The Game
Things were... calm, at Hogwarts. The reason? Well, let's start at the beginning.
Astronomy tower, during the pyjama party
"The Gryffindor common room paintings are superior though. They basically do our History of Magic homework for us." Ron said around a mouthful of food. Harry nodded in agreement.
"You are so lame, Ronald. Slytherin common room wins, we literally have a view of the black lake." Daphne said, taking a delicate bite of treacle tart. Harry had to marvel at her. For someone with such witty comebacks, she wasn't half posh.
"So? Gryffindor tower overlooks the forbidden forest." Harry grinned triumphantly.
"We see literal Mermaids. We've seen the Giant Squid, close up! He even waves at us!"
"Trying to study here." Hermione muttered, nudging Daphne, not looking up from her book.
"Whatever. Beat that, Potter." Daphne smirked, looking annoyingly smug.
"Okay." Harry said, leaning forwards and grinning. "If we look out of the farthest window to the left in our common room, we can see the quidditch pitch. Luckily for us, my little brother in all but blood Colin has a pair of binoculars. Not just any binoculars, mind. Magic binoculars. We can literally spy on the other quidditch teams, with no effort whatsoever." Harry cackled at the looks of sheer horror on Daphne and Draco's face. "We win."
"POT-"
"Will you all be quiet!" Hermione exclaimed, slamming her book closed. "Why can't you fight in silence, just once?" Harry's eyes lit up, and she groaned.
"Excellent idea Hermione, have 50 people points. Okay, so just like Hermione says, this is now a silent battle. Once you talk, you're out. The last man, woman, or person standing wins, and their common room is crowned best common room ever."
"Bit unfair of you to not give Hufflepuff a chance!" Susan called from across the room.
"And us Ravenclaws!" Terry Boot added.
"Okay, okay, cool cool cool cool cool cool. This class is our entire year group, yes? So, how about we make this official? Hermione?" Harry turned to her, puppy dog eyes in full effect.
"Absolutely no wa- okay, fine." Hermione murmured a spell, and everyone's hair colour changed. "Your hair colours match your house. Green, Red, Yellow or Blue depending. In a second I will cast another spell that will be triggered when you speak."
"I need an exception for tomorrow morning, I have an important announcement to make." Harry claimed.
"Okay, I'll put the spell on you after breakfast. I won't be participating as I'm the caster, so I'll be judge in case of any conflicts."
"Cool. Everyone ready?"
"Yes."
"Do it Hermione."
Professor Sinistra watched the fourth years with a look of complete and utter delight. Snape and McGonagall were going to have a field day! And she might lose her job for letting it happen, but it was so worth it.
~~~~
6 days after the pyjama party
"I can't take it anymore!" Flitwick sobbed. "I can't keep teaching a class of silent students! They all just sit and write and do as their told! No one asks any questions anymore!"
"I know, it's wonderful. I wish the rest of the school would join this silly little competition. It's the best idea Potter has ever had."
"Hush, Severus, just because you hate the students it doesn't mean we all do. There, there, it's okay Filius dear, all the other year groups still speak." Pomona said gently.
"On the bright side." Minerva said. "They are all getting amazingly good at nonverbal spell casting. We usually wouldn't teach them until sixth year. Granger wasn't joining in to begin with, but she got jealous so Ginny Weasley cast the spell on her so she could participate and remain top of the class." Minerva said fondly.
"I'm impressed they've lasted this long." Pomona said. "Not a single one of them has spoken yet."
Aurora frowned slightly "I wonder what will happen when they do?"
They didn't have to wait long to find out. The next day, during lunch, there was a loud BANG, followed by a huge cloud of red and gold smoke.
"Sorry!" Neville squeaked. "I forgot!"
"Oh, Neville." Ginny said, waving smoke out of her face. "Well, Harry put me in charge of the point system until he can speak again, so I'm afraid I have to take 20 people points away from you. And 5 away from Professor Snape as well."
"What did Snape do?" George asked her.
"Nothing, But Harry said every time I give or take points from someone, Snape loses 5 points too. Oh, and every time Snape loses 5 points, I have to take 50 off of the Headmaster." She looked up at the teacher's table, where Dumbledore looked unbothered and Snape was glaring.
