The term, “Sidekick” comes to us from gamblers testing their luck at the card table in the 1600’s. It meant what we now call an “ace in the hole,” or a power card held in reserve for an appropriate time.
Many novels utilize the services of this character called sidekick with great effect. Most often they contrast with the protagonist, but in a nonthreatening, possibly even humorous manner. The secret to the Sidekick when you write fiction? He’s an interactive prop against which the hero bounces.
His purpose is to enhance the characteristics of the hero and possibly offer comic relief. He also gives depth to the plot and other characters. Often a main goal is to provide counsel and/or information to the good guy. The Sidekick is also assigned those duties unsuitable for your hero or beneath his status. Another typical function is to save the hero’s hide at those times when your protagonist appears most at risk. Regardless his duties, the Sidekick participates in almost all the hero’s exploits, except of course, those of a physical nature. To his chagrin, the Sidekick never gets the girl.
Your sidekick should be developed as well as any other important character. He, like his heroic counterpart, requires motivation, he must stay consistent to his personality and have something likable about him.
His personality is typically drawn as smart, shy or even cowardly and a bit neurotic, though this stereotype is changing in literature. These days, the sidekick can be as powerful, or more so, than your hero in some ways. Think of Han Solo in Star Wars. He got the girl even before Luke knew Leia was his sister. (Come on now, as Leia was Luke’s sister, this is the exception to the rule about sidekicks and the story’s love interest mentioned above.) Regardless, the Sidekick’s skills compliment the hero’s. For example, consider Sherlock Holmes and Dr. Watson. The good doctor’s personality made Sherlock a more palatable character.
The Sidekick is often differentiated from the protagonist by one or more characteristics. In sci fi, for example, they are often of another species entirely. In other genres, they can differ by any number of factors which might include economic position, education, culture, race or even gender. By the way, a sidekick never has a physical relationship with the hero, which I’ll explain in a moment.
The primary relationship between the main character and the sidekick is trust and loyalty. Their bond is unbreakable, though the reader needn’t necessarily know this. Should the hero and his sidekick part for whatever reason, it can make for an exciting scene when, at his darkest moment, the hero is saved by the unexpected return of the contrite sidekick. That bond also is why the hero and his sidekick can never have a physical relationship. That can create too many opportunities for this trust to bend and break. Further, if you’re not careful, a physical relationship may even move one or both characters into a different character type altogether. This trust also is why your villain will never have a sidekick. Bad guys and their henchmen are notoriously untrustworthy.