“The Red and the Black” by Stendhal (post 10): At the end, Julien Sorel hears a voice that he explicitly recognizes as the voice of an alternate personality.

The protagonist, Julien Sorel, has been convicted of premeditated, attempted murder. He receives a death sentence, which he refuses to appeal. In jail, awaiting the guillotine, he speculates about what might have been, if things had gone differently. His thoughts are interrupted by a voice, which he explicitly recognizes as the voice of an alternate personality:

“…All my stupidities would have been forgiven, or more likely thought worthy. A man of high repute, enjoying high life in Vienna or London.

“ ‘Not exactly, sir: you’ll be guillotined in three days.’

“Julien laughed heartily at his own mordant wit. ‘Really, we all have two personalities,’ he thought. ‘What devil thought up that nasty joke?’

“ ‘All right! Yes, my friend, guillotined in three days,’ he replied to whoever or whatever had interrupted him” (1, p. 464).

When Julien asks “What devil thought up that nasty joke?” he seems to be implying that he has more than two personalities, and that he is not sure which of his other personalities was the devilish joker.

He says not only “whoever,” but also “whatever,” because not all alternate personalities are perceived as ordinary people; e.g., some may be perceived as devils or angels.

1. Stendhal. The Red and the Black: A Chronicle of 1830. Translated by Burton Raffel. New York, The Modern Library, 2003.