Fluffy the three-headed dog didn't make any appearances after the first Harry Potter installment, but author J.K. Rowling revealed details regarding his fate. Despite his brief stint in Harry Potter and the Sorcerer's Stone, Fluffy became one of the most popular mystical creatures to come out of the franchise. Like fellow dog Fang, Fluffy was also originally owned by Hogwarts groundskeeper Rubeus Hagrid before embarking on a special job.
Before Harry Potter, Ron Weasley, and Hermione Granger joined Hogwarts, Hagrid acquired the three-headed beast from someone at the Leaky Cauldron. Rather than keep him as a pet, Hagrid loaned the enormous animal to headmaster Albus Dumbledore. Fluffy was then used to guard the trapdoor leading to the underground chamber holding the Sorcerer's Stone. Harry, Ron, and Hermione first encountered Fluffy when the trio found themselves in a restricted area of the school after running from Argus Filch. The trio later learned the vicious guard dog could be forced to fall asleep if music was played.
Upon believing Severus Snape was after the magical stone, Harry and his friends sought out its location, meaning they had to get beyond Fluffy. When arriving by Harry's invisibility cloak, the group discovered that the three-headed dog was fast asleep thanks in part to an enchanted harp left by a recent visitor. In order to get to the trapdoor leading to the underground chamber, Fluffy's gigantic paw had to be moved. In doing so, he woke up, leading in the kids jumping to safety. In the book version, Harry used a flute given him by Hagrid to put the dog back to sleep. The Harry Potter franchise didn't provide much insight into Fluffy's fate after the Sorcerer's Stone debacle, but thankfully, Rowling clued in fans.
According to the author, Hagrid set Fluffy free in the Forbidden Forest after the events of the first installment. Considering the stone had been destroyed, the dog's duties were no longer needed. Being the gentle giant that he was, Hagrid must have thought it was best to allow the large animal to live freely among other mystical species. In 2015, Rowling took to Twitter to confirm Fluffy was sent back to his native Greece, which was set up by Dumbledore. Not wanting Hagrid's known dangerous creatures lurking around in the proximity of students and staff, he thought it was best to send the three-headed dog back home.
The Greek aspect of Fluffy's background was fitting for his Harry Potter arc, considering the creature was based on hellhounds from Greek mythology. Hades' hellhound, Cerberus, was thought to have three heads as he guarded the Underworld. The fact that the appearance was incorporated into the creature sent to guard an important chamber was completely intentional. Amusingly, Fluffy's story was seemingly given a recent update, connecting the dog to a taco truck attack. The security footage (via Twitter) showing a "ravenous three-headed dog" believed to be Fluffy was promoted through the social media accounts of the official Harry Potter mobile game, Wizards Unite, in 2019. More than anything, the update confirmed Fluffy is alive and well in the wizarding world.
