When Fluffy Got Loose
Chapter 1: School's out
After the Sorcerer's Stone was destroyed, after the year end feast and after Gryffindor won the house cup, the students went home for summer break. The Hogwarts staff members all decided to go on vacation for the summer too. The only person left on the premises was Hagrid because he had to make sure Hogwarts stayed safe. But before the staff left, someone forgot something.
Each morning Hagrid would get up and walk around Hogwarts to make sure everything was okay. He also watered the grass and plants too. But even Hagrid forgot something too. After Hagrid's work was done he was free to do as he pleased. Sometimes he would go out and play poker with the other wizard guys but many times he just sat at home and relaxed. "Never know when sum'em mi' go wrong" he'd always say. But with all the time Hagrid stayed at Hogwarts he never checked the third floor corridor. He never even thought about that part of the building.
While Harry Potter was being tortured by the Dursleys, Ron was spending time at the Burrow with his large family, Hermione was home reading, the Hogwarts staff was on vacation and Hagrid relaxed, there was a problem. Upstairs in the third floor corridor of Hogwarts was Fluffy the three headed dog that used to guard the Sorcerer's Stone. He was left up there all alone. Everyone must have forgotten he existed.