Derek Stillwater is an agent with Homeland Security.
A Special Forces veteran of the first Gulf War, Stillwater is one of the leading experts on germ warfare with a doctorate in biological and chemical weapons. He is also a top operative for the newly formed Department of Homeland Security.
Being as smart as he is and as qualified as he is, Stillwater has a small problem with listening to others tell him how to do his job. Since his position gives him considerable authority and even more autonomy, the need to play well with others is not as vital as it once might have been and he clearly takes advantage of it. As a result, he is occasionally assigned a liaison with different agencies that has the real job of watching him and making sure he doesn't "get in the way", seldom realizing that his getting in the way is what would get the job done.
Luckily for those whose lives depend on his doing what he does better than the rest, Stillwater doesn't wait for permission or clearance or explanations or cooperation. He knows where he needs to be and goes there, letting the liaison decide if he or she can keep up.
Interestingly, and quite understandable when one considers the horrific viruses and bacteria he sometimes has to face, Stillwater takes a moment or two before every close encounter to vomit. He doesn't want to but he does. It helps him. It also scares the daylights out of those working with him as they have to wonder just how good is this guy who gets nauseated from fear. Stillwater, however, knows that once he literally gets it out of his system, he is able to perform.