The Time Paradox: Artemis Fowl, Book 6

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."