This was written in response to a challenge posted on 30minutefics, on livejournal.As you might suspect, it was written in half an hour.
"Challenge #10 (Locked Up): two HP characters are locked in a room of Hogwarts with no apparent way out. One of them is claustrophobic, and the other has to figure out a way to calm them down. Who, what room, and the outcome are up to you!"
"Psst! Bighead Boy!" The third eldest Weasley turned sharply on his heel, looking around suspiciously. It was already long past curfew, and regular students weren't supposed to be out roaming the halls—especially in such dangerous times.
"Who is there?" Percy called out, his voice echoing through the wide hallway. "All students should be in bed! If you don't come out right now and return to your common room, I will be forced—"
But whatever he would be forced to do was never found out, because at that moment a snowball appeared out of the darkness and smacked him squarely in the mouth.
"Show yourself!" Percy yelled immediately, wiping slushy snow from his face. "I am Head Boy, and I will not stand for such treatment!" He heard muffled giggling from behind the suit of armor across the hall, and strode forward to catch the culprit.
"Not there!" someone said cheerfully from a few feet to his left. He looked up to see a Slytherin seventh year girl stepping out from behind a potted plant. She held another snowball in her bare hand, and water dripped between her fingers to splash onto the polished stone floor.
"You!" Percy shouted, advancing to take the culprit back to the Slytherin common room. If they were lucky, they'd run into Filch or Professor Dumbledore on the way, and this girl would get her proper punishment. "Ten points from Slytherin!"
"Only ten?" she giggled, and threw the snowball. It hit Percy in the chest with a soft piff, but before he could react or take any more points away another snowball hit him in the back. The enraged Weasley spun to face this other opponent, face red as his flaming hair.
"A little high—I was aiming for your bum," said the other girl, also a Slytherin seventh year, in a mock disappointed tone. "Ah, well, you don't have much of one anyway!"
Percy opened and closed his mouth a few times and turned back to the first girl, who was running noisily down the hall, laughing out loud. She appeared to be out of snowballs, so Percy ran after her.
"Can't catch me, Weasel-head!" she jeered, and ducked into an open door. Before she could slam it shut in his face, Percy slid into the room. The door clicked shut on the corner of his school robes, but he was too busy staring at his surroundings to notice.
"Are we in a closet?" he whispered, eyes wide. The little room was lit by a single torch burning merrily in its wall bracket, but that one flame was enough to cast light on every wall of the tiny storage closet. Taking up most of the space were old broken desks and a few cardboard boxes. The Slytherin girl had stumbled into one of the desks and fallen to the floor; she got up slowly, wiping her robes free of gray dust balls and sticky pieces of spider webs.
"I didn't know this was here," she said curiously, looking around. "I wonder what's in those boxes?" Ignoring Percy's fear-stricken face, she shifted so she could reach the nearest box and began working it open.
"We're—we're in a closet," Percy repeated, sounding genuinely afraid now. The girl looked up in surprise.
"Is that a particularly bad thing?" she asked dubiously. Percy was white and shaking. He turned suddenly toward the door and began jiggling the handle, trying to get them out. It was locked.
"We're stuck in a closet!" he yelled, stumbling back away from the door. His robes were still stuck and had tangled around his legs; he fell backward and slammed into a desk. It collapsed under his added weight, sending up a fine spray of dust.
"It's no big deal," the Slytherin said, looking uncomfortable. She tried to back away from the terrified Gryffindor, but didn't have space to move.
"No big deal?!" Percy screamed, trying to get to his feet but slipping on all the dust in the room. "No big deal, she says! WE'RE IN A CLOSET!"
By now the Slytherin's friend was outside the door, knocking and trying to communicate through the heavy wood.
"Shut up for a minute," Percy's companion said irritably, shoving him out of the way with her foot so she could put her ear to the door. "I can't hear you!" she yelled to her friend. "Weasel-face is freaking out, just open the door!"
"It's locked!" she heard faintly from the other side.
"So unlock it!"
"I don't have the key, stupid!"
"GET ME OUT OF HERE!" Percy yelled, still jerking maniacally at his robes, but they held fast.
"Oh, for Pete's sake—use the alohomora charm!" the girl in the closet called to her friend.
"You do it, I don't have my wand," came the response.
"Are you shitting me? Neither do I!"
"Get the weasel to do it, then."
"I don't think he's up to much…" The trapped girl turned to look at Percy, who was hyperventilating and still struggling to regain his feet, which were completely tangled in his robes. "Weasley, give me your wand," the Slytherin commanded, holding out her hand.
"Open the door!" he screamed. "I'll do whatever you want, just OPEN THE DOOR!"
Sighing irritably, the girl bent down and reached in the pocket of his robes, where she quickly found his wand.
"Clean as a whistle," she sneered, and pointed it at the door. "Alohomora!"
There was a flash of yellow light and a bang like a toy rocket. The door swung open, its handle completely gone—along with a huge chunk of wood. Whimpering slightly, Percy scooted out of the room, not even bothering to stand up first. The impatient Slytherin outside looked at him in disgust, then turned back to her friend.
"Holy—are you alright?" she asked in shock. The formerly trapped Slytherin stood completely still in the doorway, Percy's wand still in her fingers. She was covered in yellow goo, which dripped off her face and splashed wetly to the floor.
"Oh, yes," Percy said awkwardly, recovered from his claustrophobia, when he saw the state of the girl. "I should perhaps have mentioned… I have a number of protection spells on that wand so no one else will try to use it…"