a.n. While not entirely necessary, I recommend reading Of Ponds and Potters before reading this, as I will be referencing the events of that story throughout this one. If you insist on not reading these stories in order, then I suppose you should at least know that Amy and the Doctor helped defeat Voldemort that one time he tried to team up with some daleks to take down Hogwarts, back when the Marauders were in school. ...It sounds a lot less weird than that when you read the fic, I promise.

One - The Invitation

The last time Amy had seen the Doctor he had been in the swinging seat beneath the console, goggles on and shirt sleeves rolled up as he worked on something or other. He'd tried explaining what he was doing, but through the hand waving and tangents Amy hadn't been able to decipher his actual goal, so she'd let him be and wandered off to find a new book to read. She had thought that he'd be fine by himself for a few hours, but alarm bells started ringing in her head when the TARDIS began swinging violently from side to side and she was practically thrown out of the armchair she'd curled up in.

She made it to the console room at the exact same time as Rory, the two of them coming from opposite sides to corner the Doctor, who was frantically running about the controls and barely paid them any attention.

"Doctor, what's going on?" Amy asked, grabbing a railing for support and digging the heels of her boots into the floor. Rory sidled up beside her, and her spare hand fell into his instinctually.

"Not quite sure, right now," the Doctor mumbled, brows furrowed as he swung off the end of the scanner, which was flashing statistics across the screen too fast for her to catch. "But I'm working on it! Should have an answer for you any moment now, just as soon as I get her stabilised and then -"

As suddenly as it had started, the rocking sensation stopped. The Doctor let go of the scanner and held his hands out to the side, as though testing his balance. His shirt sleeves were still rolled up and his goggles had been pushed up into his hair, so his fringe stuck up at an unnaturally high angle behind the lenses. Amy wanted desperately to laugh, but the concerned look on his face was enough to stop her. She and Rory straightened up, and she waited for the promised explanation. When it didn't come, she tilted her head to the side and prompted, "Well?"

The Doctor blinked at her as though coming out of a trance. "Well?"

"What the hell was that?"

"That was, ah, well, you see -"

"You have no idea, do you," Rory deadpanned.

The Doctor looked a bit sheepish for approximately half a second before launching himself back over to the console and pressing a string of buttons in quick succession with an air of intense purpose. "I have some idea, Rory. In fact I have more than some of an idea, I probably have half an idea - maybe even two thirds of an idea if you stretched it out, actually -"

"And are you going to tell us this two-thirds of an idea you have?" Amy pressed, folding her arms over her chest and leaning against the panel beside him.

He pulled the goggles off his head and his hair flopped forward into his eyes. "Something's pulling us. Or, rather, something was pulling us. It's stopped now."

Amy looked over to Rory, saw that he was just as lost as she was, and turned back to the Doctor. "You mean something overrode the TARDIS controls?"

"In a sense, I mean that's one way of looking at it..." At Amy's glare the Time Lord's words died. "Yes, that's what I mean. Kind of, not really, though, don't look at me like that, Pond."

"But what would have the power to do that?" Rory asked. "I thought nothing was powerful enough to override the TARDIS?"

"You're right, and that's what interesting... It's kind of like someone sent out an invitation, or offered us a lift, and the TARDIS accepted that offer and now here we are." The Doctor clapped his hands together and smiled in a way that Amy thought he probably intended to be reassuring.

Amy mimicked his smile. "Sounds peachy. And where, exactly, is here?"

He tossed the goggles onto the console and barrelled past them, leaping over the entire set of stairs and landing on the bottom level with a thump. He pushed his sleeves down and grabbed his jacket off the coat rack with a flourish. "Scanner's gone all wibbly, so we must be somewhere good!"

"Oh yeah, anywhere that interferes with ultra powerful and normally reliable advanced alien technology must be good," Rory said, trodding down the stairs after him.

Amy nudged him in the side, although if she was being honest she didn't entirely disagree with the sentiment.

The Doctor pouted. "I expected better of you, Rory. Where's your sense of adventure?"

"Where's your sense of self preservation?" he countered.

The alien shrugged into his coat. "Lost it long ago. Not sure I ever even had one, to be honest."

Amy rolled her eyes. "Why am I not surprised?"

The Doctor winked at her and stepped outside, and of course the Ponds followed.

They'd landed at the edge of a forest. In front of them lay a picturesque expanse of green grass, and behind them trees towered high into the clear, blue sky. Birds were chirping, and in the distance Amy could faintly hear conversations, carried on the gentle breeze.

"This doesn't seem too bad," Rory announced, looking out across the grass. "You've definitely landed us in worse places."

The Doctor craned his neck to peer around the back of the TARDIS, inhaled deeply through his nose, licked his finger and held it out to the air. Apparently unsatisfied, he kept sniffing, walking a full circle around the ship and taking three large strides forwards into the clearing before stopping. "Something feels off."

Amy watched him closely as he whipped the sonic screwdriver from his inside pocket and tried to scan the area. It must have malfunctioned, because he began hitting the thing against his palm and swearing under his breath. Something niggled at the back of her mind, a memory triggered not by scent or sound alone but by the unique sensation this place gave her. She struggled to properly grasp the idea, but couldn't stop it from forming. Her eyes widened and she grabbed the Time Lord's elbow. "Doctor, doesn't this place look familiar to you?"

"Familiar how?" he muttered, preoccupied with fiddling with the sonic.

"Familiar like parallel universe, familiar?"

At her words his hands stilled. He slowly raised his head to meet her eye, and she felt her stomach twist at the intensity of his stare.

Rory broke the tense moment by saying, "Oh, no, no, I am done with parallel universes, thank you very much. No more travel outside this universe where we are safe with this TARDIS, that's what we agreed after that last trip -"

"Not that parallel universe, Rory," Amy interrupted.

He blinked, perplexed. "You've been to more than one parallel universe?"

"Once, when you were..." She hesitated for a fraction of a second, and the Doctor jumped right in.

Stowing his sonic, he explained, "When you were wiped from existence, during that time between when the energy from the crack absorbed you and when you came back as a plastic centurion, Amy and I ended up in a parallel universe with an alternate her and an alternate you."

Rory, understably, took a moment to process this. He opened and closed his mouth a few times before any words came out, and then he finally asked, "And you think this is that same universe?"

"I think so, yes." Apparently satisfied with Rory's acceptance of this new information, the Doctor began walking away from the TARDIS. Amy hurried after him, and Rory hurried after her, and the further away from the forest the three of them got the more certain Amy was that they were in the same place.

Rory fell into step beside Amy. "So what happened last time you came to this parallel universe? Are there any particular dangers I should look out for, any rules I should know about meeting an alternate me?"

The smiling faces of Lily Evans and James Potter flashed to Amy's mind. She wondered how she was ever going to be able to explain everything that had happened to Rory. "I don't think there are any dangers. Lily and I didn't seem to have any issues."

"Lily, is that your alternate's name?" Amy nodded, and Rory fell silent, maybe sensing her sombre mood. She resolved to tell him the full details of that adventure when they were back safe in the TARDIS later on.

For now, they walked on in silence just a few steps behind the Doctor, until they crested a hill. Before them stood a great, grey castle, towers and spires piercing the air in a way that took Amy's breath away. Great wooden doors were flung open and a small stream of students wearing black robes passed through, joining their friends milling about on the grounds. Up higher the sun reflected off arched cathedral windows, casting bright rays of light back out into the afternoon. Beside her, Rory gasped.

"You were right, Amy," the Doctor said. "We're back at Hogwarts."