Ducking into the back room of Weasleys Wizard Wheezes, Harry made sure there was no one around before turning his full attention on the curious twins.
"What is it-"
"-our young benefactor needs?"
Harry leaned closer, and they automatically leaned in as well, sensing that whatever Harry was going to ask them for, it would be big.
"I need you to experiment with howlers and see if something would work…"
Exchanging a glance, Fred and George burst into wide grins.
"Knew you had it in you, Harrikins," one said, slapping him on the back while the other twin wiped a tear from his eye.
"We've raised him so well," he said dramatically, throwing his arms around his twin.
"I know, Gred – finally one who takes after us! We've been waiting for this moment for years!"
Harry cleared his throat. "Actually, it's not for a prank…" The heartbroken looks the twins turned on him made him hesitate. "Well, I suppose it could be taken as such…"
"Oh, Harrikins!" The young student was buried in a massive embrace with a strangled "urk".
OoOoO
A year later, Harry Potter took a big breath, clutching the frail item in his hand as he faced the other students of Hogwarts. The forces of Voldemort were massed outside the Hogwarts wards, and it was time to make a stand.
"Ready?" he asked, and a roar of confirmation came back from the gathering. Taking another deep breath, Harry nodded. "Go."
As one all the students turned to the tables they sat at, scribbling furiously on the papers before them. Harry himself took a long look at the other fighters before bending his head to his own sheet of parchment, channeling all his hatred through the blood quill as he wrote down a spell and addressed it to his nemesis. His howler was the first to fly out of the Great Hall towards the army massed outside the wards – but not the last.
Nobody was surprised, later, to find most of the army dead. Cutting curses were remarkably effective at close range, and some Death Eaters were unrecognizable from the number of howlers they'd received.
A/N: Also, no Horcruxes in this oneshot! I don't see why howlers couldn't be made to shoot spells if you added some of your magic to them (which is why they're using blood quills), since they speak with the writer's voice and everything. Imagine Voldemort's disdainfully amused face when a howler flies up to him. "It seems someone is displeased with the current state of events," he remarks dryly and gets his last answering round of laughter before the howler unfurls and ends his life. It's actually a terrifying weapon, when you think about it.