Iris Incredible

Vicar-Vic-Farbstein, seventeen, resident of Eugene, Oregon, an average high school student in every way, happens upon an alien who has come to Earth in search of warriors to defend her world. With a long, unpronounceable name, he calls her Iris, with her blessing. Iris has abilities-flight and strength-and soon, the NSA discovers what she can do. Led by Agent Randolph Haynes, he urges her to keep a low profile and blend in.
Blending in, though, isn't something Iris can so readily do, as the destroyer of her world, Kherter, a fearsome giant of a man, sends his forces to Earth to destroy her as well as enslave mankind. Iris manages-barely-to beat them back the first time, and in doing so, reveals herself to the world. Vic accepts her as a friend, and so do many others at first. The press dubs her Iris Incredible, and she's hailed as a savior, a mantle she is unwilling to assume.
Her only goal is to find someone who can help her in her own cause. When Kherter and his forces return to ravage downtown Eugene and subsequently threaten the world, human nature takes over. Trust turns to mistrust and fear, and Iris becomes a pariah, as does Vic. Soon, social order breaks down as the worst of human nature comes to the fore. In spite of the public's antipathy, Vic and Iris take on Kherter's forces in one, final, all-out assault.
Iris knows what she has to do, as does Vic, and they engage in a battle that will determine the future of mankind.