One character we hear about but don't meet in Magruder's is Susannah, the Flamingo Girl. She is the one who tells Whitey about the sudden death of Count Orloff... initially the story seems implausible but, as Whitey notes, "Flamingoes don't lie."
Susannah was inspired by a real person named Ella Harper. Harper was born in Tennessee in 1870 with a condition called genu recurvatum--a joint deformity in which knees bend in the opposite direction they usually do. Today, this condition can be dealt with via surgery and physical therapy.
Ella worked the sideshow circuit under the name, "The Camel Girl." She was displayed as part of W.H. Harris's Nickel Plate Circus for $200 a week--a fine salary for the day. But eventually she left the circus to return to Tennessee, marry, and attempt to start a family.
A blogger named Ray did a wholly impressive job of hunting down information about Ella. So if you are interested in learning more, I wholeheartedly recommend this page, which documents his exhaustive search for information about Ella's life. Well done, sir!
As for Susannah, I'd hoped that she could play a bigger role in the novel, but my editor told me if I added any more characters, she'd throw my book out the window. (She put it more nicely than that, but I got the message.) I hope one day I'll get to do a sequel, and then you can meet the Flamingo Girl.