Loki

“Sanity and happiness are an impossible combination.”
― Mark Twain

“Inside every sane person there's a madman struggling to get out," said the shopkeeper. "That's what I've always thought. No one goes mad quicker than a totally sane person.”
― Terry Pratchett, The Light Fantastic

“Men have called me mad; but the question is not yet settled, whether madness is or is not the loftiest intelligence– whether much that is glorious– whether all that is profound– does not spring from disease of thought– from moods of mind exalted at the expense of the general intellect.”
― Edgar Allan Poe, The Complete Tales and Poems of Edgar Allan Poe

“Damaged people are dangerous. They know they can survive.”
― Josephine Hart, Damage