[SPOILERS for those not caught up on The Flash ahead.]
Even more metahumans are heading to Central City in The Flash season 4, including DC Comics villains Brainstorm and Fallout. While it was initially suspected that The Thinker (Neil Sandilands) - the big bad for The Flash season 4 - was to blame for Central City's recent influx of metahumans, it has since been revealed that the Fastest Man Alive himself, Barry Allen (Grant Gustin) was technically the one responsible.
The Flash season 4 episode 'Luck be a Lady' not only introduced the supervillain Hazard to the Arroverse; it also revealed that the energy wave caused by Barry's return from the Speed Force to the everyday world struck a nearby bus full of passengers, all of which seemingly now have metahuman abilities. Team Flash has already battled and captured two of the individuals who were on that bus (the technopathic Kilg%re and luck-powered Hazard) and will cross paths with another in tonight's episode, 'Elongated Journey Into Night'; namely, Ralph Dibny aka. Elongated Man (Hartley Sawyer). Unfortunately, for Barry and his friends, there were more than three people on that bus - and now we know who at least two more of them are.
THS has gotten ahold of the character descriptions for the versions of Dominic Lanse aka. Brainstorm and Neil Borman aka. Fallout, respectively, that will soon appear on The Flash season 4. You can read those breakdowns below:
Dominic Lanse/Brainstorm -- Male, late 20s - late 30s, African American. A gregarious and good-natured meta-human who has the ability to read minds. His gift becomes a curse when criminal forces capture Dominic and want him to use his powers for evil. Think young Sterling K. Brown type......RECURRING GUEST STAR
Neil Borman/Fallout -- Male, 30s - 40s, Open Ethnicity. Neil a blue collar, likable, good guy just trying to make ends meet, but unbeknownst to him, he has radiation emitting meta powers that could cause the whole city to suffer a nuclear, catastrophic explosion. Neil is unaware that he is hurting people. Think Martin Freeman on "The Office".....PERFORMER MUST BE BALD.....POSSIBLE RECURRING GUEST STAR
The flashbacks to Hazard's life before her metahuman transformation - when she was just a regular, if rather luckless, person named Becky (Sugar-Lyn Beard) - in 'Luck be a Lady' did provide a quick glimpse at some of the other passengers who were on the bus with her, when Barry remerged from the Speed Force. However, since it sounds like Brainstorm and Fallout haven't been formally cast yet, it seems safe to assume that they were not among the passengers who appeared briefly onscreen or in the background of that episode. That said: probably best to not count on the real Sterling K. Brown showing up as Brainstorm, either (seeing as he's plenty busy with other projects, like the TV series This Is Us).
Like Hazard and Kilg%re before them, Brainstorm and Fallout will probably be introduced as baddies-of-the-week in separate episodes of The Flash season 4, before being captured and imprisoned by Team Flash. That's all part of The Thinker's master plan, however, as it's now been clearly established that he is amassing an army of metahumans to serve his own nefarious purposes. That also explains why Brainstorm is listed as being a recurring guest star (and Fallout as a "possible" returning player) on The Flash, since his first battle with Barry shouldn't end up being his last. In fact, he may go on to become a member of the Arrowverse's own Injustice Society.
The Flash continues tonight with 'Elongated Journey Into Night' on The CW.