Booker (Royce Joshua Woodruff, but he prefers going by "RJ") appears to be one of the campus bookies. Oddly enough, he doesn't appear to be associated with the bookie ring.
He mentions to Mule that the Las Vegas odds on their upcoming sim run aren't what he would expect.
He is approached by Tweak to help selling the info she got on the Combat Finals. Later, he is seen accepting bets besides the other bookies in Arena 99.