WARNING: The following article contains spoilers for The Flash #83, by Joshua Williamson, Rafa Sandoval and Jordi Tarragona, on sale now.
The Flash continues to explore the nature of the Speed Force, with the latest issue turning the mystical power into perhaps the most dangerous force in the DC Universe. The Flash #83 sees Barry trapped by King Cold in Iron Heights as the Rogues run wild in Central City. Trapped in a power dampening collar, Flash is saved by Cold’s sister, Golden Glider, and taken to Kid Flash and Avery Ho, the Flash of China, as a show of loyalty.
Barry demands Glider removes his power dampening collar despite Kid Flash’s warnings. Once the collar is removed, he suffers a type of "Speed Force aneurysm" as he experiences a surge through time. Kid Flash saves him by replacing the collar and cryptically telling Barry the Speed Force was too dangerous to use. It isn't the first time the safety of the Speed Force has been brought into question, but this current run of The Flash seems to be aiming to definitively flesh out its dangers.
Since it was introduced during the '90s run of The Flash, the Speed Force has helped speedsters as often as it has hurt them. However recent runs have established it as downright deadly. Only Wally could safely navigate the Speed Force after he was nearly lost in it, only able to return due to his love for Linda Park.
But even with his mastery over the powers, Wally couldn't navigate the Speed Force without Linda to lead him home. When he lived in a timeline where she never existed, or after Flashpoint when the world had forgotten who Wally was, he appeared hopelessly lost in the Speed Force. Though Barry, too, has ventured into it on occasion in recent stories, it's always portrayed as incredibly dangerous, and he often has trouble moving around in it without being injured or lost.
Though Barry had been unable to use the Speed Force prior to his death in Crisis on Infinite Earths, The Flash: Rebirth established that Barry generated the energy for the Speed Force when he ran. But as Barry generated Speed Force energy by running, so too did Eobard Thawne, the Reverse-Flash; generating a Negative Speed Force. Possessed by this bizarre energy and accidentally atomizing Johnny Quick and Max Mercury, Barry would learn quickly that it was a ploy by Thawne to fool Barry into merging with the Speed Force so that Thawne could be freed.
The Negative Speed Force would return following DC Rebirth when Barry and Iris would be stranded in the future by Hunter Zolomon. The Negative Speed Force here would perverse Barry and turn him into a malicious shadow of his former self. Bary would eventually be freed of the Negative Speed Force when it was stolen by a former ally and lover, Meena Dhawan, who became the Negative Flash. Possessed by the Negative Speed Force and mentally controlled by Gorilla Grodd, she nearly aided in the destruction of Central City before defecting. Currently, Meena remains in Iron Heights with a power-dampening collar locking down the Negative Speed, and has tried to persuade Barry of the dangers of the Speed Force.
Most recently, Barry discovered that other forces threatened the very existence of the Speed Force. The Still, Sage and Strength Forces all threatened Barry by diluting his own powers. While all four Forces were active, this left Barry and his fellow speedsters much slower. Worse yet, it triggered the appearance of the Black Flash.
The Black Flash has been an ongoing threat to Speed Force users, appearing as a skeletal body clad in a black Flash costume. He's said to appear whenever a Speedster is destined to die but has also served as a guardian of the Speed Force. With the new Forces active, the Black Flash was changed and viewed them as tumors it had to excise. However, this brought about the return of Hunter Zolomon, who stole the Forces to bait out Black Flash.
In possession of all four Forces, Hunter was able to go toe to toe with Black Flash but risked destroying all the Forces forever in the process. However Flash was able to persuade Hunter by showing him how he had been betrayed by Reverse-Flash decades earlier. Zolomon would seemingly sacrifice his life to repair the broken Speed Force, but Barry and Black Flash were trapped inside and the Speedsters outside were affected by the implosion.
Now the Speed Force is so dangerous that even Barry cannot control it, and a powerless Flash must find a way to save Central City from the Rogues. But even if he gets it back, the question remains: what happened to the Speed Force? And is it ever going to be safe for the world to have even a single user of the power? This volume of The Flash has brought the power into question in a big way, and it looks like we may be working towards a final answer.