Spoilers (and plenty of speculation) ahead for tonight's episode of The Flash, titled "Once and Future Flash."
In tonight's episode of The Flash, a trip to the future taught Barry that one of the reasons Savitar was able to do so much damage to Team Flash, and to kill Iris: he had help from Killer Frost, the "evil" version of Caitlin Snow, who had been wooed over to his side with a promise of stability...even if it came at the cost her humanity.
In the closing moments, then, just before the teaser trailer that promised Savitar's true identity would be revealed next week, he revealed himself to Killer Frost -- and what happened next immediately raised our suspicions that Savitar might actually be the returned form of Ronnie Raymond, Caitlin Snow's husband, who died at the end of The Flash season 1.
Ronnie was one half of Firestorm, a hero who fought alongside The Flash to close the singularity that nearly consumed Central City after the first time Barry time-traveled. When Firestorm exploded near the singularity, he managed to close the black hole, but when Firestorm split, Barry only managed to find and save one of the two men who composed Firestorm's matrix: Professor Martin Stein. Ronnie was lost, just hours after his marriage to Caitlin.
So what has us thinking that the mystery baddie is actually Robbie Amell's character? Well...
At the end of tonight’s episode, viewers of The Flash saw Caitlin Snow (Danielle Panabaker) — who happened to be in full-on Killer Frost mode — wandering through a forest somewhere outside of the Central City. In typical Frost fashion, she happened to be walking barefoot through inches of snow, but why would she do that? To meet with the God of Speed himself, of course.
When Caitlin finally found Savitar in the forest, the latter revealed that in exchange for help, he’d be sure that Killer Frost’s alter-ego Caitlin Snow never re-emerges. When Killer Frost asks Savitar why she should trust him, Savitar knelt down and began to take off his suit.
As the man inside the suit emerged, a sense of seriousness came across Killer Frost’s face and she utters a simple line, “What do you need me to do?”
That look of surprise and her immediate leap to loyalty seems like the kind of thing that would be nearly impossible to inspire, especially in Killer Frost who, unlike Caitlin, hasn't yet been demonstrated to form personal bonds.
THICK AS THIEVES
...on Earth-2, where Deathstorm and Killer Frost were lifelong partners.
Even while working for Zoom, a godlike villain who held Earth-2 under his thumb, Killer Frost was willing to throw all of that away and throw in with The Flash because she was so heartbroken and directionless.
Since the very beginning, Ronnie has been Caitlin's North Star, on this Earth or any other, so certainly finding him alive would be something that might cause her some character regression.
THE BLUE ENERGY
A lot of fan theories have centered on the idea of the blue energy in Savitar's armor being indicative of the blue lightning the dark, "five years later" version of Barry Allen trailed during a recent story arc in which an evil version of The Flash from the future traveled back and did battle with Barry and a then-new-to-speedstering Wally.
But now we've got something the kind of makes sense, courtesy a season 2 episode of The Flash.
Y'know: the one where they introduced Jax, the guy who bonded with Professor Stein to form Firestorm after Ronnie's death at the end of season 1. That's when everyone initially speculated we might see Deathstorm, since Professor Stein was spontaneously erupting with blue flame because his physical form was unstable due to being separated from Ronnie.
In the comics, of course, Deathstorm originated as a Black Lantern during the Blackest Night event, and back then the undead Firestorm threw off blue flame. Later, during Forever Evil, another version of Deathstorm would be introduced which was simply an alternate-Earth version of the character, and that character had a gruesome visage but his powers exhibited much like Firestorm's.
When Stein was separated from Ronnie following his death, The Flash saw him get powers that looked like Deathstorm I, for lack of a better term, while the Earth-2 Ronnie, who went by Deathstorm, actually was just an alternate Ronnie, like Deathstorm II.
...but if "our" Ronnie, one separated from Stein, came back and somehow found a way to contain himself in the Savitar armor? What would that look like? Hmm...!
NO TIME FOR LOVE, DOCTOR SNOW!
Earlier this season, before Caitlin's relationship with Julian started to really get complicated, ComicBook.com spoke with Danielle Panabaker about her character's singledom.
"I'm excited for her to not be with someone this year," Panabaker said, adding, "It's not realistic but I'd love Robbie playing Ronnie to come back. That's my dream: they're fire and ice; they're meant to be together."
If Ronnie is Savitar, though, then introducing a former minion of Savitar to inadvertently steal Caitlin's heart and ultimately help her find her way back to humanity would be a particularly ironic way to develop her story -- and it would give the romance that Panabaker suggested maybe her character doesn't need a reason to have existed.
A CRAZY THEORY
...What if that’s why Caitlin seemingly isn’t at the funeral that set spies caught being shot for the finale? What if her redemption is that she pretends to be Iris, essentially forcing Savitar to kill her?