A Black Canary who's not Laurel, and now a villainous daughter of Ra's al Ghul who's not Talia. Arrow is really subverting expectations all over the place in season 2.
The latest news, via TV Guide, is that Spartacus actress Katrina Law is joining the show as Nyssa al Ghu, Ra's' love child with a Russian woman, and just a bit lesser known than her half-sister. On the show, she'll be a powerful member of the League of Assassins, sent to Starling City to bring the Canary (Caity Lotz as Sara Lance, Laurel's sister) back into the fold. Basically, she'll be Talia, but not. Nyssa makes her first appearance in the 13th episode of the season, appropriately titled Heir to the Demon.
TV Guide wonders if this raises the possibility that Summer Glau's Isabel Rochev is actually Talia in disguise, but I think that's unlikely. Rather, I think this raises more questions with no easy answers about the convoluted juggling of rights and characters caught between the TV and film sides of the DC universe.
Marion Cotillard played Talia in The Dark Knight Rises, so was it perhaps deemed too confusing to have a different version of her show up on TV so soon afterwards? But that would throw a wrench into Steven R. McQueen's dreams of playing Nightwing on the show, wouldn't it, since Nightwing is almost certainly going to show up in Batman vs. Superman. Ahhh, I give up on trying to figure it all out.