WARNING: The following contains spoilers for "Crisis on Infinite Earths, Part 2," which premiered Monday on The CW.

One of the bigger mysteries currently running in the Arrowverse is what happened to Earth-1's Bruce Wayne. When Kate Kane debuted as Batwoman in the crossover event "Elseworlds," we learned that the Dark Knight had mysteriously disappeared a few years prior, leaving Gotham City in a dreadful state. With no one else to defend the city from threats such as Alice and the Wonderland Gang, Kate took it upon herself to become the city's new Caped Crusader.

But fans can't help but wonder what happened to Bruce Wayne. From what we know of the character in the comics, it's not exactly like him to leave everything behind, especially in a state far worse than when he was patrolling the streets. Surely, the Dark Knight must have a good reason for his absence. Some have theorized the character was taken off-world, or to another dimension. But perhaps "Crisis on Infinite Earths, Part 2" just revealed the answer.

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In the crossover's second episode, Kara Danvers and Kate Kane travel to Earth-99 in search of the Monitor's so-called "Paragon of Courage." Their quest leads them to this reality's Bruce Wayne, played by fan-favorite voice actor Kevin Conroy. But this Bruce isn't what Kate and Kara expect: this Batman took a terrible turn towards the darkness and became a murderer. He explains that it was a slippery slope, and that putting down one of his enemies permanently led to another, and another. Now, he has a case filled with mementos of villains he killed, including Joker, Riddler and Mr. Freeze.

What also stood out in the tense interaction, and might correlate directly to Earth-1, is that Conroy's Bruce Wayne explains to Kate that his reality's version of Kate became Batwoman in the wake of his becoming a killer.

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Now, could this be a clue as to what happened on Earth-1? Since Kate took up the mantle of the Bat in Bruce's absence, it seems plausible that the Arrowverse's Batman killed his first victim and that, instead of falling further down that rabbit hole like Conroy's Batman, he chose to walk away from it all, isolating himself following his failure.

Batwoman -- "Pilot" -- Image Number: BWN101d_0412.jpg -- Pictured: Ruby Rose as Kate Kane/Batwoman -- Photo: Kimberley French/The CW -- © 2019 The CW Network, LLC. All Rights Reserved.

This could mean that Earth-1 and 99 share a similar timeline or that events took a different turn at one specific point, as is sometimes the case in alternate realities. If anything, this eye-opening interaction may give Kate a push in looking more closely into Bruce's disappearance on Batwoman.

"Crisis on Infinite Earths" continues on The Flash on Tuesday, Dec. 10, at 8 p.m. ET/PT. After the winter hiatus, the crossover will conclude on Tuesday, Jan. 14 in Arrow at 8 p.m. ET/PT and in DC's Legends of Tomorrow at 9 p.m. ET/PT

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