WARNING: The following contains spoilers for Justice League #20, by Scott Snyder, Jorge Jimenez, Alejandro Sanchez and Tom Napolitano, on sale now.
There are few things in comics quite a delicate and constantly manipulated as the DC Universe's timeline. It was little surprise to longtime fans, then, that when Barry Allen went back in time to save his mom, Nora, from death, he broke not only the timestream, he inadvertently gave us the dystopian future that came to be known as Flashpoint.
It was a dark and perilous alternate reality, filled with death and some of the most morose DC heroes we've ever seen. Thankfully, Barry quickly learned the error of his ways and was able to fix most of the damage -- or so we believed, until it the later revelation that Watchmen's Doctor Manhattan actually interfered, leading to the New 52 Universe. It's a bit of a surprise, then, to learn in the latest issue of Justice League that the Flash might have eventually not just undone his timeline-altering actions, he may have somehow actually succeeded in his original goal -- and then some.
Flashpoint saw the Amazons and Atlanteans go to war, introduced a gaunt Superman who was locked away and tortured, and a Thomas Wayne who became a savage, gun-toting Batman. In this reality, the lines were blurred between heroes and villains, and Barry quickly realized that no life, even that of his mother, was worth this amount of damage to reality. As a storyline, it was as intriguing and provocative an option for a hero to have, but the ultimate lesson is that you just cannot mess with the past without having some sort of repercussion on the future.
Unless you're mucking about with timelines from the Sixth Dimension.
The introduction of the Justice League's future selves came with the revelation that the dimension they're calling home is actually the engine room for the Multiverse, where you can create or destroy realities. That's why the League's is there, after all, as they attempt to learn how they can use it to fix their currently fracturing reality. In Issue #20, as the present-day Barry peers into the control room, his mind is blown when his future self and the White Lantern, John Stewart, reveal exactly how this paradise has been created.
The League has become the architects of the Multiverse. White Lantern uses the Life Entity to create worlds and seed them out into the Multiverse, after which Barry places them into the timestream at the appropriate points. He does so by carefully traversing the space-time continuum to find the perfect spot for their existence to spring up, a job that has been made all the more easier as he's now able to access and manipulate time without breaking the timestream.
Future Barry indicates that this skillset, catalyzed by fiddling with the Speed and Still Forces, has allowed him to create a utopia for everyone by collapsing Hypertime (essentially a network that finds every single possible DC reality existing at once) with no repercussions. This allows him to reset things in the timestream and alter events without consequence. As a result, he's saved Nora and everyone who died in his life, thus giving Barry the Flashpoint moment he always wanted. All his loved ones are safe, sound and alive.
This has allowed the Allen legacy to grow, and more, makes future-Barry nothing short of a god, with no restrictions in terms where or when he can travel. He can repair and improve the Multiverse as he sees fit, which leaves the younger version of himself in a combination of awe and envy. After all, young Barry is finally seeing his dream come true, a moment that will undoubtedly leave its mark on his psyche, for better or for worse, when the modern day League inevitably leaves the Sixth Dimension.