Stories, much like life, are determined by decisions. Lord Voldemort decided to murder Harry Potter’s parents. Albus Dumbledore decided to place him, as a baby, in the safety of the Dursleys; the Dursleys decided to treat Harry like dirt. And so on. Decisions are the paths we choose from all the other paths.

Hence our fascination with paths untravelled – the decisions we didn’t make, and what would have happened if we had chosen differently. In quantum mechanics, this is known as the many-worlds interpretation: the theory that every decision is in fact a branch point, and all alternative decisions are being played out on different branches, in other realities.

The major branching point for the Harry Potter series, of course, is its first book, Harry Potter and the Philosopher’s Stone. But what of the magical paths untravelled? What decisions would have altered the series as we know it? Let’s find out…

What if Harry Potter hadn’t grown up in the Muggle world?

Right from the very first chapter of Philosopher’s Stone, a major decision was made: Albus Dumbledore decided to leave Harry Potter with his Muggle relatives, the Dursleys, in the hope that he would have a normal upbringing.

But what if Dumbledore had decided otherwise? What if Harry didn’t need to be where his mother’s blood was, and had been raised in the magical world instead? Well, for one thing, it’s safe to assume that the humble, modest and bewildered Harry Potter we know from the books wouldn’t exist. He would arrive at Hogwarts with a fully-formed knowledge of magic and his own fame. Would he have been a Gilderoy Lockhart in the making? Or maybe, after having been asked for the thousandth time for a magical selfie (‘Can you lift your hair up so we can see the scar?’), he would have grown tired of fame. Either way, it’s doubtful that upbringing would have forged the fortitude needed to fight Lord Voldemort. His childhood with the Dursleys wasn’t a happy one, but it did at least make him who he was.

What if Harry had not met Ron on platform nine and three-quarters?

Not everything is decided directly, of course. Some things are decided by chance. Take Harry bumping into Ron Weasley on platform nine and three-quarters, which is how he was able to get through the magical barrier. What would have happened if chance had other ideas?

Well, for one, Harry probably would have struggled to catch the Hogwarts Express. But let’s just assume that he was smart enough to figure that one out for himself. For there are bigger ramifications at play here. If Harry had not met Ron at King’s Cross Station then they would not have sat together on the Hogwarts Express, they would never have bonded over sweets, and Ron would never have taken out his wand and caught the attention of Hermione Granger, one of the most important figures in the Harry Potter series.

Would the events of the Harry Potter series have unfolded without the friendship of Ron? What if, for example, he had found Neville Longbottom, or Draco Malfoy? Would any of them have aided in the search for the Philosopher’s Stone, or been able to win a gigantic game of wizard chess?

What if Harry was sorted into Slytherin?

This is a big one: the moment the Harry Potter series could have branched out in either one of two ways. If Harry had been placed in Slytherin, it would have altered his path drastically. It’s doubtful, for example, that he would have developed such a strong friendship with Ron and Hermione. Although that’s not to say that he would have got on with Draco Malfoy, either. He was, after all, the worst.

Not having the support of Ron and Hermione also casts doubts on Harry’s ability to solve the series’ big mysteries. Maybe there would have been a super-smart, heroic Slytherin friend to help him? Or maybe he would have just failed to find the Philosopher’s Stone and thus, inadvertently, returned the wizarding world to darkness four years early? Even if that did happen, would Harry have been able to pull Gryffindor’s sword out of the Sorting Hat in Harry Potter and the Chamber of Secrets?

What if Ron had not been mean to Hermione?

This is one of those things that may seem insignificant but is actually very important. Early on in the book Harry and Ron are already friends, but were yet to bond with the super-smart but pompous Hermione. In fact, after showing off in Charms, Ron was particularly nasty to her: ‘It’s no wonder no one can stand her,’ he said. ‘She’s a nightmare, honestly.’ Hermione, having overheard this, fled in tears.

Now, of course, there’s a chance that Harry, Ron and Hermione would have bonded in a different way, but as it stands, it was Ron’s mean jibe that sent Hermione running to the girls’ toilets, which sent her on a collision course with a troll, which sent Harry and Ron on a mission to rescue Hermione from said troll. You can’t get a stronger bonding exercise than that.

So why are these chain of events so important? Because as we mentioned earlier, Hermione is one of the most important figures of the series: a genius vital to the mysteries the trio must solve year after year. Just take Philosopher’s Stone, where Hermione finds the book that unlocks the mystery of Nicolas Flamel. Or beyond that, where she solves the mystery of Chamber of Secrets while unconscious, or saves the day with a Time-Turner in Prisoner of Azkaban. The list is long.

If the trio hadn’t bonded over that troll, and Harry and Ron hadn’t become close friends with Hermione, it’s safe to bet that the Harry Potter series would have consisted of Harry and Ron just bumbling about, never solving anything. Voldemort’s victory would have been swift, and easy.