Anyone who has ever delved into fictional work or spent half their day browsing T.V. Tropes knows that a good story usually has a good villain -- or, even better, a villain seeking redemption. Looks like Ender's Game screenplay writer and director Gavin Hood felt that such a person was missing from Ender's story as we may have spotted a very interesting character in a scene from the brand new teaser trailer:
We have it on pretty good authority that this is Conor Carroll as Bernard -- right smack in what appears to be the final simulation at Command School -- in a seat which, in the book, would have only been occupied by one of Ender's closest and best.
If this is Bernard, his story arc in the film is vastly different from that of the broken-arm bully who essentially disappears from the novel after the first few chapters. And Bernard having a larger role than we expect is already certain since we know he finds his way into Dragon Army. Conor himself was also well-promoted at Comic-Con and isn't too far down on the IMDB cast list.
So, it definitely looks like good old Bernard does something not only to redeem himself in his commander's eyes but also to become someone Ender trusts and respects.