Before we dive into what could have happened, let’s look at why the diary was so significant in the first place…
When we initially come across Tom Riddle’s diary in Chamber of Secrets, we are unaware of just how powerful an object it truly is. At first the diary bought from a Muggle stationary shop seems harmless. The pages are blank after all… but we soon learn there is more to this journal than meets the eye.
Soon we are taken into the diary and shown the memories of Tom Riddle. The diary wants us to believe it was Hagrid who had opened the Chamber of Secrets and Tom who had stopped him. Of course, at this point we were still unaware that Tom was Voldemort. However, when Ginny is taken to the Chamber and Harry goes to rescue her, we soon realise that this is a rather insidious artefact, and that this sentiment applies to its original owner too.
It was Tom Riddle who had found the Chamber of Secrets during his time at Hogwarts, and it was he who opened it – which led to the death of a student. Having been worried that Hogwarts would be closed because of this murder, Tom pinned the blame on someone else and abandoned his current plan to finish Salazar Slytherin’s work. Instead, he left an enchanted diary which would complete the mission in the future by possessing and manipulating an innocent soul, such as Ginny, to do his dirty work.
If it wasn’t for Harry’s timely intervention, Ginny would have died, and Hogwarts would have closed. When Harry destroyed the diary, he wasn’t just getting rid of an awful object but was also destroying a part of Voldemort’s soul – as the diary turned out to be a Horcrux.
Yet none of this may have happened if Lucius Malfoy hadn’t slipped the diary into Ginny’s book in the first place. While the Chamber of Secrets remaining sealed would have been a good thing… we can’t help but wonder what impact it would have had on the rest of the story. Would it have changed Ginny? Would it have had an impact on her relationship with Harry? Most importantly, what would it mean for the destruction of Voldemort?
When Tom Riddle created the Horcrux out of his diary, he probably didn’t have an exact idea of when it would be used to open the Chamber of Secrets again. In fact, it wasn’t his decision to open it at all. That was all down to Lucius Malfoy and his vindictive desire to get one over on Arthur Weasley. We think it is pretty safe to say that there is a fair chance that the Chamber would have remained closed in Harry’s second year at Hogwarts. We also reckon that could have extended to Harry’s entire time at school. We highly doubt that there was any pupil at Hogwarts who would have had the capability to open the Chamber, even if they did have strong anti Muggle-born views (like Draco Malfoy for instance). So, without the diary we reckon it might have stayed shut.
We also think that the Chamber may not have been opened if the diary had come into the possession of someone who wasn’t as vulnerable as Ginny. For Tom Riddle's plan to work, he required an innocent soul who needed a friend. They had to pour themselves into the diary and be completely open. If they were guarded, he might not have been able to possess them and force them to carry out his plan. He also needed someone who would be too frightened to own up to what was happening or ask for help. Ultimately, the person who owned the diary could not suspect its true motives. While we don’t deny that there could have been other students who were susceptible, at that moment, Ginny was the perfect target.
Nevertheless, we’re not saying that it could never have been opened at another moment in time. Lucius Malfoy didn’t seem to understand just how valuable the diary actually was to Voldemort or that it contained a piece of his soul. He just thought it was an excellent way to get rid of Muggle-borns. So, even though he was supposed to take care of it, we imagine he wouldn’t have been able to pass up on an opportunity to try and have the Chamber of Secrets opened again. He might not have chosen Ginny, but he still would have given it a go in the years before Voldemort returned to power.
The sword of Gryffindor was integral to the plot of the Chamber of Secrets – it was what killed the Basilisk. And as the sword is Goblin-made, it was built to imbibe only that which makes it stronger. Therefore, when the sword was used to kill the King of Serpents, it became impregnated with its venom. Now this made the sword an invaluable object as Basilisk venom is one of the very few substances that can obliterate a Horcrux. Without it, the sword would not have been powerful enough to destroy one. If Ginny hadn’t opened the Chamber of Secrets, Harry would probably have been oblivious to the sword, and it would not have been as important.
It was not just the hunt for Horcruxes that made this sword so special, it was also because of what it symbolised. If Harry hadn’t known about it, he may never have had the reassurance that he belonged in Gryffindor. It was the discussion he had with Dumbledore, after he returned from the Chamber (with the sword), that led him to realise that it is our choices rather than our abilities that make us who we are. Without it, his worries about his Slytherin traits would probably have become worse and made life even more difficult for him.
