Artemis Fowl: The Atlantis Complex (Artemis Fowl No. 7)

Captain Holly Short is unconvinced, and discovers that Artemis is suffering from Atlantis Complex, a psychosis common among guilt-ridden fairies - not humans - and most likely triggered by Artemis's dabbling with fairy magic. Symptoms include obsessive-compulsive behavior, paranoia, multiple personality disorder and, in extreme cases, embarrassing professions of love to a certain feisty LEPrecon fairy.