I'm a fan of both Doctor Who and Harry Potter. This set of stories is the combined, schizophrenic brainchild of myself and my fellow Doctor Who and Harry Potter fans, who all came together on Monday after a particularly interesting crossover discussion.

The idea stemmed from a question that popped into my head that afternoon: "If the Room of Requirement can make anything that you want (within reason), than can it open up to give you the bigger-on-the-inside room you step into when you enter the Tardis?"

We all decided to try and make our own one-twoshots for this crossover, with each person being taking a year, Doctor regeneration, Harry Potter character, and alien conflict of their choosing, with instructions to tie the entire thing into some of the vaguely-explained parts of Harry Potter. My prompt: 9th Doctor, 3rd year, Trelawney prediction, Silence, Remembrall, Filch, and Boggart.

The game is on. I make two moves, the rest of my fellows make the other five moves. Let's see what comes out.

Please, no flaming. Flames will only be used to light up some of Fred and George's fireworks, and Professor Snape will have an aneurism if they set off another batch on the Quidditch pitch again underneath the Slytherin team's broomsticks.

It began, like most days at Hogwarts School of Witchcraft and Wizardry, with the usual chaos.

The birds were crashing into the Whomping Willow, Peeves was spitting Ink Pellets at angry second year girls, Moaning Myrtle was sulking in her haunted toilet, Professor Sprout was watering a new batch of baby Mandrakes, the Giant Squid was scooping up screaming first years from the deep end of the Lake, Fred and George Weasley had tied a lit Filbuster's Firework to Mrs. Norris' tail and let her loose in the Sytherin Common Room, and Filch was threatening the students with various scenarios of gory murder if he caught so much as one more biting teacup sent to him in the mail.

And in the tower of the school's resident Divination Professor, sat two of Hogwart's staff, one a rather stern-looking woman who was bored out her mind, the other an eccentric, frizzy-haired woman with coke-bottle spectacles who was completely immersed in her work, and just the tiniest bit batty.

Professor Sybil Trelawney was sitting cross-legged on a large, fluffy, powder blue poof pillow in the middle of her classroom, a crystal ball held in a claw-footed metal basket on the round table in front of her. Her enormous eyes, magnified quite magnificently by her coke-bottle spectacles, were staring intently into the huge orb as if it contained the secrets of the universe, as her hands gripped the edges of the table in excitement. Her many shawls, dripping with beads, little silver bells, and jangling coins, glittered dully in the dim light of the smoky, stuffy room.

Professor Minerva McGonagall, head of Gryffindor and the boarding school's resident Transfiguration instructor, was not quite so enthusiastic. She had good reason for this, seeing as she'd been here for several hours now, and absolutely nothing, at least from what she could see, could be clearly discerned from the ridiculously oversized crystal ball that her fellow colleague was staring into.

Every so often, she'd see the self-boasting "Seer" get up and walk around, pacing back and forth as she flung her hands up in the air and muttered things under her breath. Other times, the frizzy-haired woman would bolt from her seat and dash to the window, staring at the clouds lazily drifting by outside as she began making indecipherable calculations on her ring-laden fingers. The air was thick with clouds of burning incense, drifting in whorls and spirals of smoke into the muggy air, leaving McGonagall dizzy and with a pounding headache.

I wish she'd open a window, and let out some of this blasted smoke. But no, she's too stubborn, she says that it would "disturb the balance of energies in the room". It's a load of rot, that's what it is. I swear, if she asks me if I "see" anything in that ridiculous hunk of crystal so much as a single time more, I'll turn a blind eye the next time Peeves decides to "borrow" her crystal balls to juggle over her head, like last Tuesday.

Her musings were interrupted out of the blue by a sudden gasp from Trelawney, as the Divination Professor lurched over in her seat, her breathing ragged and shallow. Concern washed over her for her colleague, and McGonagall approached her, about to ask if she needed to go to the Hospital Wing and get a looking-over from Pomphrey.

