Subplot (also called counterplot) - a secondary or minor plot within a play or other literary work which may contrast with the principal plot, highlight it, or be unrelated. It involves characters of lesser importance than those involved in the major plot.
The term is formed by joining the Latin sub, meaning “under,” with plot, whose etymology is discussed under that listing.
Subplots were very common in Tudor and Jacobean drama.
In Shakespeare’s King Lear, there is the subplot concerning Gloucester and his sons Edmund and Edgar: Edgar attempts to convince his father of the lie (with Edmund’s complete compliance) that Edmund, who is illegitimate, is trying to murder him. This subplot dealing with the father’s persecution of one son and the ingratitude of the other is juxtaposed with King Lear’s struggles with the villainy of his daughters, Regan and Goneril, and the innocence of his daughter, Cordelia.