Jon Jericho is an agent for the American President.
When we first meet him, he is temporarily assigned to a Delta Force detachment, leading a mission in ISIS controlled area of northern Iraq to rescue a captured American journalist. The mission had gone according to plan, the hostiles were eliminated and the reporter freed. Then a 12-year-old zealot they had not counted on got off one shot at the evacuating Jericho, codenamed Hunter, and that bullet skirted the body armor and did considerable damage to Jericho's hip.
With his Special Forces career over and his having no desire to take up a desk job, Jericho opted to return to the States to be reunited with his girlfriend of several years, Justine Vickman, the Chief Medical Examiner for Washington, DC. Also playing a major role in Jericho's life is her son from a previous marriage, Micyl, a very special young boy with a severe case of autism.
It is from her thinking of him that we get a good idea of what he looks like. "She thought he was more 'cute' than handsome. He was tall, just north of six feet, with bottle-green eyes that were a much deeper shade of emerald. He was also a man who carried with him an inner strength that could not be seen nor heard--a presence of command that came off of Jon like something warm and alive, an aura."
His connection to the President and the subsequent offer of a special operations job for the White House might not have come had Vickman not run afoul, through her duties as medical examiner, of a very ambitious and unscrupulous individual, the details of which make up the first recorded adventure.
The offer that the Chief Executive would make to Jericho in the Oval Office was "to head a team of specialized people to do what it was you did as a Delta. You'd be working for the administration and under the guidance of the CIA and FBI directors, both on foreign and domestic situations. ... Though you'll get black-op directions about what needs to be done though the directors, you will work as an independent group with your own people. You will contact me directly on mission progress. You will work with other units, if necessary. You will be my eyes and ears."
The team that Jericho would put would be known as the Centurion Group.