As someone who spent countless hours with his adolescent nose buried in the pages of The Complete Illustrated Strand Sherlock Holmes (Facsimile Edition), there are few activities that give me more pleasure than comparing, contrasting, and critiquing the many cinematic faces of The World's Most Portrayed Literary Human. Interpreted by more than seventy-five separate actors, Conan Doyle's legendary detective has been kneaded into countless permutations, all with varying levels of faithfulness to the original.

Robert Downey, Jr.'s Steampunk Sherlock? Love him, but can't shake the feeling that he's really just a charmingly 19th Century version of Tony Stark. What about Basil Rathbone's revered Classic Sherlock? Certainly captures the deerstalker-capped, hawk-nosed mastermind of Sidney Paget's brilliant Strand illustrations, but his Holmes is cardboard thin, reducing the occasionally unsettling moral gymnastics of Doyle's hero to an easily marketable (but inaccurate) purity. And what of Sherlock as Madman? Or Sherlock as Mouse? Young Sherlock? Or even Stupid Sherlock? Not without their advocates, I suppose. But faithful? Hardly.

For a hard-core fan(atic) like myself, Jeremy Brett's turn in Granada's mid-80's series is so pitch-perfect that it might actually be better than its inspiration—as complex and complete a characterization as one could hope to see. Yet, "Sherlock," the BBC's recent reimagining that places Conan Doyle's legendary protagonist in modern-day London, has brought me to an important realization. While its Holmes—a thorny, often unpleasant vision of Holmes-as-Misanthrope brilliantly captured by the magnetic Benedict Cumberbatch—is never a true threat to Brett's crown, the series does offer its audience something that the Holmesian Universe has long been seeking: a definitive Dr. John Watson.

Played by Martin Freeman, whose impending debut as Bilbo Baggins in Peter Jackson's The Hobbit: An Unexpected Journey is about to transform him into a household name, Sherlock's faithful companion is neither the bumbling fool so often portrayed in the early years nor the superfluous sidekick. In fact, Freeman's Watson is the perfect foil to Cumberbatch's Holmes, as gentle, self-effacing, and sacrificial as his companion is brash and narcissistic. And it is the very starkness of this contrast that highlights the essential role Watson must play in the Holmesian mythos.

Despite Holmes' repeated (often inexplicably unpleasant) attacks on their friendship, Watson remains loyal; while mystified, and even wounded, by his friend's calloused, belittling manner, the good doctor refuses to mistake that behavior for the sum total of Holmes' character. And while it can be difficult for readers and viewers alike to understand why he willingly tolerates such spitefulness, the tolerance itself speaks eloquently to the nobility of his spirit and perhaps more importantly still, the nobility of the man he has befriended.

The greatest obstacle confronting Cumberbatch's Holmes—perhaps the greatest obstacle Sir Arthur faced in the creation of his legendary character, as well—is the risk of bringing to life a man whose foibles and flaws leave audiences cold. True, Holmes' intellectual prowess and extraordinary powers of observation are a joy, particularly in Conan Doyle's earliest stories. But if those powers are attached to a man as deeply unlikable as he is brilliant, how long can we be expected to tolerate him? And that is precisely where Watson comes in.