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.
Six years of daily instruction with the wiedly disparate fields of study and not much time allowed for being anything normal has instilled in Midway two things. The first is far more knowledge on an incredible range of subjects. The second is an intense desire to be 'normal' which will prove to be difficult because Midway really has no idea what normal is. He just knows beyond any doubt that he does not have it nor has he ever.
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 and while it becomes obvious to Midway that Cerberus will do anything to get him and others like him, Cerberus quickly learns that Midway is not just a freak experiment - he can be when pushed a force to be reckoned with.
And then there will be his sister that he learns about and who will join him. She too is nothing to take lightly.