TV Guide brings us the following:
The fact that Lotz's character, whose name Kreisberg declined to reveal, has a connection to the Black Canary has worried fans who believed that Katie Cassidy's Laurel Lance would fill that role, as the comics dictate. But Kreisberg wants to set the record straight. "The character that Caity is portraying is the beginning of the Black Canary story and we're really excited for the fans to go on the journey with us," he says. "So much of our show is about defying expectations, meeting expectations and exceeding expectations, and we really want our fans to experience the show by watching it and enjoying it and enjoying all the twists and turns and surprises the way we intend."
Kreisberg likens the Black Canary's journey to other characters that the show has already introduced with a twist. "Everything about our show is about origins and evolution," he says. "When we met Deathstroke, everyone automatically assumed it was Slade Wilson [Manu Bennett] in the mask, but then we revealed we met Slade Wilson later. With Tommy [Colin Donnell], we thought that that was Merlyn, but Tommy was really the beginning of the Merlyn story because we saw how it evolved to John Barrowman and beyond. Oliver [Stephen Amell] himself, when we first meet him, he's not the Green Arrow yet. The series itself is an evolution of this character."
As for what this means for Laurel, Kreisberg says, "Everyone knows that Laurel Lance is the Black Canary. That's the way it is in the comic books, but how we get from A to B is the story of our show. In the same way that Oliver, when we meet him, is the vigilante, but this season he's going to becoming the Arrow, that's the step of his journey to eventually becoming the Green Arrow. Laurel Lance right now is a lawyer with a lot of heart and a lot of humanity and courage. But it takes more than that to put on the mask and go out and fight crime. Our series is the evolution of that. People will see how Caity Lotz fits into Laurel's journey along the way. For us, it's very emotional and surprising and exciting. I would say to everybody, we haven't let you down so far. Keep going on this ride with us."