She took a step back in shock as Trelawney suddenly sat straight up, her hands jerking and twitching madly; her eyes rolled in their sockets, and suddenly she spun around, grabbing McGonagall and clutching desperately at her shoulders with bony fingers, her grip painfully strong as she looked into the Transfiguration Professor's eyes and began, choking on the words as she did so, to rasp out something.

"He...he is coming. Shining, glimmering gold, whorls and winds of golden light..."

McGonagall stared at her, feeling confused and somehow uneasy. "Sybil, what is it? What do you mean? Who's coming?"

Trelawney let out a rasping breath, continuing to speak in that awful voice. "He's coming, coming in..."

"A what, Sybil? Tell me who he is, and what he's coming in! We need to tell the Headmaster!"

"A box, big and blue, turning and turning round and round, like a time turner that never ends...

"He will come in the box, and bring forth destruction in his wake,

And enter the castle through a place of green and nature,

Then later again, from within, in the place where everything is, and yet isn't,

The sum of all fears will be there to greet him then, the fabric of time itself warped under the full moon,

And the silence, the silence will fall..."

Trelawney gave a low, guttural moan, as if in some sort of pain, and then collapsed against the front of McGonagall's robes, shivering as she rocked back and forth on the balls of her feet, her huge eyes wide and unblinking.

McGonagall stared at her for a moment, pondering what had been said, before filing away the information in her mind to tell the Headmaster about later. Reaching out a hand, she hauled her colleague to her feet, wrinkling her noise as a rather strong scent of sherry became clear. Sighing, she looped an arm around Trelawney's bird-thin waist and helped her walk, somewhat unsteadily, out of the room and to the Hospital Wing.

If this really is a prophecy, I hope to Merlin that it never comes true. It's bad enough that it's been made partly due to overdose of cooking sherry...

High above the grounds of Hogwarts, a strange sight could be seen hurtling downwards, towards the Astronomy Tower: a 1960 vintage blue London Public Call Box, emitting smoke from the seams of the door in front, and from the windows set into the door, rapid, golden light could be seen, flashing on and off like a badly lit neon sign.

Inside this box was a man, a madman wearing a black leather trench coat and looking almost comically upset at the flashing, blinking lights beeping and buzzing wildly upon his ship's circular control panel and dashboard. "Oh come on, don't fail me now, it was just a little temporal flux!"

There was a sudden banging noise from another part of the ship, the floor under his feet creaking ominously, and the man winced slightly. "Ok, so maybe not a little one, but I swear that I didn't know it would cause this to happen!"

More creaking, and one of the screens for monitoring the outside suddenly flickered to life: a full view of the rapidly approaching Astronomy Tower.

"Ok, ok, I get it, bad choice of words. Don't worry, I'll get us out of here, I promise. Just give me a second to set the new coordinates-"

CRASH. The inside of the ship suddenly trembled dangerously, forcing the man to grab hold of the nearby safety railing to keep from falling over. "What the bloody hell was that? Did we hit something?"

He looked at the screen, which had changed to show that the ship had somehow hit some sort of invisible barrier, flickering very faintly in a light pink color, surrounding the Astronomy Tower, as well as the rest of the castle, in what appeared to be a faintly visible, protective bubble. "Well what do you know, they've got a force field set up here! Not a bad job either, if it can keep you out, eh, old girl?"

The ship's walls hummed slightly, the noise giving off the impression of agreement.

"Well, now that that's done, mind telling me just where we are, then?"

The screen from earlier changed, turning black, as green block letters appeared to form the words: HOGWARTS SCHOOL OF WITCHCRAFT AND WIZARDRY, SCOTLAND, UNITED KINGDOM, EARTH.

He grinned, clearly amused. "Ooh, we got us a magic school then, hmm? Well, isn't that neat, never been to one of those before. Let's take a look!"

Somewhat unfortunately for him, before he could get back to the control panel to direct the ship to land properly, the "force field" around the school took full effect. The ship ricocheted off, and was thrown back into a nearby, rather ugly-looking tree on the grounds. The blue box crashed into the center, getting entangled in the knobbly branches. The ship's lone passenger was knocked off his feet onto the floor, landing on his back with a grunt of pain.