Ultimately, we reckon that the sword of Gryffindor would not have been an important element in the stories if Ginny didn’t have the diary. Harry would probably not have encountered it. Even if he had come across it, it would not have been a crucial tool in the Horcrux hunt but a rather beautiful, if decorative, object.
We’ve briefly touched upon the importance of the sword of Gryffindor as a means to destroy Horcruxes and with that in mind, the short answer would be yes.
If Ginny didn’t have the diary, the subsequent events would not have occurred, and this would have left our trio with no means of getting rid of the Horcruxes. While we know there are other ways of disposing of one, it requires magic that is very powerful and often unstable. Fiendfyre is one example of this. Though, as we saw with the death of Crabbe, it was incredibly dangerous and almost uncontrollable – even Hermione didn’t think she had the skill to handle it. We also think that even if the trio had been able to discover another method for destroying Horcruxes, it would have taken them a long time to figure it out and even if Voldemort wasn’t victorious, he would have remained powerful for a much longer period of time.
It is also possible that Voldemort may never have been destroyed. Without the discovery of the diary, Dumbledore and Harry may never have known about the piece of Voldemort’s soul concealed in it. As someone who hated everything to do with Muggles, it seemed like an odd choice of Horcrux for him. It certainly went against his regular pattern of wanting to use objects that almost seemed like trophies – such as Slytherin’s Locket or Ravenclaw’s Diadem.
Similarly, if Lucius Malfoy had held onto it for a couple more years, the diary would have been back in Voldemort’s grasp and much harder to access. We doubt that Voldemort would have let something so important out of his sight once he knew that his Horcruxes were under threat. We also don’t know if Harry, Ron and Hermione would have been able to get close enough to take it from his possession.
This is an interesting question. There is no doubt that Ginny came away from her experience with the diary and the Chamber of Secrets as a more resilient and wiser person. It was Ginny who was incredulous in Half-Blood Prince, when she found out that Harry had been taking orders from something someone wrote in a book. She knew just how dangerous it could be because of her experience and was a lot warier and a lot less naïve when it came to objects of unknown origin.
Furthermore, the aftermath of this event probably forced Ginny to develop quite a tough skin. As we learn in Cursed Child, Ginny was shunned by her peers for a long time and probably felt quite isolated. But rather than letting that incident crush her, she remained confident and put on a cheery face – even though she still carried the weight of that horrific ordeal.
Yet, we reckon Ginny would still have been as fierce and as strong even if she hadn’t had been through any of that. This was the witch who had been breaking into the Weasley’s broom shed since the age of six and taking each of her brothers’ brooms in turn to practice. She was also determined to be in the thick of things – whether that was as a member of Dumbledore’s Army, fighting underage in the Battle of Hogwarts or her schemes with Fred and George. Ginny Weasley had always been a strong and capable witch. While this incident may have influenced her personality – it didn’t change who she was.
We are pretty certain that Harry and Ginny would have still become a couple. Even if the Chamber of Secrets had not been opened, they still would have been very involved in each other’s lives. She was the sister of his best friend. She was also a fellow Gryffindor. They were both members of Dumbledore’s Army. They both played for the Gryffindor Quidditch team. Their similarities were still there, and we reckon the attraction would have still grown.
It’s also worth remembering that it wasn’t Harry rescuing Ginny that sparked her crush on him – she was already smitten. She was the one who (probably) sent him a Valentine’s Day card before the events of the Chamber of Secrets, and she had always been flustered and giddy in his presence. Harry saving her may have reinforced those feelings, but they certainly didn’t cause them.
That’s not to say that the diary didn’t have any impact on their relationship. When Ginny was being shunned, it was Harry that reached out to her in the Gryffindor common room and asked her to play a game of Exploding Snap. Even as an adult she recalls how important that gesture was to her – and how it made her feel loved.
Overall, we think Harry and Ginny would have still been together. They had such similar interests, and their temperaments were well suited. They both were excellent at supporting one another and knowing what each other needed. They handled decisions maturely – like their temporary break up when Harry went to hunt Horcruxes. So, we reckon that even without that awful shared experience, they still would have had many more moments where they would have got to know each other.