Marionettes are puppets controlled by strings and were popular at the courts of the French monarchy.
The puppet shows satirized gossip and could be embarrassing to anyone involved in scandal.
When money was slipped to the puppeteer to keep him quiet, or to influence him to embarrass someone else, it was said that the person offering the bribe, and not the puppeteer, was the one pulling the strings of the marionette.
The use of behind the scenes influence is often called “pulling strings”.