What Did Nora Do On 'The Flash'? The Mystery Girl Apparently Made A "Big Mistake"

Shane Harvey/The CW

Spoilers for The Flash season finale. Listen up, Team Flash, we finally know the identity of the mystery girl on The Flash, so fans can now stop calling her "mystery girl" and "the waitress from Barry and Iris' wedding." Who is she? The mystery girl in The Flash is Nora West-Allen, Barry and Iris' future daughter. But that's not the only big revelation to come in the season finale, "We Are The Flash." Nora reveals herself to Barry after committing what she describes as "a big, big mistake." But what did Nora do on The Flash? And can Barry really do anything to fix it?

When Nora crashes Jenna Marie West's (that's Joe and Cecile's newborn daughter) homecoming, it's not an especially happy occasion. Overwhelmed, and clearly freaking out, she walks into the West house frazzled. "Hi, we need to talk," she says. After Caitlin, Cisco, Wally, and a newly revived Dibny recognize her as the girl from Jitters and the wedding, Barry notices that she's wearing the same jacket Iris wore when she temporarily had Barry's powers earlier this season. He asks where she got it, and she says she got it from Iris and kept it after she let her "borrow" it. Everyone is pretty confused until she introduces herself as Nora, Barry and Iris' daughter from the future. "I'm your daughter, Nora, from the future. And I think I made a big, big mistake," she says.

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It's unclear what exactly Nora did that was so horrible. But considering the fact that prior to this scene, she had shown herself to every member of Team Flash except for Iris, it's safe to say that it's pretty big. Why else would she expose herself to the very person she was avoiding? Knowing everything we do about her (which is not much), it's safe to say that whatever mistake Nora made on The Flash, it has something to do with the Speed Force and time travel.

Nora has been hovering around Central City since Barry and Iris' wedding, and while she's mainly kept a distance from the action, specifically not jumping in to help fight the Earth-X Nazis or to join the fight against DeVoe, in "We Are The Flash," all of that changes. After successfully leading Dibny to reclaim possession of his own body (the one that DeVoe had co-opted), Barry thinks he's defeated the Thinker, but he's wrong. The Thinker had a failsafe in case his plan didn't work out, and the S.T.A.R. Labs satellite is sent hurtling toward Central City, threatening to destroy everyone there. As Barry runs to deliver an atomizing blow to the satellite to keep the projectile from hitting Central City, something happens. Just as he is about to hit it, time stops, and then rewinds. When things are set in motion once more, Barry is no longer the only speedster hurtling toward the satellite. Nora's purple lightning is there, too, and she punches the object at the same time as Barry, lessening the blow to the Flash and, apparently, saving him from being destroyed by the blast.

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Iris makes it clear in the final scene of the episode that she is not pregnant, which means that Nora's actions could have just been a form of self-preservation. She can't exist unless Barry survives the Thinker's attacks. Still, her interference could be the "mistake" she's talking about. However, there could be more to the story. In previous episodes, Nora was seen writing in the symbols of the Speed Force, the same ones that Harry was writing in as he started losing his intelligence, that Barry had been consumed by after exiting the Speed Force. Nora seems to understand the symbols, meaning that she might have a greater knowledge of the Speed Force, and may have manipulated it in ways that Barry himself hasn't even imagined. Barry is all too familiar with the consequences of changing the past (remember Flashpoint?), but Nora's panic is nothing like what Barry felt when he realized his mistake. It's something worse.

The Flash producer Todd Helbing implied that Nora needs help fixing time travel, telling ComicBook.com, "She makes this sort of big mistake at the end of the episode — you see the concern of what she's done, and Barry certainly learned his lessons from time travel, so it's going to be interesting to put him on the different side of the problem and she how he can help her fix it." But, based on her knowledge of the Speed Force and her reluctance to meet Iris, I think there's something bigger at play here. A mistake even bigger than Flashpoint, and one not easily fixed at all.