"Try it if you want to."
Luna looked up; Tom had caught her fiddling idly with her time turner.
"It goes backwards and forwards, depending on which way you turn it," he told her.
"But I can't go before your birth or past your death, right?"
"I'm never going to die, Lovegood."
"Why not? You want to leave me plenty of options?" Luna was mostly unaware of her own joke; she was feeling a bit twitchy around the hands. She had thought to find precisely the first time that she met with Tom Riddle- or any time that she met with him, really -and to warn herself and Mr. the Doctor of the coming inconvenience, but...
...but that would probably be like spilling hot soup all over the timeline, or the time blanket, or however it was that Mr. the Doctor explained it. It wasn't right. It was probably dangerous, double-dipping that way.
Still.
She could at least go back to a time when it wasn't so deeply unsettling to have Tom staring at her the way he was now; she did not like to be deeply unsettled. "How much is each spin worth?" she asked him.
His eyes gleamed. "That depends on how hard you flick it."
Luna exhaled exaggeratedly. "I'll try at random, then? Lovely." She started to spin the hourglass.
...
"Extension charm?" the twins said in unison.
The Doctor pouted. "I'm going to stop bringing witches and wizards into my TARDIS; you lot have no sense of wonderment."
"Who are we hiding from?" one twin asked.
"Hiding? Who says we're hiding?" the Doctor squeaked out.
The twins exchanged a look. "You were looking at the map, then you suddenly went all weird and shoved us into a blue box across the school from where we were standing?" one of them suggested.
"Right. Fair enough. Tell me, Weasley twins, do you ever have a memory that is completely gone from your mind until, say, you see a photograph of it, and then you remember it in full, rich, gooey detail?"
Again, the twins exchanged a look. "I suppose," the same one (Maybe he'd call this one "Talky One", although, from his recollection of the books, it was probably Fred.) said.
"I've been here before," the Doctor told them earnestly.
It was meant to be a cryptic statement, but almost immediately Talky Twin answered, "What, you mean like time travel or something?"
"That's illegal, you know," the other twin said, but not with nearly the disapproval that the comment warranted. In fact, he was almost smiling.
The Doctor decided that the Weasley twins were most definitely to be trusted. He adopted a casual (read: immensely cool-looking) lean against the TARDIS console. "Well, you are in my time machine."
"Time machine?" the twins repeated, again in unison.
Ah, there was that sense of wonderment.
"You've got a time machine at Hogwarts, and-"
"-and we didn't know about it?" Talky Twin finished, sounding affronted.
The Doctor brandished his finger. "Correctamundo!" he exclaimed, then winced. "Oh, I said I wouldn't..."
"And you use this thing?" Talky demanded.
"Yup."
"Can we?"
"Yup. No!" the Doctor hastily corrected himself. "No, no, absolutely not."
This time, the look the twins exchanged was a purely mischievous one. "Doctor," Talky said, "you're taking away our Map."
"As well as robbing the school of the wholesome trouble-making that the Map can enable us to bring about," Less-Talky added.
"Oh, come off it. You give it away in a year anyway."
It didn't take the twins nearly the time that the Doctor expected to recover from this bombshell. "Even better," Talky replied. "You're actually changing time by taking it from us."
"The least you can do is let us have a go on your time machine."
"Okay, first: That is about the farthest you can get from 'the least I can do'. Second: I might as well change time; time is already changing here, now that Lovegood-" He stopped himself, feeling like an absolute dunce.
"Lovegood?" Untalky repeated. "Xenophilius Lovegood?" Oh, no, that would make just too much sense.
"You let Xenophilius Lovegood have a go, but not us?" Talky said incredulously.
"No..." the Doctor answered, scratching at the back of his neck. "Forget I said 'Lovegood'. Strike that from the record."
"Not his child, then!" Talky said, catching up too fast. "The eleven-year-old!"
The Doctor straightened. "Hey, I will have you know, when we first traveled together, she was nine." Since that evidently wasn't nearly the game-changing defense that it was meant to be, the Doctor went on, "And we were being chased by Daleks." This only earned him uncomprehending looks. "And what does age matter to me anyway? I'm at least a thousand by now." There. Now the twins were almost completely distracted. Good; he feared he was this close to making them companions, and he could only imagine what trouble they could cause with, say, the Jadoon. "We are getting off-topic," he said at last. "The point is, I've been here before and I'm here now and both of those statements mean the same thing. And neither of me are alone."
The two of them actually took a few seconds to digest this. The Doctor found himself relaxing, glad that now they were finally grasping the gravity of the situation.
"So there's a second time machine somewhere around the castle," Untalky surmised.
The Doctor scowled at the twins. "You two are the absolute worst people to talk to, do you know that?"
...
Clearly, it wasn't just time travel; Luna appeared in the Slytherin common room of Hogwarts.
"But..." She stood perplexed for a second. She was being stared at by a whole host of unfamiliar Slytherins, with no Tom in sight, but that wasn't important right now. "But surely that's cheating," she protested aloud. "No one can Apparate into Hogwarts."
"Lovegood." She turned around; Tom was standing at the room's entrance, dressed in his Slytherin robes, looking about her age. "It's about time."
"How did she get here, Riddle?" an older Slytherin demanded.
Tom regarded the boy with distaste. "Magic, I assume, Bowman."
Bowman wore an expression that clearly said that only Tom could get away with such cheek.
"I don't understand," Luna was murmuring to herself. She almost reached for the time turner, but then she turned the motion into a casual pat at her own hair; the Slytherins certainly couldn't know about the power that she was wearing around her neck. And what power it was! "There's no way..."
"Lovegood," Tom addressed her. "Come with me."
She followed him out of the common room, into a hallway of the dungeons. They stopped a short way from the door, and he cast a Muffliato charm before looking her over.
"So it seems I do manage it, in the future," he noted. "No TARDIS, no Doctor."
Luna was already frowning a bit, so she didn't have to change her expression much at his comment. "You'd been planning it for this long?"
"Of course."
"What year is it for you?"
"Still second."
Now, Luna looked him over. "I'd ask if you're lying, but that might be a bit pointless."
Tom grinned. "Maybe a bit. Come on. I want to show you something."