Character Analysis
Cesar is one of the young terrorists. He could also be the next Justin Timberlake of opera. Just instead of getting started in a boy band, it's with a group of terrorists.
So where does his stellar set of pipes come in? One day Roxane doesn't start singing at her usual time, so he bursts into song and amazes everyone. Like a stereotypical opera singer, he's a little high-strung, so when Roxane tells him to stop (because she's worried he'll hurt his voice, not because she thinks his singing is bad), he misunderstands her and spends a while sulking in a tree. Eventually they get it sorted out, though, and he starts lessons (9.2-132). Roxane is convinced that he could be opera's next big thing. It's like what everyone hopes to find when they're judging The Voice, but for opera.
Cesar is one of the many characters who helps us see that the terrorists are people, and people who may have more in common with the hostages than might first appear. He's also the only character in the novel who has a talent similar to Roxane's. It's not trained yet, but it's of a similar caliber and, with practice, could be refined to be like hers. That's another reminder of the terrorists' untapped potential in general.
Like Carmen, and for similar reasons (see her character analysis), Cesar is headed for a tragic end in this novel. The fact that he's got a great voice doesn't make his death more tragic than any of the other teenagers among the terrorists, but it does emphasize what the outside world is losing with his death.
Who knows how many talents they had that might have been discovered if their life circumstances had been better and they hadn't become terrorists? No one ever will. And that's the tragedy.