It's autumn of 1995. I'm eighteen, not more than a month into my first semester of college. I'm in the library, reading through the New York Times. I turn the page – and Sherlock Holmes looks back at me. That is, Jeremy Brett in his Sherlock Holmes costuming looks back at me. The caption reads, "Jeremy Brett, famous for his portrayal of Sherlock Holmes, dead at 59."

The wave of shock and sadness that washes over me is perfectly understandable. I grew up watching the Jeremy Brett/Edward Hardwicke BBC Sherlock Holmes series. Their Hound of the Baskervilles was the first televised Sherlock Holmes adaptation I ever saw (at age twelve), and it brought vividly to life the universe I had spent the last year immersed in through the medium of the written word. There's something weirdly symbolic about Jeremy Brett's sudden and early death taking place during the first month of my first year of college. It draws one of those lines between childhood and adulthood.

It's December of 2005. I'm sitting in bed with my laptop. It's late, but I've logged on to check e-mail and headlines. And I find Leo McGarry's face looking back at me. The headline reads, "John Spencer Dead at 58."

And I'm surprised by the jolt of sorrow that jerks through me. I once loved West Wing, and I like John Spencer's work in general, and fifty-eight is too damned young for anyone – but West Wing isn't Sherlock Holmes. It didn't impact my formative years, and I stopped watching two seasons ago. Under the circumstances, I'm surprised by the lump in my throat. It's just a TV show, I scold myself. And another, younger part of myself counters, But how will they ever finish the story now? with plaintive clarity.

This is a new problem, in the world of storytelling.

When the story exists only in the medium of the written word, the storyteller has complete control. Speech patterns, inflections, gestures, and character arc are completely under the control of the person with the pen. The words win. The author wins. In part because nothing is competing.

When a story is adapted for the stage, the power still lies in the written words and the person who wrote them. Hamlet is Hamlet, whether he is played by Garrick or Kean or Macready or Olivier. If the actor playing your Hamlet dies halfway through the run? or is too ill to perform? Why then, you get another one. The play's the thing. Hamlet is always Hamlet, and when Garrick died, Hamlet lived on.

As recently as the early days of television, it was commonplace to replace actors. The play's the thing; the characters are what counts; and no one will notice that Samantha Stephens' husband and next door neighbor look different in the colorized version than the black-and-white version. The actors are the portals for the words, and the author is still in charge.

When did it change? When did it become necessary to write out characters when their actors were no longer available? Somewhere along the line, the images in the TV screen became more real, and more integrated into daily life, than the far-removed words in the book or men up on the stage. The actor (executor) gained influence over the creation almost commensurate with that of the creator.

The story of Jeremy Brett and Sherlock Holmes illustrates the point perfectly.

It's not accurate to say that "Sherlock Holmes became Jeremy Brett", because Brett was always a character actor rather than a diva. And I have seen interviews with a gregarious and laughing Jeremy Brett (wearing an earring!) and that man is certainly not Sherlock Holmes. But it is true that the fate of Jeremy Brett influenced the fate of Sherlock Holmes. Of this Sherlock Holmes, in this adaptation.

Jeremy Brett died with six episodes still unfilmed. The BBC intended to do them all – in fact, spent considerable effort adapting the later, weaker stories that were harder to film – and very likely would have wound up with "His Last Bow", the story of Sherlock Holmes' service in the First World War and the way Conan Doyle chose to conclude the legend. The fans think that's where they were headed, at least, but Brett died with six episodes planned but not executed, and consequently impossible to ever execute, and so we don't know.

He was in fact so ill that Holmes scarcely appears in the last Sherlock Holmes mystery filmed. "I shall be away for some weeks," he tells Watson abruptly, in the first five minutes – and so his tenure as Sherlock Holmes ends with same abruptness.

"I shall be away for some weeks... in the highlands... and as for you, your patients might be encouraged by seeing you more often at your surgery."

"You know my methods... you can carry on very well. Don't worry! I shall be watching you—with my third eye!"

And Holmes is gone, off down the stairs and to the highlands. The rest of the adventure unfolds without him.

"My dear Holmes," Watson writes to the off-screen detective, "I had a most unusual experience..."

It's awkward, to be sure, but I appreciate the effort.

"I am sure my brother would be most happy to oblige the Prime Minister if he were here!" Mycroft Holmes tells an overly persistent government official. "But he is not. So he cannot." Heartbreaking. "But—" And the big man leverages himself out of the chair. "I suppose I can."

And Mycroft's case and Watson's link up (inevitably) and the result is an exceedingly well-crafted hybrid of two of the most awful of the short stories – a creation that becomes a broadly-painted and very enjoyable comedy. It's an unusual pairing, Mycroft and Watson, but both the actors and the characters carry it off just fine.

"You know my methods... you can carry on very well without me."

Am I glad they did not film a real ending? I don't know. I would have liked to have seen "His Last Bow" done by Brett and Hardwicke, and there would have been satisfaction in seeing the story come to its close. There's no satisfaction here. It's too abrupt. "I shall be away for some weeks, and as for you, your patients might be encouraged by seeing you more often at your surgery." That shouldn't be the nearly-last thing Jeremy Brett says on-screen. Surely the speech about the blowing east wind of the First World War would be better. This isn't satisfying.

But it also isn't an ending. And that's... rather nice, from the persective of a lifelong fan. "I shall be gone some weeks..." "But what of Baker Street?" "You can carry on without me, and meanwhile I shall be watching you." It's said as lightly as a very drawn Jeremy Brett can make it – and Holmes is gone, off down the stairs with nothing more than an overnight bag. Didn't bother to pack the heavy luggage or even tidy the place up; no need; he'll be back.

And so Jeremy Brett changed the end of Sherlock Holmes' life. Instead of the scene where Holmes and Watson stand on the Sussex Downs, with the sea and the War before them and the Victorian era lost in the mists behind them, this Victorian era does not draw to a close. The only farewell (and it's hardly a farewell) is the moment's hesitation before Holmes turns for the stairs – not a stop, just a pause – and then an hour's worth of proof that Watson and Mycroft can indeed mind the store (mind the universe?) very well until he gets back from the highlands. He won't be long (just a few weeks, he said) and we'll pick up where we left off once he's back.

And because West Wing is an original rather than an adaptation, John Spencer's fate dictates Leo McGarry's. The storyline that the writing staff flirted with and left alone last spring has forced itself upon them. The show they film this summer cannot be the show they were planning. "We have lost a dear, dear brother," Bradley Whitford said in a prepared statement he could hardly manage without tears, and they have also lost wherever they intended the various character arcs to end up at. Josh's story and Bartlet's story and Santos' story – and Leo's story, of course – are all different. Because of John.

And I found myself sitting in bed and mourning the loss of the tale they had planned. Which is what we always mourn, when someone dies suddenly. When death comes abruptly and at a young age, the people left behind find themselves grieving for what could have been (should have been). It wasn't supposed to be this way, we say, and we mean, The story wasn't supposed to end this way. I had a story in my head, and this wasn't it. She was supposed to graduate from college. He was supposed to walk his daughters down the aisle. He was supposed to do intelligence work for the First World War, and he was supposed to be a vice-presidential candidate.

And then we grit our teeth and deal with the story we've got. In the real world, all the time; and now, oddly, in the fictitious worlds we visit.

It never used to be possible, for actors to change characters.

I'm not sure I mind. If we the audience didn't care enough to let the lives of the actors influence the lives of the characters – well, then, we wouldn't be as moved as we are by the results. And what a tribute, too, to Jeremy and to John – to have given form to characters so realistic than no substitute form will do, and who must therefore fade away when their actors are gone.