As he get up off the floor, he looked out the door windows to see what they'd landed in. "Well look at that," he commented offhandedly, "we crashed into a tree."

His eyes widened in surprise as one of the tree's many branches suddenly swung forwards and hit the door with the force of a small battering ram. The ship shook and lurched forwards.

"Dammit. Run a scan on this tree, I need to know what species it is!", he shouted, shoving a hand into his trench coat pocket and pulling out a bizarre, metallic-looking screwdriver. He pressed his thumb against a button on the tool's side; the top lit up. Instantly, he ran to the control panel and pulled several levers, causing a shield to go up around the ship. The tree swung several more branches, but this time the effect was little more than a slight tremor of the shields, nothing major.

The screen lit up with a new message, several rows of data appearing alongside a full view of the tree they'd hit. A title appeared on the top of the entry: THE WHOMPING WILLOW.

He looked at the title in dismay. "Great, just great. Of all the trees to land in, it had to be the one with anger issues. What are the odds of hitting the only tree for miles that hits back?"

There was no answer, save for the repeated failed attempts of said tree to pulverize the ship and its occupant.

He sighed, feeling rather annoyed. "Well, there's got to be people in that castle who know what they're dealing with, if they built a castle right next to the damn thing. Maybe one of them has an answer for how to get us out of here without damaging it further..."

The ship vibrated under his feet, and he felt a sharp shock of electricity surge through his fingers from the control panel. "What, it's not like it did the tree any good for us to hit it, either! How'd you like it, if something as big and mighty as a Tardis hit you?"

The ship hummed slightly, the lights up above glowing butter-yellow, and he knew his ship was laughing, clearly amused at being referred to as "big and mighty".

After a moment, he clapped his hands together, a grin threatening to split his face in half as he understood that he'd been forgiven. "Well, it seems like we've got our newest adventure, then, hmm? I'll go get someone to help fix this thing so we can go, and you keep watch and annoy the tree by keeping those shields up. It looks like we can't travel through the shields covering the castle, but that doesn't mean I can't use my Screwdriver to tweak them enough to let me slip through."

The Tardis hummed in agreement. He headed over to the door, giving the railing an affectionate pat as he did so. "If I'm not back in a few hours, you can likely assumed that I've been arrested, married, or couldn't find any bananas yet."

The answer was several gentle flickers of the upper lighting, as if the Tardis was laughing, and then the doors opened.

He looked out of the big blue box, to the protective, shimmering shield a few feet away from the door that kept out the swinging branches, and laughed. He promptly flung himself forwards, grabbing the doorway at the last second, and ending up grabbing the side of the ship, climbing up like a monkey until he'd gotten to the top. He stared for a long moment, calculating when and where to leap. "Let down the shields a sec, I'm going to jump down!"

The shield obligingly dissipated for a split second; the Whomping Willow brought a branch down like the swing of an executioner's axe, and he jumped.

The branches, by sheer dumb luck (and a few well thought-out calculations), missed by a hair's width, and he landed on the ground, dazed but unharmed.

Getting up and dusting the dirt of his clothes, he set off in the direction of the castle, hoping to find someone to help calm the angry tree.

As the Greenhouses came into view, he grinned, pulling out his Screwdriver. Hopefully they won't mind if I save them the trouble and just let myself in...

The Greenhouses at Hogwarts were empty due to it being the daily lunch hour, leaving Neville Longbottom free to stay and tend the greenhouse's section of harmless plants and healing herbs in tranquil silence, thanks to the permission given by Professor Sprout. His gift in this morning's post, a new Remembrall from his Gran to replace his old one, sat beside him on the table, the smoke inside warping and twisting like a tiny grey hurricane. He was glad that he'd gotten the new one, though as he looked back on it, he couldn't really remember what had happened when he'd first opened the package to get it in the first place. Oh well, maybe I'm just tired, everyone's memory's a bit fuzzy when they're tired.

Still, he couldn't help but feel that he'd forgotten something important. But what was it?

