Who is Brooks Campbell from Season of the Machete and what is their importance?

Campbell is a government agent, identified at one point as working in the U.S. Embassy and later as a CIA agent. Campbell is supposed to be overseeing the Roses as they work in San Dominica and he believes in his ability. Campbell seems to think that because he is a government agent, Damian Rose is going to acknowledge that Campbell is somehow in control. When Damian doesn't, Campbell is angry. Though he's caught up in the web of intrigue regarding this case, Campbell does seem to be one of the good guys.