“V.” by Thomas Pynchon: Protagonist always speaks of himself in third person, and has “repertoire of identities” with different preferences. 

“Herbert Stencil, like small children at a certain stage…always referred to himself in the third person. This helped ‘Stencil’ appear as only one among a repertoire of identities. ‘Forcible dislocation of personality’ was what he called the general technique…for it involved, say, wearing clothes that Stencil wouldn’t be caught dead in, eating foods that would have made Stencil gag, living in unfamiliar digs, frequenting bars or cafés of a non-Stencilian character; all this for weeks on end; and why? To keep Stencil in his place: that is, in the third person” (1, p. 51).

Although called a “technique,” the above would seem to describe a person with multiple personality, whose host personality is Herbert Stencil and whose alternate personalities are the “repertoire of identities.”

Alternate personalities typically refer to each other in the third person, and may differ from each other in clothing styles, food preferences, etc.

But since the “repertoire of identities” is not labelled “multiple personality,” I do not know whether the author recognized it as such.

I am only at the beginning of the novel, and will read on.

1. Thomas Pynchon. V. [1963]. New York, Bantam Books, 1984.