The Flash season 9’s villain setup makes it possible for a season 1 fan theory to finally come true. The post-credits scene in The Flash season 8 finale laid the groundwork for Cobalt Blue to join the Arrowverse. Cobalt Blue is the brother of Barry Allen and one of the biggest Flash villains still missing from the Arrowverse.
Following Reverse-Flash’s defeat, the show laid down its first building block for a Cobalt Blue story. When Team Flash was discussing the Negative Speed Force’s next avatar, attention shifted to a lab in 2049 where a blue crystal was seen glowing. The crystal was recognized as the talisman that houses the Blue Flame. In DC Comics, this is the artifact that supplies Cobalt Blue a.k.a. Malcolm Thawne with his mystical powers. The character’s name wasn’t mentioned, but The Flash showrunner Eric Wallace has erased any lingering doubts about Cobalt Blue entering the picture in The Flash season 9. Based on his comments, the subject of the tease is indeed the character fans think it is.
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The promise of Cobalt Blue showing up in The Flash means that the series can pay off a season 1 theory about Rick Cosnett’s Eddie Thawne. Back when it became clear that Iris’ boyfriend was distantly related to Reverse-Flash, it was speculated that Eddie – who doesn’t exist in the comic books – was secretly The Flash’s take on Cobalt Blue. This theory, which obviously never panned out, was based on the fact that Eddie and Cobalt Blue are ancestors of Eobard Thawne in their respective continuities. With Cosnett developing a recurring presence on The Flash amid the show’s approaching Cobalt Blue storyline, the actor suiting up as the DC Comics
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