SPOILER WARNING: This article contains major spoilers for "What's Past is Prologue," the 100th episode of The Flash.


Reverse-Flash just invaded Barry Allen's life in a brand new way. "What's Past is Prologue," the 100th episode of The Flash, revealed Nora West-Allen didn't decide to go to the past on her own. She has been working with Eobard Thawne all along.

The milestone episode saw Barry and Nora travel to the past in order to pick up a few rare items they needed to create a magnet strong enough to negate Cicada's power-dampening dagger. Along the way, they bumped into Thawne at a time before his Season 1 defeat. Nora was incredibly intrigued -- and a little too trusting -- of Thawne. Though Barry was hesitant to answer Thawne's searching questions, Nora supplied them readily, much to Barry's dismay.

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When they got a moment alone, Barry asked if she knew what Thawne had done. Nora regurgitated some of the information she learned from the Flash Museum, not really grasping the magnitude of Thawne's impact on Barry's life. This forced Barry to reveal how Thawne had killed his mother in an effort to make him so broken that he never became the Flash. Nora was absolutely floored by this revelation and, while her hurt seemed to be on her dad's behalf, there was much more to the story.

At the end of the episode, Nora scanned her latest journal entry with Gideon's help. She began to leave a message for someone on the other end, but stopped and decided to deliver it herself. With that, she headed back to the year 2049 and paid a visit to Iron Heights. When she stopped, she stood outside a cell where a man read her journal entry with his back to her. He turned, revealing an older version of Eobard Thawne, still stuck with Harrison Wells' face.

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"We have to talk," Nora spat. Locking eyes with her, he replied, "Yes, Nora. Yes, we do."

The last time we saw Reverse-Flash, he had teamed up with Dark Archer and Overlord for the events of "Crisis on Earth-X." In the crossover's climactic battle, Barry finally got the upper-hand on Thawne, but made the surprising decision to let him go. Thawne sped off with an ominous warning: "I wonder what face I'll be wearing next time we meet, Flash." That is the last time he was seen in the Arrowverse -- until now.

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Of course, we've yet to see how he ends up in prison in 2049 or where he disappeared to after "Crisis on Earth-X." Seeing as the character has returned to the fold, the show will likely present some of these answers in the coming episodes, after this year's crossover "Elseworlds." He'll certainly have to explain himself to Nora; after all, executive producer Todd Helbing told Entertainment Weekly that Thawne has been acting as "her coach."

Additionally, this means Reverse-Flash may be somewhere in Team Flash's present. This would certainly make good on his promise to return with a different "face." Of all the team members right now, Sherloque is perhaps the most suspect; he seems to have a lot of awareness about Nora's duplicity and has taken a suspicious interest in her journal. His actions and even his mannerisms -- particularly his little bow to Nora at the end of the episode -- suggest he isn't being entirely forthcoming with the rest of the team.

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"Here's what I have to say about that. Jessica Parker Kennedy was so winning and, in this day and age, clearly, women are the superior sex. So what is she thinking? I mean, any man in general is like, you really got to vet at this point. We're at the point -- let's really look at -- and then, that guy?! In prison, no less!" Reverse-Flash actor Tom Cavanagh told CBR. "I'm going to seek that guy out! You know what that is? Good television. Because now you're going to tune in to see what 5.09 is, because what is she thinking?!"

Airing Tuesdays at 8 p.m. ET/PT on The CW, The Flash stars Grant Gustin, Candice Patton, Carlos Valdes, Danielle Panabaker, Tom Cavanaugh, Jesse L. Martin, Danielle Nicolet, Hartley Sawyer, and Jessica Parker Kennedy.