Those who have seen Season 3 of The Flash know that Barry was the big bad, as it were, although not exactly in the sense that Grant Gustin believes it to be. While Savitar was literally a future-duplicate of Barry Allen, Gustin makes the argument that the modern-day Barry Allen was the actual big bad in The Flash's third season, and he explained how while talking about Season 4's lighter tone at an SDCC roundtable that CinemaBlend's TV Editor Nick Venable attended. In his words:
That was always the goal for our show was we were going to be the lighter, funnier show. And you know, sometimes storylines just take you where they take you. I think just because of all the time travel that Barry Allen did, and all the repercussions it had, it took us down the "Flashpoint" road, if you will. We really didn't do "Flashpoint" for long, but we dealt with the repercussions for an entire season. Barry wasn't only the big bad at the end of the year, but he was kind of the villain of the season because it was his fault that everything happened. So we're going to get back to our roots a little bit, and because of this experience in the Speed Force, Barry's able to let go of things and move on, and he's able to help the team move on, and the show can get back to its original roots where Barry enjoys having these powers and has fun, and the whole team has a little bit more fun.
Grant Gustin has a point, as the Arrow-verse did and still will be coping with the timeline-altering decisions Barry Allen selfishly made when he created Flashpoint. Cisco's brother is still dead, Diggle's daughter is a son now, and Julian Albert made his way to Central City to have the adventure of his life. (Even if he won't be back for more.) Add that to the fact that Barry essentially created his greatest enemy to date, one who made life even more miserable for all of Team Flash, and Barry Allen is certainly a strong candidate for the greatest villain the series has ever seen.
Luckily, it sounds like Barry's former depression over his actions will largely disappear, as Gustin adds The Flash will look to put the dark and dismal past behind everyone in Season 4. It sounds fast, sure, but with all the stuff that transpired throughout the season, including those sacrificial final moments, it seems understandable that The Flash wants to take it easy on Barry following his extended stay in the speed force. Considering the recent reveal that Barry will emerge from the experience a little rattled and off his game, it's only logical characters like Cisco don't try to disturb the newly formed status quo with the "You basically killed my brother and ruined Caitlin!" argument so fresh into Barry's return. Especially when a lot of that was already addressed in the prior season anyway.
Gustin mentioned that making Barry the villain (of sorts) led to a darker Flash season than the previous two, and he indicated Season 4 will be a return to lighthearted storytelling. That's good to hear, as everyone else's current situation looks far from pleasant: Joe is depressed, Cisco and Wally are power-struggling in the absence of The Flash, and Iris is trying to hold the pieces together even though she's just as sad, if not more so. Even if things turn more optimistic than they have any right to be, it'll be good for fans of The Flash to shake off the narrative darkness The CW's Arrow-verse typically reserves for, well, Arrow.
The Flash will return to The CW on Tuesday, October 10th, at 8 p.m. ET. Those eager to see the hottest shows of the fall season to watch out for should definitely check out our fall premiere guide. Anyone still needing a new or return show as a summer distraction can still visit our summer premiere guide.