"Troll! In the dungeons! Troll!"
Quirrell collapsed in a dead faint, and all hell broke loose.
Harry was unable to keep eating as students screamed and bolted to their feet, upending goblets of pumpkin juice and dropping cutlery with a clatter. It took several loud cracks from Dumbledore's wand to quieten the Great Hall and Harry made a mental note to learn the spell if he ended up having to lead the DA again.
"Quiet!" Dumbledore called. "Please remain calm. Prefects, you will escort your houses to your common rooms immediately. You have nothing to fear from the troll if your listen to instructions. Remain calm and make your way to your common room in an orderly fashion."
Harry swore under his breath and glared up at the staff table. He saw Professor McGonagall talking urgently to the headmaster, but was surprised to see Snape practically seething, staring at Dumbledore with barely disguised bewilderment. Harry suddenly realised the Slytherin common room was in the dungeons, where Quarrel had just told them the troll was. It didn't make any difference that it was actually on the first floor, somewhere suspiciously close to the girls' bathroom.
He grabbed Hermione's robes as she began to stand up and gently pulled her back down onto the bench.
"Harry, come on, we've got to go to-"
"Dumbledore's about to make another announcement."
Sure enough, the bearded wizard let out another firecracker-like noise to get everybody's attention.
"It seems irresponsible to send everybody out throughout the castle when all students are already here, safe, in the castle." He said, inclining his head slightly towards McGonagall. "Please sit back down at your house tables, and prefects, liase with your head of house to ensure that nobody is missing."
Harry glanced up and down the Gryffindor table, trying to see if there was anybody noticeably missing. He had run after Hermione after Ron was an insensitive prat - he hadn't managed to avoid that, but the ferocious glare he had given the other boy before he left had at least prompted him to apologise in their next lesson, which Harry thought was progress - so he knew at least she wasn't going to be squished by a troll, but Harry wasn't convinced that the castle would find a way to endanger somebody else in her place. Hermione had been quiet all afternoon, but Harry had stuck with her, proving she did have friends whilst at the same time subtly telling her to let other people learn, and that if she calmed down a little bit the other children would find her less intimidating and annoying. All of the first years were present, as well as the second and third years and all the Weasleys, but Harry didn't know enough of the older students to be able to do a mental register. The prefects were walking down the table, and none of them seemed too stressed or panicked, nor did anyone from the other houses. Snape, Sprout and Flitwick had left the staff table to see to their houses, and McGonagall stopped behind Harry as he went back to his jacket potato.
"Mr. Potter." She said quietly, but Harry could see how angry she looked, behind the concern for the school. "Is there anything you want to tell me?"
Harry frowned. "No, professor."
"You have absolutely no information about this troll, or how it entered the school?"
"No Professor!"
"This is your final chance."
The other first years around Harry were staring at him in shock.
"I would never put people in danger, professor." Harry said seriously. "Particularly tonight."
Her eyes softened slightly. "Alright." She gave him one last searching look before hurrying over to the prefects.
"What was that about?" Ron asked.
"I was asking her questions about emergency procedures and what would happen if a magical creature got into the school after our first flying lesson the other week." Harry replied. "I can understand why that makes me look guilty."
The other first years accepted this and excitedly began coming up with theories about how a troll would get into the dungeons, and Harry watched as Madam Pomfrey revived Quirrell and checked him over.
Despite a tension in the air, and theories and worries flowing around the Great Hall, the Halloween feast continued; spilled food and drink had been vanished, Snape, Dumbledore, Hagrid and Professor Kettleburn having left, presumably to hunt down the troll, and all students had been accounted for, other than two older Slytherin boys Harry didn't know who had been found in an empty classroom on the first floor and escorted back to the Great Hall by Filch, all 3 with burning red faces.
Harry watched Professor Quirrell insist he should go and help search for the troll, be promptly shut down by Madam Pomfrey, and as a result sit and seethe up at the high table.
The ghosts were drifting around, gliding up and down the spaces between the tables, and Harry thought that combined with the ginormous pumpkins and the bats flying around the rafters it rather added to the atmosphere of a Halloween feast. As the last crumbs and remnants of dessert vanished from the golden plates throughout the Hall, Harry got Nearly-headless Nick's attention as he floated past.
"Sir Nicholas! I wanted to wish you a happy Deathday." Nick's expression changed from polite curiosity to excited surprise as Harry spoke. "I don't know enough about ghostly customs to know if a troll breaking in to the castle is considered a good thing or bad, but it has certainly made tonight memorable."
"Why thank you very much Mr. Potter, and that it has!" replied Nick. "However did you know that tonight was the four-hundred and ninety-ninth anniversary of my death?"
Harry smiled. "Well, I make it a point to know the death days of important ghosts in this castle."
"You flatter me." said Nick, shaking his head so that it wobbled on his neck. "But my condolences too. I know this day is important to you as well."
"Thank you."
Nick drifted off, and the other first years stared at Harry. Before any of them could speak, Dumbledore stood up and the Great Hall fell silent.
"I hope you have all enjoyed the feast, despite the excitement of the night." He said. "You will all be pleased to know that the troll has been found and removed from the castle, but please be advised that the staircase down to dungeon 4 will be out of bounds until further notice for repairs. Prefects, please lead your houses back to your common rooms."
There was a loud scraping of benches as everybody stood, followed by a scramble to fit through the single door. Harry followed after the other Gryffindors, everybody discussing how a troll could have gotten into the castle or how much trifle they had eaten at the feast.