Artemis Fowl, Book 6: The Time Paradox

Twelve-year-old Artemis Fowl is a millionaire, a genius, and, above all, a criminal mastermind. But even Artemis doesn't know what he's taken on when he kidnaps a fairy, Captain Holly Short of the LEPrecon Unit. These aren't the fairies of bedtime stories; these fairies are armed and dangerous.

Artemis thinks he has them right where he wants them . . . but then they stop playing by the rules.

Stay back, Human.

You don't know what you're dealing with.