To some commentators, Top Gun: Maverick (2022) was an exercise in “fan service.” Tom Cruise made the film he thought his audience wanted him to make. There were, as in the original, lovingly shot dogfights over the ocean. Val Kilmer, the icy yin in Top Gun to Cruise’s hot-headed yang, returns to the screen, in his last film role, to give the movie an emotional core. Maverick’s co-pilot dies in the first film so, by the second, his son, who blames Cruise for his father’s death, has become a fighter pilot himself, thus providing a personal conflict to be resolved by the end of the movie. There is a love interest. There are shots of Cruise riding a motorbike in a bomber jacket. There is, in short, everything middle-aged men in cinemas across the world need to briefly feel as if they were twelve years old again.

If fan service is the recreation of an original property sufficiently faithfully to allow the audience to re-experience their earlier emotions, to riff on earlier events, and to answer the question of what happened next, Top Gun: Maverick is fan service par excellence. Perhaps that’s why it was so successful, becoming 2022’s second most popular film, and the highest grossing of Cruise’s career.

Fan service is not a recent phenomenon. Only a year after The Three Musketeers (1844) was published, Dumas published Twenty Years After, in which his protagonist D’Artagnan is once again involved in a dastardly plot and must put the band back together to defeat the machinations of Mordaunt, the son of Milady de Winter, the femme fatale of the previous novel. As before, there is a dubious cardinal, there is swashbuckling and, in the end, there is justice—all the elements that made the original so successful.

Perhaps the greatest act of fan service, however, was performed sixty years later when Sir Arthur Conan Doyle re-animated Sherlock Holmes. Having come to believe that the stories were a distraction from the serious, important works he thought he could write, Conan Doyle sends his hero over the edge of the Reichenbach Falls in 1893’s The Final Problem, having hastily invented Professor Moriarty as a worthy nemesis. Eventually, the public clamour led him to return to his famous detective, with The Hound of the Baskervilles (implicitly set before Holmes’s demise) in 1901 and The Return of Sherlock Holmes in 1903, a collection of short stories, the first of which, The Adventure of the Empty House, explains how the detective cheated death. Four more anthologies and another novel followed.

Like his peers, however, Conan Doyle was reticent about his creation, providing the reader with information about his professional life, but not much backstory. We know that Holmes’s ancestors were “country squires” and that he has been to university, but little else. We know that he has solved some crimes that are not detailed in the stories Watson narrates—one being the mystery of The Giant Rat of Sumatra, which is tantalisingly alluded to in The Adventure of the Sussex Vampire as a story “for which the world is not yet prepared.”

But where Conan Doyle stood aside, others stepped up. There are at least two novels telling the story of the oversized rodent and countless others reciting tales that escaped the doctor’s notice. Chris Columbus provides the history of Holmes’s schooling—and provides a basis for his smoking habit and, indeed, for Moriarty—in his 1985 film The Young Sherlock Holmes. A character who, to his creator, had no existence outside his stories has, through the efforts of others, become a fully-fledged person with a past and a future (1942’s Sherlock Holmes and The Voice of Terror sees him take on the Nazis).

This completist tendency is not new. A lot of Classical Greek literature either extends (The Oresteia) or fills in gaps (Sophocles’ Ajax) left by Homer. Aeneas is a minor character in the Iliad, albeit one who enjoys divine protection and is destined to be King of the Trojans. The Romans decided that this led him to be moved around the Mediterranean against his will so his descendants could found their city. To the anonymous author of the 9^th-century Historia Brittonum, one of his lesser-known progeny would go on to found Britain. Later, Medieval Oxford scholars, engaged in the traditional rivalry with Cambridge, claimed him as the founder of their university.