There are many details in Harry Potter that remain unexplained, even by J.K. Rowling herself. This is perhaps why the fan community surrounding the films and books has developed numerous theories to fill in the gaps of the main storyline. It may sound unbelievable, but many theories have found their way to the author’s attention!
Harry Potter Begins
Professor Trelawney once made some “shocking” predictions regarding Harry Potter and his destiny, including a quote about Voldemort: “Neither can live while the other survives.” It became increasingly clear that Harry and Voldemort would eventually have to face off against each other, but the journey leading up to this confrontation was equally thrilling. Some fans have suggested that Voldemort’s demise was foretold, hinting that Harry’s survival is as inevitable as a fateful twist of the plot.

According to the prophecy, Harry could only escape death at the hands of Voldemort. The burden of this prophecy weighed heavily on Harry, as he could not rely on his loved ones—his parents, Dumbledore, or Sirius. Additionally, this prophecy closely tied to Harry’s identity as “the boy who lived.”
Professor Trelawney Knows Harry Potter as the “Chosen One”
The Divination professor at Hogwarts made several accurate predictions, some of which were proven to be wrong later on. She once predicted that Harry Potter was born at the “turn of the tide,” which does not hold true since Harry was born on July 31. However, for many fans, this prediction seemed “right” because another famous wizard, Tom Riddle or Voldemort, was indeed born around the same time. This implies that Trelawney was interpreting Voldemort’s dark presence within Harry, labeling him as the “Chosen One” but not fully grasping the complexity of the situation.

Hermione’s Cat Has Ties to Harry Potter’s Past
Hermione’s cat, Crookshanks, has some truly remarkable moments throughout the series. Crookshanks is incredibly intelligent, able to distinguish between Wormtail and Sirius, and has saved the trio from danger on more than one occasion. This implies that Crookshanks has lived a long life and encountered many people. Consequently, many fans theorize that Crookshanks may have been Lily’s cat, since when the Potter family was attacked by Voldemort, this cat could have vanished (and possibly even been cared for by Sirius).

Neville’s Mistakes with Spells from the Start
As a Gryffindor student, Neville Longbottom struggled significantly with magic. He even had to use his father’s spell book for five years of schooling, which led to some of his most embarrassing moments. Many fans theorize that because of his mistakes with spells, Neville was unable to fully harness his abilities, leading to his timid and introverted nature. It wasn’t until the climactic battle at Hogwarts that Neville finally unleashed his potential, proving he was far more than just “the boy who couldn’t.”

The Dursleys’ Behavior as a Result of Voldemort
Both in the films and the books, the Dursleys are portrayed as having a negative effect on those around them. Anyone who lives near the “Chosen One” tends to become bitter, resentful, and ultimately malicious. This is perhaps why Ron used to argue with Hermione and Harry when they donned Slytherin’s colors. Since Harry Potter is also the “Chosen One,” fans have speculated that the Dursleys’ behavior stems from living with Harry for too long.

Harry Potter, Snape, and Voldemort as Brothers
In the film The Deathly Hallows, viewers were treated to the story of three brothers who each wielded a different Deathly Hallow. The eldest brother had the power of the Elder Wand, the middle brother had the ability to bring back the dead, and the youngest brother was granted a way to escape death.

According to many fans, this story reflects the destinies of the three main characters: Voldemort—the power-hungry elder brother, Snape—the middle brother longing for love, and Harry Potter—the youngest brother destined to face death. Additionally, Dumbledore’s role as a mentor can be seen as akin to the spirit of Death itself. While this may sound far-fetched, it is a theory that J.K. Rowling has acknowledged and appreciated.
Source: Screen Rant