Wall and the Wing Series by Laura Ruby

A few, nicknamed leadfeet, are forced to forever spend their lives closer to the ground. But one night, a girl named Gurl--a leadfoot, an orphan, a nobody--discovers that she can do something much better than fly.She can become invisible.Along with a new friend, a boy named Bug, Gurl begins a quest that takes her on a wild ride through the magical city, all the way to the handsome but lethal Sweetcheeks Grabowski--the gangster who holds the key to Gurl's past . . . and the world's future.

In a city filled with wonders, one girl can do the most wonderful thing of all.Georgie is special.Not only is she the one person who can disappear at will, but since she found her parents, she's become The Richest Girl in the Universe... moreIn a city filled with wonders, one girl can do the most wonderful thing of all.Georgie is special.Not only is she the one person who can disappear at will, but since she found her parents, she's become The Richest Girl in the Universe. She may be special, but is she lucky? Her parents have forbidden her to vanish, her new school is full of snooty heiresses, she's had a growth spurt that makes her as graceful as a grizzly, and her best friend in the world, a belligerent boy named Bug, seems to have abandoned her.But adventure is just around the corner, as a madman who calls himself The Chaos King has Georgie and Bug in his sights. In their efforts to save themselves from his insane plans, Georgie and Bug discover some of the amazing secrets of the city they love. Their journey will lead them to confront a pack of blase vampires, a living lion of stone, a disgruntled teenage poet, a candy-loving sloth, The "Second" Richest Girl in the Universe, a fussy man named Mr. Fuss, and finally, the brink of the unimaginable. . . . less