Originally Posted by BatLobsterRises
It's not just her identity that gets revealed in the "twist" though. It's the fact that she was the child in the pit, it's what we learn about Bane from it. What we learn about what Bruce, Bane, Talia and Ra's have in common and how they contrast with one another. It's about the thematic clarity it offers.
A twist IMO, is something that's meant to turn the entire story on its head. The Talia reveal doesn't turn the story on its head, it actually brings it into greater focus and offers illumination and thematic resonance.
Great point. IMO, the biggest reason why her character was meant to be a secret going into the film was to preserve the structure of the story more than anything and to keep viewers invested in the backstory of that child and the Pit.