The sound of the door's lock clicking open met his ears, and he straightened up and turned around, certain that Professor Sprout had come in to check on him, but it wasn't Professor Sprout who came in. Instead, he found himself staring face to face with a tall, straight-backed man in a black trench coat, holding the most bizarre-looking wand he'd ever seen.

His hand reached for his wand, pulling it out of his robes and pointing it, shaking slightly, at the stranger. "W...Whoever you are, don't come any closer! Who are you, and what are you d-doing here?"

The man gave him a confused and slightly pitying look, seeing his only means of defense trembling due to his fear. He pulled a small, rectangular object out of his coat pocket, looking a bit like a pocketbook, before flipping it open and holding it out to him. "I'm the Doctor, I'm here to ask you about the tree out on the grounds. I've never seen one like it before, I've only seen an entry on it. Mind telling me why it's attacking my ship?"

Neville looked at him, confused, as he took the object into his hands and studied it. The paper shown read:

Doctor John Smith, Specialist of Arboreal Magical Oddities

Place of residence: 42 Gallifrayen Ave.

The boy looked up, feeling a bit less skeptical. Well, he's got papers, at least. Where's "Gallifrayan Avenue"? I've never heard of it, but it sounds foreign, so maybe he's from an out of the way town of something from the north. And if he got through the school wards, he must not be intending to do any harm to the school or anyone in it. But if he's a specialist on magical trees, why doesn't he know what the Whomping Willow does? Shouldn't he know about it?

He turned to study the man in front of him. The "wand" he held in his hand was unlike any Neville had ever seen before; he didn't think it was even made out of magical wood, the tool looked like it was crafted out of some sort of metal, like a muggle gun.

What kind of magic can a wand like that even do? Does it even have a magical core in it, or does it run on those muggle battery things Hermione told me about?

His appearance wasn't like a wizard's either; though it looked a bit like one, that trench coat was certainly not a robe, nor were the jeans and dark shirt, or the boots, and somehow, Neville knew that he didn't seem the type to endear himself to muggles at first glance either. The trench coat gave off a feeling of danger, yet the man wearing it seemed somehow sad as well, almost weary, as if he'd experienced something harrowing. His skin was pale, and his clothes dark, as if to blend in with the shadows. The hair was cropped quite short, like a soldier's haircut, and he was clean-shaven, with large hands with long, thin fingers.

But it was the man's eyes that were the strangest thing about him: they were old eyes, a fierce, steely grey, swirling with emotions like an oncoming storm, older than any eyes he'd ever seen, even Professor Dumbledore's eyes hadn't looked that old...or that weary. He could see centuries passing in that ancient gaze, whole empires of glass and thought and emotion and shadow and starlight burning and blooming like a newborn phoenix, armies slaughtering each other on battlefields in other worlds, the ground flooded inch upon inch high with blood, and explosions, and supernovas, and planets bursting into existence, people bowing and talking and flying and celebrating and dying and living all at once.

There was rage in that gaze, self-loathing unlike anything he'd ever seen anyone have, and a soul-deep sadness that welled up and hurt. There was pain in those eyes, so much pain that it hurt just to look at.

What did he see, what did he do in his life, to get eyes like that?

He gave the man a weak, watery smile, trying to break the quiet that had descended upon them. "You're not a Specialist of Arboreal Magical Oddities, are you?"

The Doctor shook his head, a smile on his face; it was crooked smile, but a smile all the same. "No. No, I'm not. I'm the Doctor, just the Doctor."

Neville decided to leave it at that. He had a feeling that the Doctor wouldn't say anything more on the subject.

Instead, he said, "So, about that tree you mentioned earlier, you said it was attacking your...ship?". The Doctor nodded, pointing beyond the greenhouse to the grounds beyond, where the blue box was vaguely visible, tangled in the center of the Whomping Willow's branches like a pirate ship in the clutches of an angry Kraken. "That's my ship, over there. The Tardis, I call her. She can travel anywhere I want to take her, but today we encountered a little problem and ended up crashing into your school's shields, and the shields blasted us into the tree, and now the tree's got my ship. I want my ship back. But I don't want to hurt the tree either, I already hit it, so I don't want to make things worse. But I don't know how to get the tree to stay still, so that I can leave without damaging it; if I leave and the tree's not frozen like a normal tree, I'm afraid I might end up causing it to hit itself instead, and those tree branches look very heavy. So, I came here, hoping to get some help. Can you fix this?"

