The Doctor was loaded down with magical books and Honeydukes candy when he returned to the Astronomy tower to find the TARDIS missing. "Oy! Lovegood, time to go! I've just returned from the Restricted Section and I-" He noticed the emptiness of the space before him. Immediately, he let his bounty fall to the floor and commenced to pacing the room in long, gliding steps, wielding his sonic screwdriver like...well, like a madman.
Then, he let loose a rapid-fire string of Gallifreyan vulgarities. Riddle missing. Lovegood missing. TARDIS missing.
The Doctor, at last, stilled, his expression stony in such a way that anyone with so much as a casual knowledge of his reputation would have been sent running by the sight of it. Riddle. If you've done anything to either of them, you're going to want to hide.
...
Riddle had not lied; they were, in fact, at Hogwarts. Or, more accurately, they were over Hogwarts. Higher, even, than thestrals normally flew, so that all of the castle (and some of the grounds) was visible to Luna.
"When are we, Tom?" Luna asked dazedly, running the tip of her wand over her lips the way she sometimes did when deep in thought. She was not in the ideal situation here.
"A few decades in my future," Tom answered with a slight smirk. "Are you going to stand right at the edge like that? I might push you off."
"I'm not afraid of heights, Tom. When are we?"
"I've just told you."
"And I suppose you won't be any more specific. I expected as much. Will you bring us back?"
"I don't think so," Tom said breezily.
"Hm," Luna sighed. Then, she whipped around, pointed her wand, and shouted, "Rictusempra!"
Tom was apparently not prepared for this one; he staggered back, contorting his body in discomfort and giggling at the sudden sensation of being tickled. It only took him a moment to recover, but in that moment, Luna raced past him to the TARDIS controls.
"Oh my..." Luna breathed, for once horrified good and proper. The TARDIS's controls were swirling with darkness and bitingly cold to the touch. "Tom, what have you done?"
A spell hit Luna squarely in the chest, and she fell to the ground, feeling as though she had lost more than half of her energy; now, all she wanted was to lie down.
"I win again," Tom said. "You're rubbish at dueling, Lovegood."
Luna was not interested in arguing that she was only in her first year, and not even well into her first year, at that. She instead repeated, a bit faintly, "What have you done to the TARDIS, Tom?"
"At the moment," said Tom, and he eased at one of the TARDIS's levers, "I am attempting to park it."
"You can't enter Hogwarts, Tom. You'll be recognized by someone...by Dumbledore. Meddling with time's illegal, you know."
"Oh, I'll get in. At the very least, I'll have to get you to the Hospital Wing before that hex takes full effect."
Luna tried to sit up, but the vertigo overtook her, and she passed out.
...
When Luna awoke, she was indeed lying in a bed in the Hogwarts Hospital Wing. The room was dark and full of the sound of sleeping...and whispering.
"James?" a boy's voice was saying. "What are you doing in here?"
"Well, you've hardly got a monopoly on the Hospital Wing, Moony. I'm allowed in, too."
"Yes, but what happened to you?"
"I was out flying and..." The boy paused, then went on cautiously, "Something distracted me."
"Was that something female?" the boy called Moony asked dryly.
"No," James protested. "There was this blue box hanging in the sky."
"A blue box?"
"Yeah. I nearly flew right into it; appeared out of nowhere, it did. Could've flattened me."
"Things don't just appear in the sky over Hogwarts, James."
"Well-contributed, Moony. I had no idea."
There was the sound of something smacking James.
"Ow! I'm just saying, it did appear. I know it's strange."
"Did you tell someone?"
"I might've mentioned it to Padfoot, before I blacked out. Really, Remus, I've been a bit busy."
As the conversation progressed, Luna quietly (and dizzily) rose from her cot and neared the two boys. They caught sight of her once she stood at the foot of Remus's bed.
"Can we help you?" James asked defensively.
"Just making sure you're real," Luna said dreamily. "One can never be sure, with voices in the dark. You might have been some breed of night terrors."
"Night terror?" James repeated. "Moony's a right terror."
"And James is a night error," Remus returned calmly.
Luna smiled. Her good mood faded, however, when she remembered that Riddle was now displaced into a period of time that might just know his name. Not his real name, of course; almost no one knew his real name. All the same...
"Who are you?" Remus asked her.
"Luna Lovegood," Luna replied.
"What year, what House?" James asked.
"Ravenclaw. The year's a bit wonky, though..."
"Wonky?" James repeated incredulously. "It's numbered one through seven! Which are you?"
At that moment, Luna's head swam, and she crumpled to the ground.
With muffled exclamations, James and Remus clambered from their beds and helped her to her feet.
"Are you alright?" Remus asked.
"Rather dizzy," Luna said unsteadily. "Got hit by a hex, and I'm not sure what kind...I might have over-estimated my strength."
"Which bed's yours?" James asked.
"I'll get Madame Pomfrey," Remus added.
Honestly, the boys' vigilance was an asset, because Luna was already sinking back into unconsciousness. All she could repeat as she did so was: "Where's Tom? Where's he gone? Where's Tom?"
...
When Luna woke once more, it was to a significantly-younger-than-Luna-was-used-to Madame Pomfrey spoon-feeding her some sort of potion that was nearly as thick as porridge. "There you are," the woman said. "You'll be needing another dose in three hours."
