The Doctor was able to ignore the wrackspurts up to the point at which they started whispering names.
"Rose Tyler."
"Martha Jones."
"Donna Noble."
Then, like a fool, he stopped. "How are those names here?" he demanded. "This is Luna's mind! She doesn't know those names."
Then the voices changed:
"When was the last time you danced?"
"He never looked at her twice."
"Donna Noble has been saved."
"LUNA LOVEGOOD DOES NOT KNOW ANY OF THIS!" the Doctor shouted.
The deep voice of the Great Intelligence replied, seemingly emitted by the trees: "No, but I do."
"You're inside her mind," the Doctor protested. "Nothing can exist inside her mind that she doesn't know about."
"She put the wrackspurts here, which are creatures which have access to one's thoughts. I only made use of them."
"Goodbye, sweetie."
"I'm not listening!" the Doctor declared firmly, then strode on, reaching for his screwdriver to run a scan on his surroundings.
His screwdriver was not in his pocket. He backtracked, searching the ground, and one of the glowing creatures appeared right in front of his face before vanishing.
"Nargles are certainly mischievous creatures, aren't they?" the Great Intelligence intoned gaily.
The Doctor's face went almost blank, which was never good. "Give me back my screwdriver, and, while you're at it, leave Luna Lovegood alone, or you'll really regret it."
"I will?" the voice chuckled, and, suddenly, hundreds of glowing faces appeared all around the Doctor, snarling.
On this cue, the time lord chose a direction and ran.
...
Instead of opening them, Luna shut her eyes tighter. The Snorcack was breathing down into her face, and there didn't seem to be any light outside.
"Mr. The Great Intelligence?" she said quietly.
"Yes?" the voice replied.
"Sir, you can't kill me inside my mind."
"I can't?" The voice feigned disappointment.
"No." Her voice cracked.
"Why can't I?"
Luna found the courage to open her eyes, then. The Snorcack was still there, still terrifying in theory, but she stood and placed a gentle hand on its nose. The creature stilled. "Because this is my mind," she whispered, crooning, sort of, to the beast. Then she wrapped her arms around its neck and pressed her face into its side. It tensed, but she remained where she was. "My mind," she said again, "and I'm not afraid of you."
The Snorcack disappeared, and the world seemed to swirl around Luna.
She shouted into the abyss, "My mind won't hurt me!"
The Great Intelligence answered smugly, "I will."
Then she ground vanished from under her, and she was falling.
"I'm not falling," she decided aloud. "I'm flying."
And her surroundings chose to agree with her; suddenly, she realized that gravity was going the other way, and she was really only flying upside-down.
"Silly girl," the Great Intelligence said impatiently. "Everything here will hurt you."
Then she landed in a meadow- a different meadow than before -full of bright red flowers like something out of a Muggle film...and Daleks. Lots and lots of Daleks.
"EXTERMINATE!" they all shouted at the same time, and Luna smiled a little because she'd been through this before; Daleks were so, so easy to stall.
Then she saw that they weren't aiming at her; they were aiming at her parents. Her mother, small and beautiful, and her father, lean and smiling. Oblivious. And then every weapon went off at once, and they were gone.
"No!" Luna screamed, and thunder and lightning tore the sky. She crumpled to the ground and hugged her knees to her chest. It's not real, she reminded herself, and the words rang audibly here. It's not real.
"It's very real," the Great Intelligence argued. "Your reality exists in your mind. Unfortunately, I own it now."
And then Luna felt a bit of very real fear, because she knew exactly what existed in her mind. She knew exactly.
On cue, a swarm of cornish pixies assaulted her, tugging at her hair and scratching at her face, aiming, it seemed, for her eyes. She curled into fetal position.
"You said that your mind won't hurt you," the Great Intelligence said, "but that's all it will do. It will torture you and tear at you and plague you forever, and there's nothing you can do about it."
THIS ISN'T REAL! Luna's mind yelled, and Luna, herself, called out, "The question, then, becomes: What's in it for you? What do you want with me?"
