‘The Flash’ Season 2 Spoilers: ‘Arrow’ Star Katie Cassidy Will Crossover In Upcoming Episode; Who Is Black Siren?

Although “The Flash” is taking a break until April 19, that doesn’t mean that the CW and the producers are going to stay silent until the hero’s big bout with Zoom in episode 18. It’s been revealed that Season 2 of the CW series will feature yet another crossover with its sister show “Arrow,” only this one will be more complicated than ever.

Fans of “The Flash” can comprehend a lot of crossover movement between shows. In fact, they recently followed the character to a whole other network to see him team up with Kara Danvers (Melissa Benoist) on “Supergirl.” Before that, they watched John Diggle (David Ramsey) travel to Central City to help The Flash (Grant Gustin) stop King Shark. According to TV Line, the penultimate episode of Season 2 will see “Arrow” Season 4 cast member, Katie Cassidy, make her way to “The Flash,” but not in the way most fans would think.

The outlet reports that Cassidy’s character, Laurel Lance (A.K.A. The Black Canary), will meet the Central City team, but not as herself from Star City. Instead, Laurel’s Earth-2 doppelganger, Black Siren, will encounter the team in another parallel universe adventure. In DC canon, Black Siren originated as a character on the “Justice League” animated series. She was originally conceived as the Golden Age version of The Black Canary, as most of the Earth-2 doppelgangers on “The Flash” have been. However on the animated show, she was actually the mother of Laurel Lance, not the Earth-2 Canary herself.

As ScreenRant notes, it’s unclear at this time if Black Siren will emerge from the parallel universe of Earth-2 as a friend of foe. Throughout Season 2, “The Flash” has been having fun with its characters by taking those that fans thought to be good and showing that their dark sides could have emerged if their timeline had gone slightly different. Notably, in the two-part story “Welcome to Earth-2” and “Escape from Earth-2” the gang had to deal with the villain Killer Frost, who turned out to be none other than the doppelganger of Caitlin Snow (Danielle Panabaker).

Another question for fans of “The Flash” is whether Barry Allen (Gustin) will encounter Black Siren on his homeworld of Earth-1, or if his plan to increase his speed and re-open the breach to Earth-2 works, sending him to meet Black Siren on her own turf. Luckily, the answer to that question will come sooner than Cassidy’s expected May 17 appearance. According to the teaser for episode 18, coming on April 19, it seems Barry uses his newly-discovered tachyon device to track Zoom, who they know to be Hunter Zolomon (Teddy Sears), and re-open the breaches and confront the monstrous baddie once and for all.