SPOILER WARNING: This article contains major spoilers for “Crisis on Earth-X, Part 4,” the fourth episode of this year’s Arrowverse crossover.
In the first two parts of “Crisis on Earth-X,” this year’s Arrowverse crossover, Dark Flash revealed that he is actually Earth-1’s Eobard Thawne, despite his death in DC’s Legends of Tomorrow Season 2. As such, he and Barry have a long history, stemming from Thawne murdering Barry’s mother Nora when he was just a child. Now, Thawne is loose on Earth-1 again, free to terrorize Central City and Team Flash as he pleases.
After zipping all over Central City in a climactic battle, Barry over came Thawne and slammed him up against a concrete wall. Barry began to vibrate his hand, in the same way Thawne does when he intends to kill, but Barry hesitated before delivering the fatal blow.
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“Go on! End it!” Thawne hissed. When Barry continued to stall, Thawne yelled, “End it!”
After a moment, Barry stopped vibrating and lowered his hand. “What’s stopping you?” Thawne inquired. “Ah, I forgot! Barry Allen is above killing. Isn’t that right?”
Barry stepped back, freeing Thawne from his grip. “Get out of here,” he ordered.
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Thawne stalked away, only to turn slightly and look back at Barry. “I wonder what face I’ll be wearing next time we meet, Flash,” he said with a sinister smile.
“Can’t wait,” Barry spat, and Thawne took off, away from Barry and the fight.
It’s unclear why Barry let Thawne go, as he did not have a chance to explain his reasoning. However, in doing so, he has chosen to let the threat of Reverse Flash remain on Earth-1. Seeing as Thawne will stick around, he will likely turn up again sometime, in this season or otherwise.
This year’s four-part crossover “Crisis on Earth-X” will air across two nights, beginning Monday, Nov. 27 with Supergirl and Arrow (on a special night for one week only) and concluding Tuesday, Nov. 28 with The Flash and Legends of Tomorrow.