Spoilers ahead for the sixth episode of The Flash Season 5, called "The Icicle Cometh."
The Flash finally delivered an episode that expanded on Caitlin Snow's family history and introduced her dad, but the Snow family drama wasn't the only source of excitement from "The Icicle Cometh." The episode may have also dropped a big clue that reveals why crossover villain Dr. John Deegan targets Barry and Oliver for the switcheroo that turns Barry into Green Arrow and Oliver into The Flash. Let's break it down.
As many Arrow-verse fans know by this point, Dr. John Deegan will be an Arkham Asylum doctor who rewrites reality to swap Oliver and Barry's lives, with Barry and Oliver as the only ones who realize that something is very wrong. The rest of the characters seem to be going about business (and relationships!) as usual, which points toward Deegan deliberately targeting the heroes of Central City and Star City.
The big question was how and why Deegan would target these two men when at least Barry's identity as The Flash is still supposed to be a secret. Well, "The Icicle Cometh" may have revealed a connection between Barry as The Flash and Dr. Deegan in Arkham, and it's all thanks to Caitlin's dad.
When Caitlin, Barry, and Cisco travelled to a Tannhauser site in the North Pole in search of Caitlin's dad, they discovered him living an isolated (and icy) life. They were also surprised to learn that Thomas Snow knew Caitlin's friends' names. Thomas dropped some recognizable names in his explanation, saying this:
Depending on when Thomas Snow was in contact with these scientists throughout the years, he may have been communicating with Eobard Thawne doubling as Harrison Wells, and Thawne undoubtedly wouldn't have gone out of his way to protect Barry. DC Comics fans may also recognize the name "Louise Lincoln" as the identity of a non-Caitlin Snow version of Killer Frost. The most significant name there with regard to the crossover, however, is Victor Fries.
If the Victor Fries that Thomas Snow is referring to became the villain known as Mr. Freeze, then he could very well be in a position to give away Barry's identity and significance to Dr. Deegan in Gotham. After all, Mr. Freeze is an iconic villain of the Bat-family, and the crossover is going to be positively batty even without the Dark Knight. The Joker could even be in the mix. Why not Mr. Freeze?
We do already know that Nora Fries exists in the Arrow-verse, and the casting description listed her as the "wife of Mr. Freeze." Given that he was explicitly named "Mr. Freeze," we can assume that he's not in his pre-villainous role as plain old Victor Fries. If he was captured by one of the Bats, he would undoubtedly be held in Arkham Asylum, and that would put him under the purview of Dr. Deegan.
After Caitlin and Co. discovered that Thomas Snow had a Killer Frost-esque identity of his own, he ran off, presumably with the information that Barry Allen is The Flash. Thomas (or Thawne as Wells) could have given Victor Fries the truth of The Flash's identity before he became Mr. Freeze. Alternately, Thomas could contact Freeze somehow now that he had his plan foiled by Team Flash with the goal of punishing Barry.
If Thomas tells/has told Mr. Freeze that Barry is The Flash, Freeze could have told Dr. Deegan -- who is said to potentially be even crazier than the inmates under his care -- as well. Given that Oliver's identity as the former Green Arrow is hardly a secret anymore after the end of Season 6, the reveal of Barry's identity would be all Deegan needs to know to make the switcheroo.
Thus, Thomas Snow may have inadvertently revealed how and why Deegan rewrites Barry and Oliver's realities in the "Elseworlds" crossover. We'll have to wait and see. The Arrow-verse crossover begins on Sunday, December 9 at 8 p.m. ET with an episode of The Flash, then continues with Arrow on December 10 and Supergirl on December 11. For more upcoming viewing options, swing by our midseason TV premiere schedule.