"Sorry." She added, not looking at all sorry. Neville, hair now back to its usual colour, returned to his breakfast.
After Neville, the other fourth years slowly began to drop out of the competition, either intentionally giving up or accidentally speaking. Ernie Macmillan's downfall was next, and his was rather spectacular: he tried to ask one of the Beauxbatons students to Hogsmeade with him and a ton of yellow and white glitter spilled from his mouth. By the time the nearest prefect had worked out a counter spell, the corridor was flooded with glitter.
4 days later and the competition was still going, but barely.
"Whose left aside from Harry?" Ron asked Hermione around a mouthful of toast. He had lost when Snape threatened to take 300 points from Gryffindor if he did not answer a question verbally. Upon answering, the classroom was filled with red and gold feathers, which wiped the smug smirk right off of Snape's face. It was a shame, as none of the points would have been removed from Gryffindor anyway thanks to Sirius and Harry.
The teachers and other students had begun trying to get fourth years from other houses to speak, and people were placing bets. Everyone including Snape, who hated the entire thing, was invested.
"Daphne, Blaise, Hannah, Terry, Padma and Harry." Hermione replied, having lost her place in the competition after Draco stole her special edition copy of Hogwarts: A History. All of her clothes turned bright scarlet and gold, but it faded out after a few days.
"Not Terry or Blaise." Ron smiled in amusement as there was a sudden commotion. A blue cloud had appeared over Terry's head and he was doused with rain until he was drenched, and Blaise was surrounded by little green and silver bats.
"Ladies and Gentlemen, People and Dungeon Bats!" Ginny grinned wickedly at Snape, who scowled. "We are down to the final four! One student from each house remains. Place your final bets with my brothers Fred and George Weasley now!"
For the next three days, tensions were extremely high. Hannah had taken to hiding in her dorm, petrified of losing, and Padma was spending more and more time in the library alone.
Daphne and Harry, however, continued as normal. They would laugh silently, throw parchment notes at each other in lessons and hex each other non-verbally in the corridors just like they always did.
Padma broke first. Blue and Bronze un-poppable bubbles followed her around for the next hour. Hannah snapped a few minutes later, a flurry of yellow birds knocking her off balance and almost causing her to fall.
Then there were two.
Slytherins had taken to guarding Daphne at all times, not wanting to risk any foul play from the other houses. Gryffindors tried to guard Harry but failed, because he would just use his invisibility cloak to slip away. Or hiss at people in parseltongue to scare them off, which apparently didn't count as speaking.
At long last, exactly 2 weeks since the beginning of the competition and one week before the first task, the game ended.
Harry snuck up behind Daphne under his invisibility cloak. She was sat at the Slytherin table with Draco. Slowly, ever so slowly, he reached out...
And jabbed her in the back of her head with his finger.
"Ow!" She screeched, and immediately green and silver fireworks went off, the bangs loud enough to drown out the groans and sounds of annoyance from the Slytherins. Daphne herself looked furious.
"YES! GRYFFINDOR WINS!" Harry yelled triumphantly, and instantly red and gold fireworks joined the green and silver ones.
"Wait..." Harry trailed off.
At the Ravenclaw table, Lisa Turpin got to her feet, raised her wand, and waved it. Her hair went from its usual blonde to blue.
"What the-"
"We put a glamour on her hair to trick everyone into thinking she was out," Padma said, large grin on her face. "so I think you'll find Ravenclaw win the title of best common room ever!"
"RAVENCLAW WINS!" Ginny yelled. "Ravenclaw common room is hereby crowned best common room ever!"
"WOOHOO!" The Ravenclaws cheered, and Harry and Daphne looked at each other in pure shock and disappointment before running out of the hall together.
They would be found three hours later by Cedric, Draco, Ron and Hermione - sat on the floor in the kitchens snuggled into each other and wrapped in a huge blanket, their cheeks wet with tears, eating ice cream directly from the tub and a concerned Dobby hovering nearby with a box of tissues.
Oh, and Harry admitted he was lying about the binoculars and being able to spy on the quidditch teams. He spent two days with neon green hair and extremely large ears courtesy of Daphne and Draco.