The Flash has multiple ways for Cobalt Blue to finally join the Arrowverse. Theories about how the villain will be introduced date all the way back to season 1. And though the Arrowverse has continuously held him back, the character’s live-action debut is now in sight.
After eight seasons, Cobalt Blue a.k.a. Malcolm Thawne stands out as the biggest Flash villain the Arrowverse series has yet to use. Over the years, it’s worked in a long list of characters associated with not only Barry Allen, but also the other heroes who have carried the Flash mantle in DC Comics. The CW series has pitted Barry against everyone from Mirror Master to Gorilla Grodd. He’s fought top-tier villains like Reverse-Flash and lesser-known members of his rogues’ gallery, such as Rainbow Raider and Bug-Eyed Bandit. One character in particular that’s thus far been avoided by The Flash is Cobalt Blue, a villain who certainly posed his fair share of problems for Barry and his friends in the comic books.
While The Flash showrunner Eric Wallace hasn’t outright said that Cobalt Blue is coming to the show for the final season, it’s no secret anymore that the character is on his way to the Arrowverse. The series made that plain in the season 8 finale, where the post-credits scene unveiled a mysterious blue crystal in a lab in 2049. Obviously, this is the talisman that will give Cobalt Blue his comic book powers. Furthermore, Wallace admitted that “hardcore comic book fans know what’s coming”, which all but confirms Cobalt Blue’s presence in The Flash’s final season. What’s not been revealed, though, is how The Flash will bring him into the fold. For now, that’s a major season 9 mystery. However, there are plenty of ideas on how he could be used. Here’s every theory on how Cobalt Blue joins the Arrowverse.
Cobalt Blue Is Barry Allen’s Secret Brother
Theoretically, The Flash could use Cobalt Blue’s comic book origin. In the comic books, it was explained that unbeknownst to Barry, he has a long-lost twin brother named Malcolm. Somehow, they were separated at the hospital at birth, with Barry nor his parents ever being aware that Barry’s twin survived childbirth. After being taken away and raised by gypsies, Malcolm lived a sad childhood. Years passed, and Malcolm learned about his brother’s existence and his dual life as the Flash. This caused a deep feeling of resentment to grow within Malcolm which later contributed to his transformation into Cobalt Blue.
What set it off was the discovery that his adoptive parents had a special ability called the Blue Flame, which is fueled by negative emotions. With this knowledge, Malcolm poured all of his hatred for Barry Allen into a talisman connected to the Blue Flame and used it to become a super-powered villain. As Cobalt Blue, Malcolm sought revenge on Barry and caused chaos in the speedster’s life.
Of course, taking this route and revealing that Barry has a secret brother would be a risky move for the series, which is one reason why The Flash may avoid Cobalt Blue’s comic book origin. Plus, there’s the notion that the show has already done a version of this story. Savitar, the Barry Allen time remnant abandoned and forgotten by Team Flash, bears strong similarities to DC’s Cobalt Blue.
Cobalt Blue Is Eddie Thawne From An Alternate Timeline
It’s long been speculated that since making Cobalt Blue Barry’s brother would be narratively challenging, The Flash may retcon Eddie Thawne into Cobalt Blue instead. Going in that direction would make sense to a certain degree, especially since a fundamental part of the DC Comics character is his connection to Eobard Thawne. Like Malcolm in the DC Universe, Eddie is a confirmed ancestor of the Reverse-Flash. It’s possible that Eddie truly is the Arrowverse’s Malcolm Thawne, albeit with a different first name. If so, it could be that while Earth-Prime’s Eddie avoided becoming his comic counterpart, the Eddie of a different timeline didn’t. Since Superman & Lois confirmed that duplicate Earths are still part of the equation after the Crisis, The Flash can technically still do alternate universe storylines and introduce a new version of Eddie Thawne. This would allow The Flash to make Eddie into Cobalt Blue without ruining the season 1 character’s heroic ending.
Cobalt Blue Is A Second Thawne Ancestor (From The Future)
Per The Flash's season 8 finale's tease, the show's interpretation of Cobalt Blue may not be Eddie Thawne or Barry’s secret brother. Instead, The Flash could introduce a new Thawne ancestor from a different point in the timeline. Specifically, he could be a character tied to Bart and Nora’s Arrowverse stories. In fact, that may have been what The Flash was hinting at when it revealed that the blue crystal is in a lab in 2049. Whoever Cobalt Blue is, he may be an enemy of either a middle-aged Barry Allen or his adult children. If he becomes the new host of the Negative Speed Force, as the finale implied would happen, Malcolm Thawne could travel back to the past and challenge the Scarlet Speedster in his prime.
Season 1’s Singularity Transformed Eddie Into Cobalt Blue
Another theory about Cobalt Blue explains that Eddie Thawne actually survived the events of the season 1 finale. After Eddie’s death, his corpse was sucked into the singularity. Similar to how Deathstorm turned out to be a previously unseen consequence of the singularity, The Flash could do the same with Eddie and reveal that the energy from the black hole transformed and revived his body, thus giving him new abilities and the means to become Cobalt Blue. As for where he’s been all these years, it could be that he’s been lost in space or in the timestream, fighting to make his way back. If what happened altered his personality, Eddie could turn into a full-fledged villain. The fact that his sacrifice did very little to end the threat posed by Reverse-Flash could also help push him down a dark path.
Arrowverse Reversed Eddie Thawne’s Death With Time Travel
The Flash season 8 played with the idea of Nora and Bart potentially changing the past when they went back to 2014. Additional visits to an earlier point in Central City’s history – whether it be with them or a different time traveler – could result in Eddie’s death being undone. Perhaps in the interest of stopping season 1’s Reverse-Flash from being erased, a character could save Eddie and set his Cobalt Blue story in motion. Being taken out of the timeline and then realizing that Barry married Iris instead of him could be what the show needs to give the character a proper villain arc. That could work well for the show, as jealousy over Barry’s happiness is integral to who Cobalt Blue is as a character. By leaning in this direction, The Flash can ensure that it does justice to the DC Comics villain in season 9.