Captain Richard Madden
We'd like to make fun of Captain Richard Madden's "long horseface," but we're too scared (4). The man is ruthless, unstoppable, and in Yu Tsun's words, "implacable" (2). That makes him terrifying.
Yet Captain Madden is not really a bad guy. Sure, he hunts his enemies down like a well-oiled machine, but it's nothing personal. As Yu Tsun points out, he's obliged to be implacable. See, the thing is, he's an Irishman in the service of the English armed forces, at a time when relations between the two nations were particularly frosty. Which means that – like our protagonist – Madden has something to prove to his superiors. Since the English don't really trust the Irish, his nationality means that he's "suspected of equivocal feelings if not of actual treachery." That's why Yu Tsun doesn't blame Madden for making it his personal mission to hunt him down. After all, "how could he fail to welcome and seize upon this extraordinary piece of luck: the discovery, capture and perhaps the deaths of two agents of Imperial Germany?" (2).
No hard feelings, scary dude! But, um... we're going to run like heck now.