Welcome back to The Hollywood Reporter's weekly DC TV Watch, a rundown of all things DC Comics on the small screen. Every Saturday, we round up the major twists, epic fights, new mysteries and anything else that goes down on The CW's Arrow, The Flash, Legends of Tomorrow, Supergirl and Black Lightning, and Fox's Gotham. The new seasons of all the Arrow-verse series are (finally!) almost here, so this week let's take a deep dive into what awaits in The Flash season five ...

Key changes: The Flash has always followed the classic 23-episode season of television, but executive producer Todd Helbing reveals that some big changes are coming to the structure of the series this year. The writers and producers "learned a lot from having a non-speedster with DeVoe [Neil Sandilands] last season," and one of the biggest lessons was that a season didn't have to follow only one major arc.

"One of the pitfalls that we ran into is that it's hard in 23 episodes to have one storyline play out so this year, while there is certainly a spine, we have two or three major stories that go on in different increments — like a first act, second act, third act," Helbing tells The Hollywood Reporter. "That's been helpful in a lot of ways. We learned a lot when Barry [Grant Gustin] was in prison — it was only three episodes, but it really opened our eyes."

Larger theme: There's a lot going on in the new season of The Flash with a new villain in Cicada (Chris Klein); new series regular with Nora (Jessica Parker Kennedy), aka Barry and Iris' (Candice Patton) adult daughter from the future; and the resurgence of time-travel stories, among other things. But the overall theme of season five is shifting focus to the idea of legacy.

"What Barry is wrestling with is: What is he leaving behind?" Helbing says. "It's what every parent eventually gets to when they have kids: 'Am I leaving this world better for them?' For Barry, it's, 'What's more important, being the Flash or a good father?' With Iris, it's, 'What do I really want to do, be the team leader in STAR Labs or get back to my roots and be a journalist?' For Cisco [Carlos Valdes] and Caitlin [Danielle Panabaker], it goes back to the original sin of season one when the particle accelerator exploded and created all these new metas: 'What are we doing to curb this problem?'"

New villain: As The Flash continues its trend of non-speedster villains, DC Comics character Cicada will debut as early as the season five premiere and will wreak havoc throughout the whole season in a way that explores a new perspective of the series. Described as a "grizzled, blue-collar everyman whose family has been torn apart by metahumans," Cicada will target metahumans in his quest to exterminate what he sees as an "epidemic."

"Every year we try to humanize the villain, and this year we're doing it in a way we haven't done before," Helbing reveals. "With Cicada, you see a guy who has been affected by what has been going on for the last four seasons and in a way that's unusual for our show. How he deals with it and what he decides to do is fresh and new. [Last season's big bad, The Thinker] ultimately became the most powerful metahuman ever, so at the end of the season it sprung this new idea of how we could create another villain that wasn't a speedster that could affect everybody. It's hard to create these new obstacles for our team as they are getting more and more powerful and with the amount of superheroes they have on [Team Flash]."

New main character: Fans already know and love Barry and Iris' future daughter Nora, aka speedster XS who has traveled back in time 30 years to meet young versions of her parents, after her few but memorable appearances last season. Apparently now stuck in the past, she outed herself to Team Flash in the season four finale because she needs their help rectifying a "huge mistake" she made. Expect to see a lot of her this season as Helbing reveals that she's in every episode and will have a hand in most of the major stories being told.

"The injection of Nora and her not only enthusiasm, but she's pretty green when it comes to being on the team and having powers, it's fun to see Barry and the team in a new light through her eyes," Helbing says. "She gets to experience what the audience got to experience the first couple seasons, and it's a season-long arc. There are a lot of things going on with her — her relationship with Iris is not as great as her relationship with Barry, it's a little more contentious. We dive into that. And then her relationship with her father and the Flash and why it's so easy for them to get along, and it's not just because they're both speedsters. And her story is also tied in to Cicada and there is a specific reason why she came back at the time that she did. She has three big stories going on."

The 100th episode: As The Flash reaches a milestone of 100 episodes halfway through this season, Helbing reveals the first details about the big celebratory hour.

"We wanted to do something special," he says. "The writers and I had conversations with Greg [Berlanti] and we wanted to take the audience on a trip to remind everybody of all the cool stuff we've done for five years now. We wanted to relive the coolest moments on our show, so we came up this conceit and it both honors what we've done so far and also propels the show for the rest of the season. And Tom Cavanagh directed it, so that felt appropriate since he's been such a big part of this show and played a zillion characters."

The future: Over the course of four seasons, The Flash has flip flopped between light-hearted comedy and extremely dark drama, to both success and failure. The tone of season five sits somewhere in the middle, and according to Helbing that's what the producers believe is right for the series and want to achieve for the rest of the show's run.

"We want to keep telling fun stories and the occasional one-offs we get to do with time travel or last year's 'Enter Flashtime,'" Helbing says. "But at the core, it's this family story, and that's why we've been so successful — it's the love all the characters have for each other. Everybody remembers season one fondly; I love that season just like everybody else, and every season after that got darker and darker. Season three was as dark as we got and we overcompensated with season four with the humor. This season in particular we just got back to the heart and that's really where the show lives. That's the best version of the show. It's OK for some episodes to be darker and some to be lighter but as a whole, that sweet spot is really having equal parts of heart, humor and spectacle."

Fun fact: Season five may only be just beginning, but it's the second half of the season that has Helbing psyched. Fans should gear up for some game-changing, long-awaited moments for the series. Helbing laughs then adds, "The way that Nora factors into it and where it goes is going to be really interesting, and we can't wait until you get right in the [episode] seven, eight, nine part of the season."

The Flash season five premieres Tuesday, Oct. 9, on The CW.