Come to the Dark Side, we Have Crack!
Voldemort was sitting in his throne like chair, looking over his gathered minions. "Tonight," he said. "We will celebrate the death of the Light's leader, Albus Dumbledore!" The Death Eaters, all in their black robes and white masks, cheered. "I also have a little gift for all of you," he said, and Wormtail, who was waiting for this cue, whipped a cloth off of a table filled with bags of white powder.
"Uh, my Lord, do you really think that this is a good idea? The last time, you did lose your nose, after all," Lucius Malfoy asked.
"Silence! I went through a lot of trouble for this, Lucius, so I suggest you enjoy it," Voldemort threatened. Lucius gulped, and lead his son to the table.
Flashback!
At another Death Eater meeting, Voldemort and his loyal followers were sniffing cocaine.
"Ahhh," Voldemort sighed, before a searing pain penetrated his nostrils. After flailing around for a while, he blacked out.
Later
The Darkest Lord of all time groaned, and opened his eyes to a white room and the pale, tense face of Narcissa Malfoy.
"What happened?" Voldemort asked.
"We-well, my Lord, you, uh, sort of overdosed, and your nose…" she trailed off.
"What?" Voldemort demanded, noticing how his voice seemed very pinched.
"Your nose, well, had to be…cut off," Narcissa said very quietly. "Someone used a Dark curse because it was burning you, and, so…" she handed him a mirror. Voldemort took a long look at his new face,
"Crucio."
"AAAAAHHHHHHHHHH!"
End Flashback
The Death Eaters and their leader were enjoying themselves, under the influence of crack cocaine, when a raven headed, bespectacled face with a lightning scar over his bright green eye.
"Uh, guys, I don't think we have to worry about secrecy," he told his companions. A gangly red head and a bushy haired girl followed him into the room, unheeded by the assembly of their foes that they passed, even when they elbowed them aside.
They walked up to the master of the Dark Side, to find him sprawled out over his ornamental, oversized chair.
"Uh, should we check for a pulse?" the girl asked. The ginger held his fingers to the artery in Voldemort's neck, checking for a heartbeat.
"Nothing. He's dead."
"So, now what?" the black haired individual asked.
The bushy haired girl looked around them at the wasted Death Eaters. "Join the party?" she suggested. Her male companions gave each other grins.
"Alright!" they said, and that is how Harry Potter and his best friends, Ron Weasley and Hermione Granger, symbols of the Light Side after Dumbledore's death, joined the Dark Side. Also how Voldemort died from overdosing, which is how he lost his nose.