Last season, The CW’s Arrow killed off longtime series regular Laurel Lance, played by Katie Cassidy. The character had been around since the show’s beginning, and despite a torturous subplot that threatened to drag down the show’s otherwise phenomenal second season, she had recently gotten things back on track by developing her own superhero identity and becoming a valued member of the Green Arrow’s support squad. But then she died, and even though time travel is pretty common in Arrow’s universe, there was no way to bring her back. Luckily, The Flash had previously introduced a character named Black Siren who was Laurel Lance’s evil doppelgänger from Earth-2, and she recently visited Arrow to terrorize our heroes and generally make them feel bad about their Laurel getting killed.