Neville stared at the Doctor in disbelief, trying to comprehend what he'd just heard. You...you crashed into the school wards, and then the wards threw you so far that you crashed into the Whomping Willow? Well, I suppose it's not too far fetched, Hogwarts has some of the best wards in wizarding Britain, surely they're strong enough to knock things back. But I...I can't fix the Whomping Willow, it'll kill me. I need professional help for this, I need to find Professor Sprout, she can help.

"We need to find Professor Sprout, she's the Herbology Professor here. She's the best person to talk to about Hogwarts' magical plants, she's got to know how to calm it down! Lunch isn't over yet, she might still be in the Dining Hall, I can go get her and ask her to come here and talk to you, so she won't be surprised about the...ship...in the Willow. If she's surprised about it, she might tell the other teachers, and then they'll think it's dangerous and try to get rid of it, and I don't think you have another way to get around, unless you've got a broomstick..."

When the Doctor shook his head in the negative, Neville knew he was right. He headed to the table, gathering up his things and putting his books back into his school satchel. As he picked the Remembrall up off the table, the Doctor's eyes suddenly widened, gaining an interested look, as he asked curiously, "Never really looked too closely at one of those before. Do you mind if I...?"

Neville gave him a long, searching look for a moment, weighing the pros and cons of such a decision; on one hand, he already had an unfortunate habit of finding his possessions broken, stolen, or altered in some way or another, he didn't want to have to ask his Gran for yet another Remembrall. But the Doctor only seemed curious, and if it broke, he could always ask a Professor to fix it for him. "Alright," he said finally, "but please, be careful with it. It is made of glass, and it's really breakable. I already got in trouble with the last one I had."

The Doctor nodded, and took the glass ball into his hands, turning it over as he peered inside. "Say, how's this thing work?"

"It works by the smoke inside telling you if you've forgotten something. The smoke turns red if you've forgotten something, if the smoke's grey, you haven't forgotten anything," he replied, turning his attention back to packing up his satchel. A soft, "Oh dear...", from the Doctor caused him to turn around, suddenly concerned.

The Doctor was staring into the Remembrall, gazing inside with a look of uneasy fascination on his face. Holding the little glass ball in one hand, he beckoned Neville closer with the other, a strange look in his eyes as he said quietly, "Neville, how long have you had this Remembrall?".

Neville stared at him in confusion, replying, "Since this morning, I got it in the post. Why?"

"Have you...have you forgotten anything recently?"

The look on the Doctor's face was oddly concerned; he seemed desperately to want to know if the answer was yes or no. Neville had a feeling that the preferred answer was no. But he answered honestly anyways, despite the slowly growing feeling of unease creeping up his spine.

"Yeah," he said quietly, "That's why Gran sent me one in the first place, I'm always forgetting things. She thought this would help. Though, I can't really say it's much use, unfortunately, since it doesn't actually tell you what you forgot."

The Doctor looked deep into his eyes, concern and a strangely sad look on his face as he said, "Do you forget things more often, since getting this Remembrall?"

Slowly, very slowly, Neville nodded. The Doctor's shoulders sagged in some undeterminable defeat, as he turned the Remembrall in his hands, over and over, before pushing it into Neville's hand and whispering, "Neville, did you forget something this morning? Neville, look at the Remembrall. I want you to look, really look at it."

Neville didn't want to look at it. There was something wrong, something horribly, horribly wrong with his Remembrall, but he didn't want to look and find out. He didn't want to know if he'd forgotten something this time, because this time he knew, somehow, that what he'd forgotten was very important.

He looked down anyway.

The smoke inside the Remembrall turned a deep, blood red.

Uh oh.