Instead, the Arrowverse has taken advantage of the multiverse introduced in The Flash to bring the actress back as Laurel’s evil doppelganger from Earth-2: Black Siren.
Katie Cassidy has shed some light on the backstory for Black Siren on Arrow.
So far, Black Siren’s history has been mentioned only in passing, with the revelation that on Earth-2, it was Robert Queen who survived the accident, not Oliver.
Emily Bett Rickards: So, Black Siren, when she comes over from the other universe, she still has Lance as a father and Sara as a sister?