That Protoss word, you know.
erez, I can't seem to find any site with Brood Wars storyline. Anyway, Kerrigan seems to somehow control the Zergs (most of them, anyway). Now that I thought of it, that does seem peculiar. Maybe she just controls an Overmind?
Duran seems to be either a Confederate officer who joined the UED (Earth's) invading fleet, later betraying it for the Zergs, either an ancient being, possibly from the Xel'naga days. Either way, he does seem to make great successes in creating an artificial hybrid species between Protoss and Zerg, and plans to, apparently, conquer the galaxy with it (probably so that Blizzard, if it ever starts work on SC II, will have a new villain).