Meet Dennis Cheng, the longtime Clinton aide in charge of raising hundreds of millions for Hillary’s presidential run. Dennis Cheng, the finance director of Hillary Clinton’s presidential campaign, the man behind what has been predicted to grow to a $2 billion operation, is serious, soft-spoken, unflappable, and fiercely loyal to his boss. He is never quoted in the press. He doesn’t participate in profiles, won’t be interviewed, and doesn’t head to cable TV to defend Hillary Clinton against the Republican onslaught. In a political-media sphere in which contact with the Clintons can be a golden ticket to every green room...