Artemis Fowl and the Time Paradox, by Eoin Colfer

Colfer does such a good job with the Artemis Fowl books.  They are funny, unpredictable, imaginative, and ethically complex.  Time Paradox is particularly nifty as the reader gets to see Artemis as an 18-year-old, who is growing both a heart and a conscience, pitted against himself as a 10-year-old morally bankrupt, single-minded master criminal.  Artemis the Elder is trying to find the cure for a fairy-borne illness that is killing his mother by returning to his own past at a juncture when Artemis the Younger sold the last surviving silky sifaka lemur to a group of extinctionists.  Enn Reitel is a great reader.