"This is what makes you such a good reporter," Malone's mystery character tells Lois Lane (Amy Adams), "Stuff like this still shocks you."
And that's it. With a smile, a shake of the head, and those two lines, Jena Malone comes and goes in the new trailer. So just who is she? Previous speculation and rumors have included both Carrie Kelley, the Robin of the classic Batman story The Dark Knight Returns (which was pulled from significantly for this film, especially when it came to character design) and Barbara Gordon, the daughter of Gotham City police commissioner James Gordon and civilian ID of the vigilante Batgirl and eventually Oracle. Of course, both of those characters are traditionally redheaded in the pages of DC Comics, a hair color Malone has sported, prompting much of that speculation. Now, we see that she's rocking bright blond hair in this movie, which seems to throw those out the window.
Of course, with Lois in this universe rocking a reddish-brown, it's possible they just wanted to differentiate Malone's character. More drastic things have happened in the translation from comics to screen, after all. And while Zack Snyder previously went on-the-record saying she's not "Robin or Batgirl," he's never commented on whether she could still be Barbara or even Oracle. This close interaction with Lois Lane certainly throws another wrench into things, though.
We'll find out for sure who Jena Malone plays in Batman v Superman and perhaps could play in future films in the DC Cinematic Universe when the Ultimate Edition hits Digital HD on June 28, 2016 and hits the various Blu-ray editions on July 19, 2016.