The Stand – the original version of it, something I'll talk about later – was published in 1978. I read it 16 years after that. I can remember the time and place: on holiday in Turkey with my family. I can remember that the copy I had was already falling apart, because it was enormous, and the binding wasn't made to be opened, I don't think. The glue melted as I read the thing; page by page, it fell apart. While I knew I loved King before that holiday, afterwards I'd have followed him to hell and back. It's because of The Stand that I've read all his work, and that I embarked on this series; it's because of The Stand that I'm a writer at all. And because of all this, I don't really know where to start writing about it.

Maybe with Captain Trips. Prior to 1978, King had published three novels under his name that focused on ordinary people ruined or damaged by extraordinary (and inexplicably paranormal) situations. The Stand looked at those ordinary people – the readers of his book – and said: let's damage you all. Rather than the threat being ghosts or vampires, it was a sickness, nicknamed, in the novel, Captain Trips. The sickness was a flu that killed 99.4% of the world's population, and it's terrifying, because we all get the flu. Even as you read the novel, you feel a chill coming over you. (Trust me: I reread this partly on my morning commute, sitting next to somebody with a cough that sounded like death. It's still scary.) Because it's plausible, it affects people in a lasting way. When swine flu broke out in 2009, I lost track of the number of tweets referring to it as Captain Trips. When we're scared we joke; and we joke because of the bubonic plague, because of Spanish flu, and because it feels so wholly reasonable to imagine a virus decimating the world. Worse still? Captain Trips was made in a lab, just like those biological weapons we're all slightly terrified of. The bad guy in The Stand was made by us, and it killed us. That's hubris for you.

I call it the bad guy, but Captain Trips isn't the bad guy. Not really. That honour falls to Randall Flagg. I've mentioned him before – in my Carrie and Night Shift rereads – but here's where he makes his grand entrance. He's a man of many names: The Walking Dude, The Ageless Stranger, He Who Walks Behind The Rows, The Man In Black, Walter O'Dim, The Dark Man. In The Stand, one character calls him The Antagonist, vague and present and inexplicable. He's bigger than the novel, than the world that's collapsed and torn itself apart; and he only appears when it's done, walking from nowhere, only hazily able to remember who he was before (but that he killed policemen, fought for the KKK, and helped to kidnap Patty Hearst).

Where King's previous antagonists were small fry (or protagonists flipped on their heads), Randall Flagg is never less than pure evil. He has a counterpart, as all evils should: Mother Abigail, 108 years old, who communes with God, and who is the frail good to Flagg's evil. Both have the ability to inspire those around them, but Flagg has an advantage: evil is inherently stronger. It's easier. He's able to gather an army from the weak-minded, the stragglers, finding the darkness that's in us all and using it. He brings out everything awful in those susceptible to him: in his lackey Lloyd, and Trashcan Man, and The Kid, and Harold.

Harold. Poor Harold Emery Lauder, the weakest of the weak. A boy only a couple of years older than I was when I read the book for the first time, and who – like me, as I was discovering – wanted nothing more than to be a writer. And he knew about the same things that I did: being in love with girls who didn't know he existed; wanting to be somebody that he was hopelessly ill-prepared to be; and (the bane of all teenagers) feeling singular, alone. Harold was the crux for me; he presented me with the question that makes the novel so powerful and affecting to so many people. What would I do? If I was suddenly completely alone, if I was given the ability to do anything I wanted with no consequences, would I retain my morality? Or would I, like Harold, naturally skew towards evil because of my baser – albeit human – desires? Do we all have that potential inside us?

As the novel progresses and the survivors of the flu are forced to pick sides – drawn through their dreams to the darkness or the light, to Randall Flagg or Mother Abigail – Harold shows his true colours. In the novel's early stages he is a confused, angry, horny teenager; through Flagg's influence, he loses himself. He becomes a killer, a cold-blooded mess of rage when Flagg persuades him (using sexy schoolteacher Nadine, and the promise of Harold finally getting laid) to detonate a bomb and kill his friends. After succeeding and running away, he ends his life alone, his own hands on the gun, the only time in the novel he's actually offered anything resembling control. I remember thinking how terribly sad this was, because when the book starts he's just a kid. That's easy to forget. Stu Redman feels sad for him as well, and if I most associated with Harold at times, Stu was who I wanted to become.

Why? He's noble. He's quiet and moral and even passionate, and he manages to help inspire the gang of good guys to carry on, despite Randall Flagg's dark temptations. He's the one whom Mother Abigail entrusts to go to Flagg and fight back. He's an authority figure, respected and clever, and he's willing to die for the good of the world and his friends. He doesn't: he breaks his leg, almost as if he's spared, and he watches Las Vegas explode at the novel's close; the threat eliminated, the world ready to rebuild itself. He is able to be the father to Frannie's child.

