Mark Midway is a genetic experiment.
That really is not a profession, of course. It is an origin as well as a state of being and it fits Midway.
He is in actual years age 12 but "his physical appearance and mental age are twice that". He was found, or rescued, at age 6 and brought to the Lifelong complex where he was "adopted" by a couple and spent the next six years there. During that time his tutoring was intensive and he proved that he could handle whatever was handed him.
Then came the invasion of the facility by agents of a very unpleasant secret organization known as Cerberus which wanted the research and him and would kill without hesitation to achieve both. They had not reckoned on how sharp Midway had become.
Now he on the run.