The book Harry Potter and the Chamber of Secrets contained a significant hint that Harry was a Horcrux, but the film omitted it. This had a lot to do with the subtle nature of the clue and the fact that the now-important passage would have appeared only mildly intriguing when audiences first read it.
Returning to the second Harry Potter book after the series was completed, it becomes clear that Harry felt a strong connection to Tom Riddle’s diary long before he discovered he was a Horcrux himself.
Voldemort’s Horcruxes were first introduced in Harry Potter and the Half-Blood Prince, but Harry first came into contact with one of these objects in Chamber of Secrets when he discovered Tom Riddle’s diary. Initially, Harry was told that the diary contained Voldemort’s “memory,” but his lessons with Dumbledore revealed that it had actually been a Horcrux.
The major plot twist in Harry Potter and the Deathly Hallows was that Harry himself had been a Horcrux. In retrospect, his book’s interaction with the diary made a lot of sense.
The book The Chamber of Secrets revealed a connection between Harry and Tom Riddle.
Though Harry trusted Tom Riddle in the film, his bond with him went far deeper in the novel – even before he learned out how to communicate with him through the diary’s pages. When he initially discovered the journal and discovered it was empty, Ron advised him to simply toss it away.
Something about the blank pages and Tom Riddle’s name, though, gave Harry the impression that he knew the owner. Of course, this couldn’t be true because the date on the journal placed Riddle at Hogwarts 50 years before. Yet, as stated in the novel, the Boy Who Lived couldn’t escape the notion that they were linked:
“Even Harry couldn’t explain why he didn’t just toss Riddle’s journal away. Even though he knew the journal was empty, he kept taking it up and flipping over the pages, as if it were a narrative he wanted to finish. And, while Harry was certain he’d never heard the name T. M. Riddle before, it seemed to mean something to him, almost as if Riddle was a childhood buddy he’d forgotten about. But this was ridiculous. Dudley had made sure he’d never had pals before Hogwarts.”Harry Potter and the Order of the Phoenix
This passage from Chamber of Secrets may have appeared to be a way of drawing readers’ attention to the strange book Harry had just discovered, but when revisited after the conclusion of the Harry Potter series, it’s clear that this was an early hint that Harry and the diary had something in common – they were both Horcruxes.
Harry considered Tom Riddle to be a boyhood buddy since he had grown up closer to Riddle than anyone else. The notion that he and the journal were two aspects of a broader whole perplexed Harry.
Why Did The Chamber Of Secrets Film Downplay Harry Potter’s Relationship To The Diary?
In the novel and film adaptations of The Chamber of Secrets, Harry wrestled with the notion that he was fundamentally wicked. The school assumed he was the Slytherin heir, and for all he knew, he was.
He got much more worried when he found he shared many similarities with Tom Riddle. Dumbledore said in the film that Voldemort gave Harry part of his powers when he tried to kill him, which explains the parallels.
Yet, because the book emphasized Harry’s relationship to Tom Riddle and the diary, it wasn’t as easily explained away.
Because movies can never include all of the material contained in a book, the Chamber of Secrets film was forced to make cutbacks. The intricacies of Harry’s link to Tom Riddle and his journal were primarily revealed in the Harry Potter novel through the boy’s inner conversation.
As a result, translating to the screen was significantly more difficult. Furthermore, these nuances would have looked insignificant at the time the film was developed and released. Years later, it became evident that Harry’s intuition regarding Tom Riddle’s notebook was a hint about the series’ main narrative surprise.