That's not an accident. Nothing in The Stand is an accident. As much as it's a novel about the battle between good and evil, it's also a novel about fate. These people – the American contingent of the 0.6% of the world's population who survived Captain Trips – manage to meet up in Las Vegas, called from all around by dreams. Did they choose to find each other, or was it chosen for them? Mother Abigail's dreams come courtesy of God; she is his prophet, and she assembles her own biblical-type followers. Pregnant Franny, whose child can assert the human race's survival; the forgiving and ailing Glen; deaf-mute Nick; mentally challenged Tom Cullen, who will save Stu Redman; Larry Underwood, who starts the novel dreaming of Flagg, and is filled with darkness, but somehow finds the light. All the cast are put upon and challenged.

I read once that The Stand was essentially the Book of Job, with the survivors in Job's place: tested by good and evil both; pushed and challenged to see how much they could endure, as if their suffering were a game. There's a little more epic fantasy here than in the Bible, maybe, and it ends not with a war, but with an accident; with the chaos of Trashcan Man finding a weapon, and with Flagg's showing off going to far. But I can still see it. Good wins by default, because evil cannot. Those were the rules in the Old Testament, and they're the rules now.

I've read this book five times in adulthood, by my reckoning, and more when I was a teenager. I know some people read books over and over, but I don't; I'm a once-round-then-shelve-it reader, unless a book really stands out to me. This is my most reread book. I can't think of one that has affected me so much. It scared me and excited me; but more than that, it was the first time I noticed the textures of a novel. The Stand is dense and rich. Every character is full and alive, and they're all in the book with a purpose. They cover every shade of human morality, and that astonished me: the deftness of King's writing in making no two feel alike, and making their deaths – because a lot of the cast die, heroes and villains both, something that almost feels inevitable from the outset – mean something. Everything in the book means something, and nothing is accidental. I can still read it and see the narrative threads, set up to be exploited, revealed or knocked down: and the hints in the subtle stylistic touches (Mother Abigail's side drawn into longer, more florid descriptions of their actions; Flagg's side blunter, more bullish, more exposed).

I don't think I can talk objectively, really.

The Stand is a masterpiece, and I don't use that word lightly. King says in the novel's introduction that he "wanted to write a fantasy epic like The Lord of the Rings, only with an American setting", and that's absolutely what he did. I didn't read Tolkien when I was a kid, I read this. These pieces are about me rereading King's work, and with The Stand, there were sections that felt almost as if I could recite them. It made me who I am, I think. It started me thinking that I really wanted to write a novel, not just play with stories. It made me want to practise and work at my writing, and then write drafts of books that wouldn't ever come to anything, and then, after years of turmoil, write a novel that finally got published, called The Testimony. And it wasn't until I was sitting in an editorial meeting about it, and somebody mentioned The Stand that it all fell into place. The Testimony is a novel where everybody in the world hears what might be the voice of God; and then people start falling ill, some awful flu-like symptom destroying them. Some, a small percentage, are immune to God's words, and – it seems – the illness. It's written from the viewpoints of many different characters, all of them showing different shades of humanity, of morality. Things go nuclear. It's nothing like The Stand, when you actually get down to it, but as I sat in that editorial meeting, and as I read The Stand again, I realised that I am wholly, totally indebted to King's book. I couldn't have written The Testimony without wanting to capture some of what The Stand did in me; and so I wouldn't be who I am without having read it, and having had it in my life. I don't think it's King's best novel – there are many more to come that could lay claim to that title – but, to me, it's easily his most important.

Connections

Well. Randall Flagg is King's most persistent antagonist, and the single biggest connection in King's books (bar, maybe, Maine). This is where Flagg really begins, and it's from here that he finds his way into more novels than you can shake a small black stone with a red flaw at. But he's not the only thing. In Wizard and Glass, the fourth book of the Dark Tower series, the main characters travel through an alternate reality version of Topeka post-Captain Trips, complete with graffiti of Mother Abigail and Randall Flagg…

Versions

Important to note, this: there are two versions of The Stand. One was published in 1978, and it's about 800 pages long, and it's set in the 1980s. Another was published in 1991, and it's about 1,200 pages long, and it's set in the 90s. The books are the same story, the same characters; content cut from the early version was put back and the book slightly remastered, as it were, for King's later, more-receptive-to-giant-novels audience. Whichever one you read it's the same book, but for the finality of a single scene at the end of the remaster: where Randall Flagg has survived the novel's endgame, reborn somewhere else entirely, new memories and a new identity, and with a new group of people to try and lead.

Next time

We go no slower than four miles an hour through an alternate-history United States in The Long Walk.