"I've told you: The Great Intelligence needs a new host. Your fear is merely for fun."
"By host, you mean body. So you can control me in here. Right?"
There was no reply, but Luna's heartbeat had accelerated, and it rocked the world, blurring lines everywhere.
"A mind is like a TARDIS," Luna whispered, gradually working it out. "It's bigger on the inside and many places at once. So right now, I'm inside of another me. A me that you're controlling."
"Very clever," the Great Intelligence intoned blandly.
Luna stood, and the cornish pixies promptly heightened their attack on her. "Mr. The Great Intelligence, you shouldn't have brought me here," she told him softly, "because I'm about to help me destroy you." Then she ran into the darkest shadow and disappeared.
...
When the Doctor cleared the last of the trees, he found himself in the same meadow as before, TARDIS and all.
"What?" he said allowed.
Clara appeared to him, then. Her expression was far more urgent, this time, and she handed him a stick...no, a wand. "Take this," she ordered him.
"But...No," he protested. "I'm not a wizard. I don't need a wand; I need my screwdriver."
"You can't get your screwdriver back until Luna gets her mind back," Clara said quickly. "You have to find her, and you have to give her this."
"Where is she?" the Doctor asked.
"The wind will take you there. The Great Intelligence wants you to find him. Run." Clara placed her hands on either side of his face and said, earnestly, "Run, you clever boy, and find my daughter."
...
When Luna emerged from the shadow, she found her bare feet smacking against some sticky sort of mud.
Quick sand? was the first thing she thought, and immediately after, the mud started to swallow her.
Stupid, she cursed herself, and a chorus of insults hurled themselves at her from the darkness. Stupid girl. How can you win? You will fail. The Great Intelligence will always be stronger.
"That's not me," Luna said serenely. "I can tell when it's my voice and when it's yours." She had sunk to her knees, now, and the sand was speeding up.
Fine, then, I'll just sink, she decided. I'll sink into the underneath and see where I land. You can't scare me, Mr. The Great Intelligence.
And then her mouth was under, and her nose, and her eyes, and the top of her head, and she landed...Well, it wasn't really landing. It was more like hanging suspended in darkness. But she could breath, so that was good. She swam through the dark, and then a scream cut through the air, startling her so much, she couldn't focus on her inner peace. She started to fall.
The scream was her mother's. It was the same scream that she'd heard that afternoon when she went to call her mother to lunch only to find...
This. Is. Not. Real.
Luna stopped thinking, stopped remembering, stopped fearing, stopped everything, and just breathed. She put her mind on pause and focused on air. Her falling stopped, the screaming stopped, but the Great Intelligence's voice started to speak.
"Clearing your mind, little girl? Thanks. I needed that."
And Luna felt as though some sort of potion had been spilled all over her, because her skin began to burn, and all she could do was writhe in midair. "Ssssssstop," she panted.
"Do you want to see the you that you are in this time?" the Great Intelligence purred, and then a light seemed to come on and Luna saw...her own face. Only, she was older, and there were scars, and she was dirty and slumped against a mirror, panting and looking haunted.
"Luna?" the voice belonged to a boy with brown hair and a kind, round face.
"Neville," the older Luna said in a distant voice, trying to maintian a smile while an all-out war went on inside of her mind.
"Are you alright?" the boy, Neville, asked. "Was it the Carrows?"
"I'm-"
The light went out, and young Luna found herself suspended in darkness again.
"Dear me," the Great Intelligence droned with mock-pity. "I think you've just been caught by the Death Eaters."
"Death Eaters?" Luna repeated, alarmed. Voldemort comes back?
But then she regained control of herself. This was what he wanted. He was thriving on her fear.
Whatever potion or acid that had been pouring on her skin began to itch and burn at her muscles. She let loose a sob. "You c-can't kill me inside my mind," she said, and she was mildly chagrined to find that she was sort of whimpering. "I saw myself grown up. That means I m-make it through this."
"Yes, but you've seen what you become," the Great Intelligence replied, almost soothingly. "Does it matter?"
Luna felt her eyelids shutting.