(1) A term describing food that is dark, rich, chocolate, spicily piquant or stimulating it is "deviled." Means a highly seasoned, chopped, ground, or whole mixture that is served hot or cold. Many foods, including eggs and crab, are served "deviled."
From the Oxford English Dictionary – the 1786 reference is the first use of this word in print:
"Devil…A name for various highly-seasoned broiled or fried dishes, also for hot ingredients. 1786, Craig "Lounger NO. 86 ‘Make punch, brew negus, and season a devil.
(2) The earliest use of this culinary term was typically associated with kidneys and other meats, not stuffed eggs.
(3) The term "deviled" referring to meat, fish, and cheese spreads, is somewhat different. Spiced potted meats have been popular for centuries. William Underwood introduced his famous deviled ham in 1867.
James Boswell (1740-1795), Samuel Johnson’s biographer, often referred to partaking of deviled bones for supper. In a biography published in 1791, James Boswell referred to partaking of a dish of “devilled bones” for supper. The bones were generally those of cold poultry, game or beef. The pieces of meat were covered with what was then called devil sauces. NOTE: This may be the earliest published use of the word “devil” as a cooking term meaning “to cook something with hot spices or condiments.” Most Food historians believe that the term was adopted because of the connection between the devil and the excessive heat in Hell.