Artemis Fowl and the Atlantis complex. Eoin Colfer. 2010.

Criminal mastermind Artemis Fowler has summoned an elite group of fairies to Iceland. But when he presents his invention to save the world from global warming, he seems different. Something terrible has happened to him. 

Artemis Fowler has become nice .

The fairies diagnose Atlantis Complex (that’s multiple-personality disorder to you and me) - dabbling in magic has damaged his mind. And now the subterranean city of Atlantis is under attack from vicious robots and nice Artemis cannot fight them.

Can fairy ally Captain Holly Short get the real Artemis back - before the mysterious robots destroy the city and every fairy in it?