A/N - Mild crack. Using the prompt:
This is the way the world ends
Not with a bang but with Lucius Malfoy's hair.
Regulus crept behind his brother, his hands shaking and his breathing fast.
"Are you sure this is a good idea?" he whispered.
"It's a brilliant idea," Sirius scoffed, not bothering to turn to face his brother.
"But he'll know it was us, or you at least. Won't we get in trouble?" Regulus asked.
"Where's the fun in doing something if no one knows it's you?"
"Because you know it was you!" Regulus hissed. The shaking in his hands had increased, and he was really starting to doubt he'd be able to do this.
"It'll be fine." Sirius finally turned to face him then, just as they reached the closed door. "But you don't have to do this. Not if you don't want to."
"So, what? You'd do it alone?" Regulus asked. "You always said that was boring."
"Well, yeah. But this needs to be done," Sirius said. "If you want to back out, now's the time."
"Alright."
"Alright?"
"Let's do it."
Sirius grinned at his brother, then turned to face the door. He waved his wand, muttering an incantation, and the lock clicked softly open. With a glance over his shoulder, finger pressed to his lips, Sirius led Regulus into the dark room.
.oOo.
He was awoken the next morning by a loud scream; the banging of doors and running footsteps were quick to follow. Sirius was already at the door, looking out into the corridor.
"You!" Narcissa screamed; Regulus couldn't see her, but he was reasonably certain that it was Sirius how had caught her attention. "What the hell did you do to him?" Sirius only laughed, somehow managing to sound both evil and childlike.
Regulus pushed aside his duvet, lowering his feet to the cold floor and slowly making his way over to his brother.
"Where'd Narcissa go?" Regulus asked, when he could see into the corridor.
"Probably back to comforting Malfoy," Sirius said with a smirk. "He's gonna need it."
"Have you seen him yet?"
"Nah. 's what I'm waiting for."
"How bad d'you think it'll be?" Regulus asked, leaning back on the opposite side of the door frame to his brother.
"Judging by all the screaming? Sounds bad," Sirius said. "Haven't figured out if it was Malfoy or Narcissa, though."
"You!" Sirius rolled his eyes at their mother's words; apparently Narcissa had been taking lessons. "How could you do- And to- You could have ruined your cousin's wedding!"
"Based on-" Sirius began.
"That's enough!" Walburga screamed. "Your father will be hearing about this!"
.oOo.
"Boys," Orion said, looking from one to the other. He took a deep breath, the corners of his mouth twitching up slightly. "In the future, please leave Mister Malfoy's hair alone."