Millet is the fair's director of functions. This means he has a big part in choosing all the cool stuff on display at the exhibition.
When things start looking grim for the fair, it's Millet who steps up to help promote it and increase attendance through a series of exotic events: boat races in the basin of the Court of Honor, swim meets in the lagoon, and a dance for the great Midway ball.
And Millet succeeds:
The ball and Frank Millet's other inventions imparted to the exposition a wilder, happier air. (3.17.22)
Millet's also an extremely close friend of Burnham, and in 1912 Burnham learns the fate of his buddy while he's aboard the Olympic. Millet's ship—a little boat called the Titanic—has struck an iceberg in the Atlantic. Millet would be along the fifteen hundred people aboard the "ship of dreams" to drown.