Posted by Michael Patterson @WatchTower
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Michael Patterson

With Arrow about to begin its fifth season, the highly anticipated 100th episode won't be far behind. With such a momentous occasion looming, it shouldn't come as a surprise to hear that Arrow veteran Katie Cassidy will be returning for the episode. With her already set to appear in a flashback in the Season 5 premiere, Cassidy took to Facebook to post this photo, causing fans to speculate — and hope — that she would be back for the show's 100th episode.

Furthermore, showrunner Marc Guggenheim would then take to Twitter, confirming that she would indeed be returning to the show for the 100th episode. But the question is: In what capacity?

Black Canary Or Black Siren?

Cassidy portrayed Laurel Lance/Black Canary for the first four seasons until she was controversially killed off last season, which caused outcry among the fans. She would later appear on The Flash as Laurel's villainous Earth-2 doppelganger Black Siren, and received great reviews for her seductive yet empowering performance — her cunning facial expressions and sultry walk helped to make her the perfect villain.

The fans were still understandably unhappy with Laurel's death on Arrow, and it seems their voices were finally heard as it was revealed at Comic-Con that Cassidy had signed a new series regular contract across all CW superhero shows including Arrow, The Flash, Legends Of Tomorrow and presumably even Supergirl.

Hero to Villain: Cassidy as Black Canary on "Arrow" and Black Siren on "The Flash."
Hero to Villain: Cassidy as Black Canary on "Arrow" and Black Siren on "The Flash."

Of course, we don't actually know yet which iteration of Laurel will appear on the 100th episode. You might think that she could appear in another flashback, or that the effects of Flashpoint over on The Flash will have undone her death, but Marc Guggenheim already debunked both those theories in regards to Jamey Sheridan's return as Robert Queen, so why would that be any different for Cassidy? Furthermore, he has previously insisted that the Laurel Lance of Earth-1 was dead. So that only leaves one option: Black Siren.

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Is Black Siren The Villain Of The Crossover?

Black Siren on "The Flash" (via The CW).
Black Siren on "The Flash" (via The CW).

Arrow's 100th episode is already a major cause for excitement. And if that wasn't enough, it was recently revealed that the episode would also serve as Arrow's offering in the CW's upcoming major four-way, three-night crossover, featuring characters from Arrow, The Flash, Supergirl and Legends Of Tomorrow. We also recently discovered that one major threat will bring all of the shows together. Could that threat be the Black Siren? When you think about it, she is connected to at least three of the four shows.

  • The Flash: Cassidy appeared as Black Siren last season and kicked some major ass as one of the leaders of the "metapocalypse." Upon her eventual defeat, she was imprisoned in the S.T.A.R. Labs metahuman prison. Despite being from Earth-2, she was imprisoned on Earth-1 while all of the other Earth-2 metas were sent back to where they came from. This very well could have been due to Cassidy's popularity and, moreover, to being the character back for future episodes.
  • Arrow: It's the show's 100th episode so of course Cassidy should appear on it. And Black Siren's arrival in Star City would definitely be a perfect storyline for this major episode. During the character's debut on The Flash, Barry and the team decided not to tell Laurel's Arrow family about her doppelganger. Certainly a destructive Black Siren would make for some compelling scenes with Laurel's dad Quentin and sister Sara.
Sisters: Laurel and Sara Lance on "Arrow" Season 2.
Sisters: Laurel and Sara Lance on "Arrow" Season 2.
  • Legends Of Tomorrow: Laurel's death affected the entire Arrow-verse, and no one was more upset by it than her sister the White Canary Sara Lance. If Sara were to discover that her sister's doppelganger was in town, it would definitely lead to some incredible scenes between the two. Katie Cassidy and Caity Lotz always delivered in emotional scenes involving the two and I have no doubt that they would do it again here. Furthermore, imagine seeing the skilled metahuman take on the former assassin — a goosebumps inducing thought. On an interesting note, Season 2 of Legends will see Sara coming face to face with an alternate version of Laurel's killer Damian Darhk. If she were to kill him in the past, would that stop Laurel's death from ever transpiring?
  • Supergirl: Despite Supergirl taking place on another Earth, the character will be featured on the other three shows during the crossover. The show's leading lady Melissa Benoist previously stated that she would love to team up with Black Canary. But if that doesn't happen, she could always end up facing Black Siren. That would be equally as awesome, right?
Black Siren imprisoned on "The Flash."
Black Siren imprisoned on "The Flash."

With the most ties to each show, Black Siren would be an ideal villain for the highly-anticipated crossover and would definitely explain Katie Cassidy's as of yet unknown role. Thanks to Laurel's loved ones spreading out across most of the shows, there is legitimate reason for the evil doppelganger to appear on almost all of them.

A Welcome Return

With Katie Cassidy returning for Arrow's 100th episode, there are certainly going to be many people wondering how it's possible, given that her character was killed off. But with the shared universe full of resurrections, alternate earths, time travel and metahumans, anything is possible. Furthermore, with Earth-2 doppelganger Black Siren being very much alive and well, there's a strong possibility that she could be featured on Arrow's landmark episode and be the major threat on the Arrow-verse crossover.

Whatever happens and whichever version of Laurel shows up on the show, I can easily say that I am thrilled to hear of Cassidy's impending return. She was an integral part of Arrow since its beginning and without a doubt, deserves to be featured heavily in the 100th episode.

Welcome Back Katie!
Welcome Back Katie!

Arrow Season 5 premieres on The CW on October 5. Are you excited to see Katie Cassidy return for the 100th episode? Let us know in the comments!

[Source: TVLine, Katie Cassidy's Official Facebook]