Tom Cavanagh on 'thrill' of returning to The Flash, reviving Reverse-Flash in ‘Armageddon’ event

After Season 7 of The Flash, fans of the Arrowverse show thought they may have seen the last of Eobard Thawne/Reverse-Flash, along with Harrison Wells (both played by Tom Cavanagh). Not so! In last week's installment of the big Armageddon crossover event on The CW, Barry Allen (Grant Gustin) traveled to a future where Thawne is seemingly married to his wife, Iris West (Candice Patton), and occupies the role of Central City's Scarlet Speedster. As if that wasn't bad enough, Barry finds himself in the Reverse-Flash suit!?

"I think the larger point, which doesn't give things away, is when you've put in the amount of time that you put in when you're telling a Batman-Joker story or Lex Luthor-Superman story or Flash-Reverse Flash story, you've earned, in many ways, the big face-offs and twists that renew the rivalry," Cavanagh said during a chat with Entertainment Weekly. "This is an instance when I felt like the writers' room did a tremendous job of organically working up to the clash of these two people."

Of course, the actor couldn't go into great detail about what's motivating Thawne in this timeline. Is he really a good guy now? Does he truly care for Iris? Or is this some sort of ruse? Has the erstwhile villain conceited some twisted scheme to drive a proverbial knife into Barry's back? Your guesses are as good as ours.

"If you layer it on as just one thing, you might be missing some opportunity there," Cavanagh continued. "What's nice is you know that Eobard Thawne, as written [on the show] and in the 80-plus years [of comics] canon, is somebody who doesn't really leave things to chance. As an actor who likes to explore as many different colors and layers I can put in there, I think the idea that those two people come together on screen finally for the first time in forever, that's a very large moment in the show, and one that was a delight to play."

Cavanagh also addressed the sheer awesomeness of the reveal and how it proves that you can still wring surprises out of a long-running TV series like The Flash. "For both of us, when you get into season 40 of a television show, sometimes the cool-factor moments can be a little elusive, and this was definitely a thrill," he said.

The fallout of Thawne assuming Barry's identity will be explored further in Part 4, which airs tonight at 8 p.m. EST.