Plans for The Flash season 9 reveal that the CW series is retconning two different villains from Arrow. In spite of a significantly shorter episode count, The Flash's final season is expected to offer more than its fair share of villains for the Scarlet Speedster to fight during the final chapter of his Arrowverse story. Numerous foes from Barry's rogues' gallery - plus two more with Arrow connections - will be clashing with Team Flash when the series returns.
Thanks to the rebirth of the multiverse and the creation of Earth-Prime in "Crisis on Infinite Earths," various Arrowverse shows have been granted the luxury of offering new takes on existing Arrowverse characters. The Flash, for its part, has taken advantage of the multiverse reboot on multiple occasions via new incarnations of several Arrowverse characters. Since season 6, The Flash has adjusted the backstories of villains like Pied Piper and Ultraviolet while also introducing post-Crisis versions of Rainbow Raider, Turtle, Godspeed, and more.
Murmur & Captain Boomerang Are Both Arrow Villains
Two more villains are getting the post-Crisis treatment in The Flash season 9. Richard Harmon has been cast as Owen Mercer, known in DC Comics as the second iteration of Captain Boomerang and the son of the original villain to use the mantle. In Arrow, Oliver Queen clashed with Digger Harkness' Captain Boomerang numerous times before the character's demise at the hands of Malcolm Merlyn in season 5. The comic book character was a prominent Flash villain, but Arrow's interpretation of him only fought Barry once, which was during the first crossover between the two shows.
In addition to its new Captain Boomerang, The Flash seems to be rebooting Murmur, a villain introduced on Arrow as a former Iron Heights inmate who went over the edge after being put behind bars for a false confession. Later, the character stitched his mouth shut and went down the path of a serial killer. What Arrow did with him was essentially a loose interpretation of the comic concept, whereas what The Flash trailer showed at the 0:22 mark looks to be a much more comic-accurate adaptation of the villain, who is actually a member of the Rogues team that fights Barry Allen.
What Murmur & Captain Boomerang Mean For The Flash Season 9
With both Captain Boomerang and Murmur being villains with closer ties to Barry than Oliver in the comic books, it certainly makes sense that The Flash has picked them to be retconned in the post-Crisis timeline. As for what it is exactly that the series has in store for them, there's a chance that both will be a part of the same story. According to a synopsis for season 9, Barry will have to contend with a new team of Rogues. As Rogues in DC Comics, Captain Boomerang and Murmur would be strong candidates for membership. If so, Barry may have to find a way to prevail against both at the same time.