WARNING: The following contains spoilers for The Flash #752, by Joshua Williamson, Howard Porter, Hi-Fi and Steve Wands, on sale now.
While the Reverse-Flash might be the most hated villain in the Flash's rogues gallery, he might be Barry Allen's only hope of defeating his latest foe, Paradox. In The Flash #751, Iris West discovered -- thanks to Commander Cold's files from the 25th century -- that Eobard Thawne, the Reverse-Flash, successfully took down Paradox in that time period. While Thawne has never really been a force for good, he was the only person who was able to put a stop to Paradox's rampage in the future.
Despite this knowledge, Barry kept fighting Paradox, even engaging him one-on-one when he had no hope of defeating his powerful adversary. By the end of that issue, Paradox had beaten the Flash, and the Scarlet Speedster woke up in a place that looked a lot like heaven. Thankfully, Barry Allen isn't really dead -- he's just trapped. And in The Flash #752, Barry learns where he really is and makes the impossible decision to team-up with his worst enemy to defeat Paradox.
Soon after waking up in what appears to be some kind of Speed Force afterlife, Barry Allen realizes that his idealistic heaven is nothing more than a construct created by Paradox. Next, Barry escapes this fake reality, only to discover that he is trapped in a Speed Force "hell." The superhero is actually prisoner ya pocket dimension outside of time and space where Paradox himself was once trapped. Thankfully, there are remnants of technology left behind by others who found themselves in this dimension. With this equipment, Barry is able to build himself a time armor and construct a cosmic treadmill from scratch.
This treadmill is not only his means of escape from his hellish prison, it also serves as a time machine to go back to a very specific moment from his past. As Barry comes to realize in The Flash #752, there is simply no hope of him defeating Paradox on his own, and he must do the unimaginable by joining forces with Eobard Thawne.
However, the Reverse-Flash isn't exactly a man that is easy to find. Thanks to his past experiences, as well as Paradox's recent arrival, Barry is all too aware of the dangers of playing with time. The last thing he wants to do is go looking for Thawne anywhere in time -- if he does that, he'd risk creating another paradox, or something as bad as another type of Flashpoint reality.
For that reason, Barry Allen chooses the only time in the past that he knows he can find Thawne with absolute certainty: the night the supervillain killed his mother. The night of the death of Barry's mother is an important moment in his life, and in Flash mythology. It's an event that defines his character, as well as his history in the modern era.
When Barry went back to this moment the first time in 2011's Flashpoint, he saved the life of his mother and ended up creating an entire alternate reality because of it. The only way to restore reality, and the timeline itself, was to undo this change and ensure Nora's death. Therefore, going back to that moment will surely prove extremely difficult for Barry. Not only must he do something incredibly hard already -- convince his ultimate nemesis to join forces with him -- he must also sit back as the villain proceeds to kill his mother.
It's interesting that Barry is fueled by his need to prevent the creation of another Flashpoint-like event, but that he goes back to the very point in time where he created it in the first place. However, he will surely have to be careful this time to ensure that nothing changes -- especially the death of his mother.