When The Flash season 4 begins, the titular hero will actually be out commission, still stuck in the Speed Force prison he entered after defeating the evil Savitar at the end of season 3. Fans who have watched the show know that the Speed Force is an entire reality unto itself - one where the rules of time and space are very different.
Months will have passed in our reality between when Barry Allen sacrificed himself to the Speed Force in season 3, and where season 4 picks up. That leaves a big looming question as to how time is passing, comparatively, for Barry within the Speed Force - and how that new relatively changes the The Flash, both physically (new powers?) and mentally.
So... How Much Time Passes For Barry In The Speed Force when The Flash season 4 begins? We already have some big clues...
During Comic-Con 2017, we here at Comicbook.com actually got to speak The Flash star Grant Gustin, who addressed this exact issue of how Speed Force time relativity will fundamentally change Barry Allen.
As Gustin revealed to us, The Flash season 4 (thankfully) won't be using up time making us traverse through more episodes of surreal Speed Force reality; we'll be getting Barry back soon into the new season, with the intrigue being what has happened to the young superhero as a result of being in that other dimension:
“We’re not necessarily going to see Barry’s experience in the Speed Force," Gustin explained. "We’ll see kind of the effects that the Speed Force has had on Barry, and he’s been in there six months real-time. I suspect the Speed Force is kind of nonlinear with time, so Barry has experienced his entire life from start to end infinity times over since he’s been in there.”
As for what that warped sense of time has done to Barry, Gustin further revealed that it will create a much wiser and more powerful Flash - even if Barry himself doesn't realize it:
“He’s going to have kind of an awakening when he comes out. He’s going to have some knowledge that he probably doesn’t even quite understand yet. He’ll also be little scrambled; He won’t really be himself the first time we see him.”
While on the one hand it sounds like The Flash will milk its usual amount of sappy drama out of Barry being back and yet 'not back' (bet that's a scene of dialogue between Team Flash at some point), it does offer an opportunity for something The Flash sorely needs...
Since the beginning, The Flash has been teasing the idea that, one day, Barry Allen evolves into a truly great superhero - one whose loss during a great crisis event makes him a worldly martyr. Indeed, at various points throughout the series, there are references made to the hero Barry becomes , form both allies who have fought with him in future battles, as well as those future enemies he's bested.
However, in the first three seasons of The Flash, we've basically gotten to know a version of Barry who is both inexperienced and dangerously flawed in his approach to heroism. He still requires some pretty extensive coaching on using his powers, and more often than not, has barely survived battle, after making some very careless mistakes.
When Barry returns from the Speed Force, The Flash will have a perfect opportunity to finally reveal his full-fledged powers, without a lot of trial and error training. Let's hope the show capatalizes on that opportunity, because as you can read below, it could also offer fans a cool new power set for The Flash that they haven't seen before:
Supergirl will premiere on October 9th at 8 p.m. ET/PT on The CW, followed by The Flash in the same timeslot on October 10th. DC's Legends of Tomorrow will follow The Flash this season, airing at 9 p.m. on Tuesdays. Arrow has moved to 9 p.m. on Thursdays.