'The Flash' Showrunner Explains Why Tom Cavanagh Is Playing the Reverse-Flash in Season 5

The Flash has brought back a pretty prominent foe in its fifth season, and now we know why he's taken on a particular face.

In a recent interview with TVLine, showrunner Todd Helbing was asked about Eobard Thawne (Matt Letscher) returning in Season 5's future-set sequences -- and particularly, why the character is being portrayed by Tom Cavanagh. As fans will remember, Eobard took on the identity and face of Harrison Wells as a way to blend in while in the past, something that has a unique domino effect to these scenes.

"No, we love Matt — he's fantastic as Reverse-Flash, too." Helbing explained. "But it's funny, if you plot out the Thawne timeline — I think there's a version of this online somewhere — it makes more sense, logically, in a weird, time-travel way, that this is the Thawne that we see. Also, the whole theme of this season is "legacy," so it felt more applicable in the way that we introduce Reverse-Flash, as Wells, for it to play out that way with Tom."

Helbing also addressed the whole nature of Eobard working with Nora West-Allen (Jessica Parker Kennedy) in the future, despite her being the daughter of Thawne's nemesis, Barry Allen (Grant Gustin). Over recent episodes, it's been revealed that Nora didn't know key things about Barry's history as a speedster, including the fact that Eobard was the one who murdered the original Nora Allen.

"In the future, Iris has dampened Nora's speed and kept her powers from her, so I think this all falls in line with 'I don't want my daughter becoming a speedster and possibly being fated the same way her father was. And If I explain to her this whole backstory about how Nora [Allen] was massacred by this Man in Yellow….'" Helbing added. "I mean, Nora ultimately finds her way to Thawne, but in that time period he is in prison, so he is "around." It's just a way for Iris to try to keep Nora away from Thawne and learning all the stuff she doesn't know about."

And according to Helbing, the nature of Nora and Thawne's work in the future could come to a head in an upcoming episode, in which Barry and Iris West-Allen (Candice Patton) visit the Flash museum in the future.

"Nora is working with Thawne, and after her experiences with Barry and Thawne in Episode 8, she certainly knows Barry's reaction to Thawne." Helbing revealed. "Now that she has a full understanding of their history, it makes it a little more complicated for her and Thawne in the future, and how she thinks her parents and everybody else on Team Flash would react to that [partnership]. It gets a little dicey for her, a little tricky, and in that episode (airing Jan. 29), there's a situation that arises where Barry and Iris could learn [the truth], so Nora tries to keep that from happening. It's a [fake science] trip that sort of goes awry."

The Flash airs Tuesdays at 8/7c on The CW.