Duo is a mysterious galactic officer, who's sworn duty it is to destroy evil energy. He's an incredibly adaptable, noble and determined hero with a strong sense of justice, who can even sense it from others he partners with like Mega Man. He doesn't seem much for talk, but it's not because he's not competitive, it's because he'd rather let his performance and Hard Granger do all the talking.

I personally envision Duo as having a voice and personality like that of a mature, brotherly soldier, so that should be most important to bring to the audition.