Nonso Anozie on his role as Sergeant Dap: "I'm just angry all the time."

Online magazine The Root recently spoke with actor Nonso Anozie about working as a black actor, his role in Game of Thrones, and his upcoming appearance as "Sergeant Dap" in Ender's Game:  
TR: Tell me about Ender's Game, the movie you're filming in New Orleans with Viola Davis.

NA: It's starring Hugo's Asa Butterfield -- we worked together on Nanny McPhee Returns -- Harrison Ford, Viola Davis and Ben Kingsley. Ender's Game is set 60 years from now; Earth has been attacked by aliens, and we are preparing a pre-emptive attack on the [next set of] intruders. It's really dark, actually. I'm a hard-ass in this one. In The Grey I was a bit soft and friendly; in Game of Thrones, Xaro is smooth; and in Ender's Game, I'm just angry all the time. I like the variances of characters I get to play.

In the book, Dap functions as a sort of maternal-figure to the new students (Launchies) as they acclimate to Battle School, the only person there who is "paid to be nice to [them]." He explains how to navigate the ship, advises them generally regarding behavior, and essentially tucks them in at night. Later in the novel, he reports to General Pace (Chief of the I.F. military police) and warns him about Bonzo's plot against Ender.

Doesn't really sound like the job of a "hard-ass," does it?

However, look at this quote from Ender's Game author Orson Scott Card from 2010:
We have to cut out a lot. I mean I can tell you that the plan right now is Ender agrees to go to battle school there at home and the next thing we see is he’s walking in the door to Bonzo’s army and everything in between is there to read in the book. But we will cut straight to the chase because we have to get him out of Battle School halfway through this movie or we don’t have time to make the ending work. That’s what we found out draft after draft. (YouTube)
Again, this is a rather old quote, but if the majority of the "Launchie" phase is skipped (which seems likely to be the case), it would make perfect sense that the Sergeant Dap of the movie is going to be different than the Dap of the book.

What do you think he's so angry about? Possibly about the way Ender is being treated by those with authority in Battle School? Or do you think Dap is on Graff's side? Let us know in the comments!