Sandy Drescher: Doesn't the evidence runs the other way [I ask you]. The imagined  reader is one of most author's collaborative 
others. When the desired reader is the author's intellectual double, the idea of  collaboration has been rejected [but perhaps not 
entirely  convincingly. ]

Jansy Mello: Sandy, I couldn't agree more! The imagined reader is one of the collaborative others in 'real' life, even when described as the author's double... 

Charles Nicol's examples and his explanations are excellent concerning SB's direct query (related to pairs in VN fiction). I have no VN work at hand to refresh my memory, but the opposite, or his refusal of propitious colaboration might have been adumbrated in LATH by in V's description of his secretaries. 

Steve, the presentation of the book that inspired your query (I'm using a borrowed computer and feeling rather constricted to write or move around to explore it) did not impress me, no, not at all.  Nor did the author's theses about collaborative couples, or his arguments against "the lone genius" (I'm sure that geniuses are influenced by significant others, but I wouldn't consider their participation so literally, with very few exceptions.). Your exploration is interesting by itself...