Parasite

Darkness seeped into the world as thick rain clouds gathered overhead while the Hogwarts Express continued on its way north. The occasional droplets turned into sheets of rain battering against the roof and the sides of the train, a veritable torrent of water falling from the heavens. Oleandra could barely make out the sound of the train's wheels clacking as they rolled over the joints in the tracks over the hammering of the rain and the howling of the wind.

The Hogwarts Express's lanterns lit up by themselves, casting their dim lights and staving off the darkness inside and outside the train. There wasn't much to see outside, in any case. In their compartment, Daphne had lit up her wand to read a book, while Tracey had peacefully fallen asleep. Astoria hadn't returned yet.

"It feels like we're slowing down," said Daphne, putting down her book. "But we're nowhere near Hogsmeade yet."

"Maybe a tree's fallen down on the tracks?" Oleandra guessed.

Just as soon as she had said those words, the train screeched to an abrupt stop. The momentum carried Oleandra forward, throwing her out of her seat and into Tracey's lap.

"Are we there yet?" Tracey asked, rubbing the sleep out of her eyes.

The lamps' lights suddenly sputtered and winked out, plunging the train into darkness. Oleandra heard cries of confusion from the neighbouring compartments. 

"Lumos," whispered Oleandra.

To her horror, the first thing she saw was their compartment's door slowly sliding open. A phantasmal being glided through the opening. It was wearing a raggedy, black hood that covered its entire body, save for its skeletal hands.

"Stay away!" warned Oleandra. Seeing as the being was still slowly approaching her, she struck! "Thursaz!"

The attack phased through the creature, harmlessly blasting a hole through the side of the train. Oleandra felt a chill run down her back. Her breath condensed into vapour before her eyes, and frost began to cover every surface in the compartment.

"D,Dementor!" cried Daphne. "Someone, help!"

Ginny gritted her teeth. This had been one of Voldemort's few abject failures. He had never managed to cast the Patronus Charm, the only spell capable of repelling Dementors. The only known spell, that is. Voldemort hadn't been one to accept having a weakness, and thus he had conceived a spell of his own. 

Dementors fed on thoughts, memories and emotions, preferably positive ones. Given the chance, they'd even devour the soul itself. The Patronus worked by force-feeding Dementors their favourite food until they were given indigestion. Like moths drawn to a light, Dementors would slam their heads against a mindless source of endless positivity, the Patronus's spirit guardian, until finally they would have had enough. It was said that only those who held true happiness in their hearts could cast the Charm. 

Dementors were impossible to destroy, they could only temporarily be driven off. As Dementors reproduced by consuming enough positive vibes, the entire world would one day be overrun by darkness and despair. But that day was far off into the future.

However, Dementors didn't only consume positive energy, so Voldemort had created a reverse Patronus, filled with his hatred. It worked just as well to drive them off, but obviously people would begin asking questions if Ginny Weasley cast such an evil spell!

"NO! STAND DOWN!"

Out of the corner of her eye, Oleandra saw two adult Wizards burst into the compartment shouting, but they were too late. The Dementor raised its hood and performed the Kiss on her.

Oleandra's eyes glazed over; she felt as if she were stuck in quicksand. Her limbs were like lead, and her veins filled with ice. She heard shrill screams in her ears, and then, she saw it. 

It was as if she were watching an ancient television set from very far away through a thick window, but at the same time, she could hear the voices of the characters very clearly. There were two people in her vision, one man and one woman, but Oleandra couldn't make out the man's face, and the woman was facing away from her.

"Vee, how did it come to this," said the man sorrowfully. "It didn't have to be this way..."

"I'm sorry, I'm sorry," sobbed the weeping woman. "I never meant for any of this to happen…"

"You and your sisters, you're all the same," the man continued, an accusatory tone creeping into his voice. "Never happy with what you're given. Always wanting what wasn't meant to be yours."

"Please, I'll find a way —"

"Just leave me be. There's no point any more," said the man forlornly, turning away. "All is lost."

"NO!" screamed Oleandra, sitting up with a start.

A cry of pain came from above her. It seemed that she had slammed her forehead into somebody's nose. Oleandra touched her cheeks; they were wet with hot tears. She quickly wiped them away, trying to dispel the feeling of loss within her. That dream had felt awfully real, as were the feelings she had experienced. Emptiness, sorrow, regret, despair… and love?

"Here, have some chocolate," said one of the two men. "Go on, have a bite. You'll feel better."

Oleandra did as she was told. She felt heat return to her body as the sugar made her flush red.

"Dementors will force you to relive your worst memories," the man continued. "You must have seen something awful; you were out for a while."

"I don't understand," said the other man, scratching his head. "It performed the Kiss on her. By all rights, she shouldn't even be awake, much less responsive."

Oleandra didn't understand either. Those hadn't been her own memories; she was sure of it. And yet, they seemed oddly familiar. She closed her eyes; in her inner world, Mannaz was shining brightly. A milky white orb had formed around her soul; it seemed like the Cosmic Egg had protected her by itself.

Suddenly, a nagging feeling of doubt washed over her.

"Excuse me, Mr. Auror? Sir?" Oleandra said tentatively. "May I speak with the Dementor who attacked me?"

"Are you nuts?" said the man wearing the shiny Auror badge in disbelief. "You shrugged off the Dementor's Kiss, and now you're going back for seconds?"

"Out of the question," said the man with the chocolate. "Dementors drain happiness out of the air simply by existing. You'll worsen your condition."

"I'll sue," threatened Oleandra. "I have the full strength of the Greengrass family behind me."

"Okay, you win," said the Auror quickly. "But not for too long, okay?"