Sub-plots are not essential in very short works, where all words are concentrated on the central narrative. For the most part, however, sub-plots serve the important purposes of illuminating the main plot and maintaining the attention of our readers.

INTERWOVEN THREADS

It may be helpful to think of plots and sub-plots in terms of a tapestry. The fabric of the main theme is designed to attract the eye and focus the attention, but very often the effect is heightened by, or even depends on, complementary or contrasting colours and textures woven subtly into and around the main theme.

In the same way, sub-plots, though of merely secondary importance, are invaluable in setting context and adding perspective.

They must not to detract from the main theme, so it is important that their colours are not too bright or their textures too heavy.

Sub-plots may be small works of art in their own right, like the tiny embroidered cat that lurks in the shadowy corner of a vast canvas, but they must also have some discernible connection with the main theme if the whole piece is to be properly unified.

CHARACTER LINKS

By far the most familiar means of connecting plot and sub-plots is to make one or more characters common to both. This has the effect of making the story seamless, insofar as the reader may trace all the threads of the narrative to the common root that is the central theme.

This is not to say that the links between plot and sub-plot need necessarily be clear from the outset. The reader may take great pleasure in trying to solve the puzzle of how two seemingly disparate themes are to be knit together, greater pleasure still in the moment when the writer's surprise is revealed. Charles Dickens' Our Mutual Friend is an excellent example of this, in which two seemingly unrelated characters, one presumed dead for most of the book, eventually turn out to be one and the same person.

LINKS VIA SUBTEXT

However writers have become increasingly interested in exploring the idea of sub-plots or parallel plots that are linked exclusively at the level of events or subtext. For example, radio and television programmes and series often explore a single premise (such as poverty is the root cause of all social evils) or event through characters and stories that are connected only at the level of subtext. (There is no main plot here beyond the premise itself, but only a series of sub-plots that seek to illuminate the premise.)

Arguably, sub-plots are at their most satisfying when they are both complementary and contrasting. The bar-room scenes in Shakespeare's Henry IV provide an outstanding example of this. Their high comedy leavens the serious action of the play and yet, for all the comedy, this is serious action with an important point to make: in short, the young Henry V is seen to inhabit two distinct lives that illustrate and heighten the conflicts between his roles as young man and king-to-be.

BEGIN WITH THE SUBTEXT

Perhaps the task of devising sub-plots is best begun at the level of the subtext.

Our discussion of subtext concluded that it is essentially the truly inspirational, multi-faceted secret that throws piercing light on every character and event in the plot without ever emerging from its inscrutable veil.

In other words, if we stand above the plot, at the level of what we are actually trying to say, we can more clearly see how the interests of our premise can best be served by sub-plots.

So, say, if we are exploring the premise that poverty is the root of all social evils through the journey of a central character from deprivation to crime and punishment, we will be well placed to see the pivotal points for the appendage of sub-plots that heighten or lighten the main theme.