Talmadge 'Tal' Bannerman is an agent with the Department of Homeland Security.
According to information given us in one of the two recorded adventures, he and his work partner, Carl Wrigley, have been with the DHS for a relatively short time but neither are new to public service nor to putting their lives on the line in defense of the country. In Bannerman's case, he comes to DHS after a successful period of time with the Epidemic Intelligence Service, a branch of the CDC, organized in 1951, "with the purpose of investigating disease outbreaks that are beyond the control of state and local health departments, enforcement of interstate quarantine regulations, and providing epidemic aid at the request of state health agencies". Working there, Bannerman went "more than once into hostile territory" where he "performed well under the rigors of war and disease in Afghanistan, Ethiopia, and the Sudan. As well as being an epidemiologist, [he] studied veterinary medicine for a time".
We get very little information about Bannerman other than that above in the short tales we have. We know that he is happily married to a woman named Bridget. He has at least one sibling, a sister, and he is considered handsome enough "to pass as a TV newscaster".
While he is willing to put his life in danger for others, he is not always thrilled with the idea. When told he and Wrigley had been chosen for a very dangerous mission with little chance of success and a huge likelihood of death, his first response was pretty much "okay, why us?" To give him credit, though, when told why, he nodded in agreement and was then committed to the task.