The word sidekick is often used to describe a personne who is helper of someone. Most often used as a term for a special buddy, helper, it is can be often found in Comic books, like Batman and his sidekick Robin are the most obvious pair.. The origins of the word are associated to crime rather than fantasy and comics. It was used to describe a close male associate, it first came into use in 1905. Often used by pickpockets to name their partner in crime. Kick’s were the term in early 1900s to describe a man’s pants. And their pockets were on the side of their kicks so if you fusion the two words together you get a sidekick.
The pickpocketing process would work like this, one man would bump into you then distract you by talking to you and then the sidekick would snatch something from you really quickly.