Jonathan Swift’s Gulliver’s Travels, published in 1726, marked the beginning of this movement. Not long after its publication, readers started to imagine its hero, Lemuel Gulliver, in circumstances that either were only briefly alluded to in the text or they themselves invented; the more shocking the revisions, the better. Many stories took the form of what was essentially “fan art.” For example, the famous engraver William Hogarth provoked and amused with a graphic representation of Gulliver getting a Lilliputian enema. Though outrageous, Hogarth’s rendering was consistent with Gulliver’s character, a play on the original hero’s delight with the size of his own excrement in contrast to the miniature world of the Lilliputian people. From the start, artists were using the form to explore social taboos and sexuality.

Hundreds more fan-authored works followed, including a touching if bawdy series of poems by Alexander Pope in which the shipwrecked adventurer’s wife—barely mentioned in the original—complains that her husband is never at home to do his duties by her. When Gulliver returns from his final adventure, he has become so disgusted with the human race that he hides from his family. The fan-written Mary Gulliver was, understandably, put out by her husband’s newfound abstinence.

In the 18th century, as now, fan fiction was usually more explicitly sexual than its source material. There was plenty to set the imagination on fire in Samuel Richardson’s 1740 classic novel, Pamela, about a lady’s maid on an isolated country estate who resists the overtures of her boss. But readers also liked to envision scenarios where she gave in wholeheartedly. One reader who was particularly obsessed with reconceiving Pamela Andrews as unchaste was Henry Fielding, Richardson’s fellow novelist. Critical of Richardson’s puritanical overtones, Fielding resolved to imagine his own Pamela, who was only pretending to be a shrinking violet to increase the desire of her lord. In Shamela, Fielding constructed an alternative set of letters where, in true sexy-supervillain fashion, Pamela and her mother lay out their plans to entrap the squire of the manor. Apparently unsated, Fielding went on to write Joseph Andrews, a full-length gender reversal in which Pamela’s naive brother resists the seduction attempts of an older, landowning lady, the original squire’s sister.

As the literary scholar David Brewer points out, an essential part of most expanded 18th-century universes was the unwieldy, enthusiastic, and self-selecting community of readers that they created throughout Europe—essentially, the AO3s of their times. Although instantly sharing and commenting on fan work weren’t quite as easy then as they are now, the 1900s did see a rise in literacy among the middle class, thanks in part to the Industrial Revolution making printing cheaper and postal-delivery systems more reliable. Most of the earliest novels were epistolary, which gave readers a more direct sense of communicating with their favorite characters. Some of these stories even went mainstream. Fielding was the E. L. James of his day, his breakout success supported by thousands of readers, most of them young women—not to mention quite a few men who weren’t willing to publicly cop to reading books about maidservants.