Partners in adventure have existed in fantasy and its Taproot Texts since the time of Gilgamesh. A distinction needs to be drawn between (a) duos whose contrasting partners may provide readers anything from light relief to revealing insights about human interactions, but who in the end remain together in order to continue adventuring, and (b) partners whose main function is to dramatize profound oppositions, or to represent (> Jungian Psychology), in terms of Story, the great interior battles of the Soul on its Quest or Night Journey towards self-Recognition. In this encyclopedia we use the term "duos" to refer to the former category: duos are equal partners in adventure.
Don Quixote and Sancho Panza, the indissolubly married opposites in Miguel de Cervantes's Don Quixote (1605-1616), might logically be so described, but the burden of their interaction – the profundity of the vision of human life they represent – is inadequately conveyed by the thought that they might form a duo, like Sherlock Holmes and Dr Watson. Arthur Conan Doyle's famous pair are a paradigm duo, and centrally affected the modelling of duos in popular literature from the end of the 19th century.
The distinction between duo and Shadow continues to be valid throughout the 20th century. Frodo and Samwise, in J R R Tolkien's The Lord of the Rings (1954-1955) interact profoundly, but not as a duo; Fafhrd and the Gray Mouser, in Fritz Leiber's lifelong Fafhrd and the Gray Mouser sequence, may also interact on a profound level, but they serve more saliently as warrants that their mutual tale will continue. The Fantasyland they inhabit, and the Heroic-Fantasy adventures they enjoy, are both conducive to the creation of duos and strengthened when duos appear within them. Within template structures, duos have proved to be an essential building block: split plots, trilogy-management, rescue missions, fights, reconciliations, hidden missions, infodumps of backstory, and any number of Plot Devices – all are easier to fabricate when pairs are involved, and when, as often, one partner needs to be told what the other partner has learned. They may also shape a group of Companions, or a Seven-Samurai gathering.
Holmes and Watson have provided a model for one particular category, in which a genius of some sort is paired with a Sensible Man, who may tell the tale. There are many other categories. There are Defiant Ones, pairs locked together (sometimes in a Dirty Dozen squad) who, while escaping a mutual fate, and while fighting like cat and dog, eventually become intimate. There are Nick and Nora duos – from the protagonists of The Thin Man (1934) by Dashiell Hammett (1894-1961) – who advance the plot (and their relationship) through cross-talk, a banter of solidarity against a conspiring world. There are Odd Couples, and Robin Hood and Maid Marian duos, and Batmans and Robins, and reverse duos (whose partners do not know they are partnered), and dozens more. They are numerous because they are engines of Story. [JC]