X's for Eyes, at its heart, is a pulp adventure. A kind of sci-fi-spy mashup with a slathering of bizarro across the whole thing. I think the author, Laird Barron, describes it nicely:
The narrative itself is beautifully written and the entire story only suffers, if at all, from an avalanche of cheekiness. You'll hardly believe the two brothers, Mac and Dred, are as young as described, considering their proclivities. Or when they're emotionally distraught. When the reader needed to grasp the emotional hook for dramatic tension, it was sometimes hard to tell when the protagonists cared most or felt real loss. Perhaps it's been their lifelong training to inherit the villainous family empire that keeps them cool or the ruthless detachment of their family, in general. As protagonists, their primary attachment seems to be to each other and no one else because no one else can be trusted. Regardless, the entire read is a wild adventure lanced through with bizarre super-science and ruthless operators. I strongly recommend reading this novella in one sitting—something I'll have to do in the future—in order to get a comfortable grasp on the various opposing families and their alliances.