Having escaped the 31st Century into the Speed Force, Bart Allen finds himself sent back to the 19th century and into the presence of Maxwell Crandall; The Windrunner. Bart isn’t simply there as Kid Flash though, the Speed Force spit him out as the Black Flash. His warnings go unlistened to though, and Max touches Bart and dies immediately, his speed absorbed into Bart who bounces forward.
In the 1940’s Bart emerges again to find the deceased body of Jay Garrick, who never received powers from the heavy water. Bart cradles the body of the first Flash and the Speed Force energy flows into him and sends him further forward. This part actually helps my theory on the big change in history that created the Flashpoint universe.
In the not so far off future Bart emerge again, this time at the grave of Wally West as Iris mourns him. This is enough to get Bart to push away from it, and actually try and outrace it.
Shedding the Black Flash mantle as he approaches the Speed Force, Bart comes up behind Barry and tries to get his grandfathers attention. Bart understands his role in all of this, and how he’s a conduit for the Speed Force meant to empower the Flash to save everything. Bart becomes the White Flash, the living embodiment of the Speed Force, and then his form goes away.
Bart is gone, but Barry has the power he needs to save the world thanks to Bart’s collection of the speedsters.
