When I read your thread, my first idea was "Peter Wiggin." A genius-level kid who's not a scientist, but a student of politics and sociology as well as an expert at manipulating people. Of course, Peter eventually turned into a good guy because he wanted to rule the world rather than destroy it. But Damren upthread gave you an excellent genius/motivator as well.
In all, i think to make this work right, you need to give the kid a motivation as well as genius. What makes him tick? Why does he do the things he do? What does he want beyond "more stuff?" There's a lot to play with.
Money-Man. Cam Sardwick has always idolized his father Jim, a small-time investment manager in the Midwest. When he was 4, Cam asked for an adding machine for Christmas. His parents cave him a toy computer, and when Jim Sardwick moved money from his home office, Cam sat right beside him. When he got tired of his toy, Cam would look over his father's shoulders, watching money move from one account to another. His eyes would eagerly devour spreadsheets. When Cam's mother Cecile died, the victim of a drunk driver, Cam and Jim retreated further into the numbers. Climate swaps. Credit derivatives. Synthetic CDOs. By the time he was 8, Cam wheedled his father into giving him seed money and his own trading account. By the time Cam was 10, his father watched in wonder as his son skillfully executed trade after trade, quadrupling his seed money. By the time he was 12, Cam was the silent partner in Jim Sardwick's investment brokerage. Father and son bonded to the music of CNBC as Cam learned not just about money, but about what the numbers represented -- commodities on the one hand, speculation on another, management of risk here. But most important, Cam learned that money represented dreams and hopes. Life itself. That by manipulating these numbers, he could bring harm or hope to another human being without ever leaving his house.
But by the time he was 15, Cam found finance too easy. He could make a million dollars, or a hundred million dollars, in a few hours, by barely exercising himself. Meanwhile, Cam's father Jim drifted away from him, seeking love or companionship in a succession of everchanging "companions" whom Cam did not bother to know. All that mattered was the family business -- Cam's business in all but name, now -- and one other thing.
Cam wanted something more than mere manipulation of numbers. Then he remembered ... at the end of every number was a dream. And at the root of every dream was a person. Where other investors might turn to angel investing -- finding a worthy idea and helping somebody else grow it -- Cam's tastes turned out less benign.
Cam is an angel investor alright, putting his money to work on others' behalf ... but he has no interest in helpign somebody start yet another gift shop on Main Street or build the latest social-networking software. There is no thrill. No joy. No vicarious notoriety.
Instead, Cam found himself investing in other criminals' enterprises. His ability to see pattern and sense in the legitimate financial world has proven quite profitable in funding criminal endeavors. Through a series of dummy corporations and shell companies, Cam "invests" in a series of criminal enterprises. Though he never dirties his own hands, Cam takes a secret thrill in learning that one villain or another has successfully pulled off a heist, or threatened the world, or similar ... and that he helped finance it.
Cam ostensibly does this for the money, and he does indeed profit. But mostly, he likes seeing the big splash. When one of his "investments" matures -- that is, unleashes its horror -- Cam devours the news of it excitedly, whether in media or through the stories his own agents relay back to him.
In the underworld, Cam's real identity is unknown. Instead, he is the shadowy, Money-Man, all too willing to loan money, or even become a criminal's silent partner. Some wonder who he is or why he does what he does ... but most simply accept his money. If a scheme fails, Money-Man simply does not finance a villain again, but there seem to be no reprisals. But woe betide the villain who succeeds, but does not give Money-Man his cut.
It turns out that all sorts of powerful people owe Money-Man a favor ...