedster, but what's different this time [is that] Wally has grown, along with his speedster abilities, too."
The Flash airs Tuesdays at 8/7c on The CW. The show's midseason premiere, "Marathon", debuts February 4.