"Thank you, Madame Pomfrey," said a familiar voice at Luna's bedside; Tom had returned, only he seemed to have altered his appearance somewhat; Luna still recognized him and saw little difference, but a part of her was also aware that there was a spell warping his looks for others.
"Do not excite the patient too much," the matron said sternly. "She's already pale as a sheet."
Once they were alone- and truly alone, Luna noticed; the Hospital Wing was completely empty, apart from them -Tom relaxed back in his seat.
"Where's the TARDIS?" Luna asked him hoarsely.
"Parked it somewhere nobody will find it," Tom said.
"Is it in the Forest?" Luna asked.
"Yes," Tom said. "In a place only I know."
"In all the years Hogwarts has existed, you think there is such a place?"
"Yes," Tom replied obstinately.
"Well, you would know best, Tom."
"It's Taurus," Tom said. "While we're here, call me Taurus Black."
"You don't think the Blacks will notice you're not a relative of theirs?" Luna asked.
"I've said I'm from Albania."
"So you do finally get to join an old pureblood family," Luna observed lightly. "Does that make you happy, Tom? Er, Taurus."
Tom only scowled, upset that she had brought his blood status up. He, by now, knew well enough that Luna was not prone to filtering herself nearly enough before speaking, but that did not condone her audacity.
Luna closed her eyes for a second as her head throbbed. "You hexed me," she recalled.
"You tickled me," Tom returned. "Anyway, we had to get into the school somehow."
"And where have you been?" Luna asked, opening her eyes again. When she opened her eyes, it was always a bit like car headlights turning on.
"The library," Tom replied. "Reading up on 'Tom Riddle'."
"I assume you found nothing?" Luna deduced, drawing her knees to her chest quaintly.
"Oh, I found loads," Tom said, and there was a dark mania behind his eyes. "Turns out, I didn't even have to read anything; I could have asked anybody in the school. They all know the name 'Tom Riddle'."
Luna frowned. This was not how time was supposed to go. Had the timelines been altered so much that Tom never concocted his pseudonym? "What do the books say?" she asked.
"Apparently..." Tom began, still with that mildly disconcerting (and, were anyone besides Luna Lovegood to have seen it, far more than just mildly disconcerting) gleam in his eyes, but he was interrupted by a portly, brown-haired boy bursting into the Hospital Wing.
"James! Remus!" he shouted, then was brought up short when he saw that the boys he sought were not in the Hospital Wing.
"They've gone," Luna told him.
"Do you know where?" the boy asked, looking listless.
Tom and Luna both shook their heads, and the boy left with a partially dejected, partially determined air about him.
"Apparently," Tom continued, as though there had been no interruption, "I am a rather dark wizard." He let the words sink in for a minute before grinning a rather horrible grin. "Is that why you saw fit to go back in time and seek me out? You hoped to redeem the murderer?"
Luna only stared at him, but she could feel her heart constricting with every word he spoke.
"Oh, Lovegood," Tom sighed. "That's so you. But people don't change, you know."
"What a cynical thing to say," Luna answered, a bit high-pitched. "Or, if not cynical, very Muggle of you."
Tom was on his feet in half an instant. "What's that supposed to mean?"
"Magic is the embodiment of change, Tom. Your upbringing is showing, if you think that it's impossible to fundamentally change a person."
Tom grabbed Luna's arm hard. "And who says I'm a person, Lovegood?" he seethed through a laconic smile. "You naive little girl."
Luna only smiled, the daydreamy smile that she adopted whenever older Ravenclaw girls picked on her; she knew that it drove them crazy. "If you're not going to kill me, Tom- and I suggest you don't, considering who the Headmaster here is -you should calm yourself, I think."
"I won't spare you because of Dumbledore," Tom told her before releasing her arm. "I'll spare you because, stupid though you are, you're mine."
Luna would have shivered, and she likely would later, once she was alone in her Ravenclaw dormitory, but at the moment, she was more curious than anything else. "I'd like to think I'm my own," she mentioned offhandedly.
"I'm sure you'd like to think a lot of things," Tom said.
"You think you're the first person to insult me, Tom?" she asked, angling her head sideways. "Really, you are silly." Silly, incidentally, was not something she ever thought she would be calling Voldemort.
"Silly as a person who thinks she can just go back in time and change the heart of Thomas Marvolo Riddle?"
The sound of something being knocked over at the other end of the room startled both of them. Immediately, Tom fired a spell (wordlessly) into the empty air. The spell hit against something, and an Invisibility Cloak fell away to reveal James and Remus and another boy with overgrown, dark hair. All three of them looked flabbergasted.
Tom reeled back to fire a presumably-much-worse spell, but Luna tackled him with a hug and refused to let go until violently shoved and deposited back onto her bed. By that time, the three boys had managed to sprint to the exit and out of the Hospital Wing.
As Tom turned on Luna, she queried, with the smallest of triumphant smiles, "How much do you reckon they heard?"
Tom, for several moments, looked as though he might physically smack her. Instead, he replied, in a strained but cool voice, "Enough." Then he grabbed her arm again and dragged her from the bed. "We're getting back to the TARDIS."
Luna said nothing and simply let him drag her. There was no need, after all, to say anything; she had won and he was livid. A part of her was somewhat afraid.