Making is to 100 episode of TV in the modern landscape is no easy feat. So many shows last only a season or two before meeting an untimely end. That's what makes The Flash's achievement so special and worthy of celebration. What you might not have expected, though, was an episode that also served as a game changer for not just this season, but the series as a whole. Warning: The following contains spoilers for The Flash's 100th episode, "What's Past is Prologue."

While visiting the past was a nice way to honor all that the show has become, what was especially important is how it shaped the future--namely how it involves Nora (Jessica Parker Kennedy). "I really didn't think I'd have a big part of it because I always sort of felt like the 100th episode should represent everyone that had been in the show so I was so surprised when I knew I was going to be such a huge part of it," Kennedy told GameSpot on The Flash 100th episode red carpet.

She did play a massive role, though, which involves her own future. After meeting the Eobard Thawne (Tom Cavanagh) that tormented her father throughout Season 1 of the series, it was revealed she's actually working with him--or some version of him--in the future, long after her father disappeared. What her goal is, though, has yet to be revealed.

"There's something going on but we don't understand it exactly what it is," she said. "Obviously, as the season goes on, that will make sense but I think the biggest thing is, is Norah good when there's a part of Norah that's bad? What are the reasons she's there?"

That's the question on the minds of every fan after realizing Barry Allen's (Grant Gustin) daughter is working with his most dreaded enemy in some way. What would bring her to it and what happens now that she sees the man he truly was?

Of course, looking at it from Cavanagh's point of view, bringing back Thawne is an exciting challenge. How do you revisit a former character but keep it fresh and new?

"I always think if you're fortunate enough to be on a long-running TV show, maybe you don't necessarily have to reinvent but it's best not to get too staged in, you know, what you present to the viewership because I think they know you know an occasional ignition in one way or another," he explained. "I think that with taking the classic villain, keeping him the classic villain, but showing a different error or different side or different aspect, if you will, with it was enjoyable."

That was also the route showrunner Todd Helbing and his writers wanted to take when it came to penning the script for the episode and deciding where it would lead as the season goes on. "We don't wanna just do the same villain over and over and if we had the exact same attitude with Eobard Thawne, that we've seen this whole time, that's not going to be interesting either," he said. "So, he was part of the pitch from the beginning and I think what we really wanted to do was just see a different attitude from Thawne that we hadn't, see him in a different light and, you know, there's a big theme of legacy this season. And so, when we started talking about that with every other character and then we got to Thawne, it's like, 'What does legacy mean to him?' So that's what we start to touch on in the background."

What does this mean for Sherloque, though? The version of Wells helping the team out in current day was certainly teased to show a connection to Eobard. In the 100th episode, they both refer to Nora as a "clever girl," referencing Jurassic Park. However, as Helbing revealed, the two are not the same person.

"I'll just say he's has a different agenda than Thawne." the showrunner teased. As for what that agenda is, and whether it's good or evil, you're going to have to wait for the season to play out. We'll also have to wait to see whether Barry and Nora traveling back in time will have any impact on the timeline. "I feel like towards the end of the season is where we're going to see what kind of repercussions episode 100 had," Gustin said. Helbing, meanwhile, teased, "There's something that will happen probably way down the line that you realize but, no, right now we're not playing it in the same way like that we do."

With such a massive episode that featured so many major moments, you're going to have to wait for any kind of immediate follow-up. Next, The Flash--along with Arrow and Supergirl--head into the massive "Elseworlds" crossover. The event kicks off on December 9. Make sure to check out our "Elseworlds" photos and spoiler teases so you're ready to take it all in.

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