Wessel Ebersohn’s seventh rule of thriller writing
You also need a villain. Now the writing schools tell you that this chap is called an antagonist. I presume he or she (usually he) gets that description because he is anti the hero. Seems logical. Now he needs to be bad, the worse he is the better for your book. In due course we will return to different sorts of villains, the believable, the unbelievable, the inexplicable and the understandable. You get them all.