Margaret Atwood, in Negotiating with the Dead: A Writer on Writing (2002), says that all fiction writers have at least two personalities

“I grew up in a world of doubles…a superhero was nobody unless he had an alter ego…Yes, there were earlier examples of disguises and doubles. Yes Odysseus disguised himself to reenter his halls in Ithaca; yes, in the Christian religion God came to earth as Jesus of Nazareth, a poor carpenter. Yes, Odin and Zeus and St. Peter wander the world as beggars in legend and fairy-tale…But it was the Romantics, par excellence, who fixed this doubleness in the popular consciousness as a thing to be expected, and expected above all of artists…

“As for the artists who are also writers, they are doubles twice over, for the mere act of writing splits the self into two. In this chapter, it is therefore the doubleness of the writer qua writer I will discuss…

“What is the relationship between the two entities we lump under one name, that of ‘the writer’? The particular writer. By two, I mean the person who exists when no writing is going forward…and that other, more shadowy and altogether more equivocal personage who shares the same body, and who, when no one is looking, takes it over and uses it to commit the actual writing…

[When she writes things that are out-of-character] “Who was I then? My evil twin or slippery double, perhaps. I am after all a writer, so it would follow as the day the night that I must have a slippery double…

“All writers are double, for the simple reason that you can never actually meet the author of the book you have just read…

“There has been a widespread suspicion among writers—widespread over at least the past century and a half—that there are two of him sharing the same body, with a hard-to-predict and difficult-to-pinpoint moment during which the one turns into the other. When writers have spoken consciously of their own double natures, they’re likely to say that one half does the living, the other half the writing…”

Atwood elaborates on the above in her twenty-seven page Chapter 2, which is titled: “Duplicity: The jekyll hand, the hyde hand, and the slippery double, Why there are always two" (in every writer).

Yet, like the dictionary of literary terms whose entry on “the Double” was quoted in a recent post, Atwood seems not to know that what she is describing about the “double” nature of writers is that they have a normal version of multiple personality.