Well, here's Year 4. Sequel to Light, Darkness and Changes, pretty much. Mostly to Darkness.
There'll be an original alien of mine in this story, just because. But not just that...

Word of warning: i might be a little evil.
Please don't hate me...
I'll explain things, as much as possible, as the story goes on. There's a reason for most of the things that happen. Most. Well, some.
Um, anyway, enjoy!

A little blue box whirled onwards through all of time. It shook, and juddered, yet it slipped through every little temporal eddy, every bit of disturbance rampant in the vortex around it.

Still, it was a bumpy ride.

It eventually materialized on a space station around some distant moon. Grinning, the Doctor, Amy and Rory left the TARDIS, off to explore.

They returned a couple of minutes later, running from a large, lethal-looking robot which they'd disturbed while gallivanting around. Panting, they ducked into the TARDIS: the robot raised two, large hands, each with an array of fine bristles on, and pressed them either side of the blue box.

Buzzing, it ran its two hands up and down the sides, brushing every speck of the exterior. Once it had finished, tapping the light at the top with what seemed to be a pleased flourish, it turned away to leave.

The Doctor looked out at it, astonished: before laughing.

It was just an automated cleaner. Nothing threatening: it just wanted to wash away dirt.

He was still laughing when the TARDIS phone rang.

The Time Lord hopped over to it, scooping it up with one hand while setting the TARDIS course with the other.

"Hello," he spoke into the phone, still grinning, "Wait a sec," he frowned, looking back down to the console. Expertly, though Amy suspected it was mostly fluke, he hit a few more buttons, sliding one thing across, and tapped an unseen word into the typewriter.

Following that, he raised the phone again, speaking properly: "Yes?"

His expression slowly decayed into one of seriousness, as the person on the other end of the phone continued. His free hand gripped the edge of the TARDIS console, tense, worried.

"Where are you?" his voice was now completely serious. Amy and Rory looked at each other, confused, and a little perturbed. It took a lot to make the Doctor act like that.

"And when?" he said, after a few seconds.

Another pause; evidently the person on the other end was responding.

"See you there," the Doctor mumbled.

Without a word to his two companions, the Time Lord began to fiddle once more with the console of the time machine. He struck a lever, grabbing onto the railing as the TARDIS shook, slowly groaning to a halt.

"Doctor?" Amy hopped forwards, trying to catch the focused Time Lord's attention: "Doctor?" she waved a hand in front of the alien's face.

"Yes," he muttered back, still distracted as he attempted to safely stabilize the box

"Where are we going?" the redhead leant forwards, frowning.

A moment of silence. The Doctor looked up at her, jumping back from the console as the wheezing of the engines fell into silence.

"Let's see!" the Time Lord gave a child-like grin, turning and sprinting out of the TARDIS doors. The two followed.

"Oh," Rory stated dully, as they left the blue box. Distinctly unimpressed.

It was Earth, by the look of it; only nowhere major. It looked, sounded, and smelt like a subway station, darkened and empty. The curved wall of white tiles opposite were just visible, in the light coming from the TARDIS interior, and a small, illuminated sphere near the ceiling.

Rory did a double take. The sphere of light didn't appear to have any particular cause; it was hanging there of its own volition, bathing the underground station in a faint, comforting glow.

Quietly, a small stray cat ambled up to them, purring slightly. Amy looked down, not quite muffling an adoring noise at the sight of it. She knelt, as if to scratch it-

And, with a step forwards, it grew into a human woman.

"Professor McGonagall," the Doctor said with an excited grin, reaching out to shake her hand.

She nodded stiffly.

"So, why are we here?" the Doctor soon sobered up. Now he spoke, sombre, determined.

"I told you on the," the teacher made an expression of distaste. Unfamiliarity with the word, "Phone." She kept her lips tight, severe.

"Amy and Rory haven't heard," the Time Lord replied, "And I could do with a bit more detail."

"You're a doctor?" McGonagall asked. Her attention was fixed on the Time Lord, and not his two companions.

"The Doctor actually," he straightened his bow tie,

"Can you help?" the teacher wasn't in the mood for any games. She continued to meet the Doctor's eyes with a frosty stare

"So I heard," the Doctor lowered his hands from his bow tie, voice dropping, "I'm going to try at least."

"Excuse me," Amy interrupted: "What's going on?"

An expression of irritation passed over McGonagall's face, as if she'd forgotten the redhead was there. Rigidly, she turned, meeting the redhead's eyes.

"Professor Dumbledore is ill," the teacher stated, simply.

O

The lights went out.

Instead of apparating to Hogwarts quickly, the Doctor had insisted he take the TARDIS. He carefully landed it, mostly by luck, in an out-of-the-way corner of the dungeons. Which was actually pretty impressive considering he'd been aiming for Dumbledore's Office, though he didn't tell anyone that.

He stepped outside, with Amy and Rory and McGonagall, looking around the dreary grey stone. A quiet few seconds passed as McGonagall adapted to her first trip in the TARDIS.

And then the doors of the TARDIS slammed shut, on their own accord. And, with one last glimpse, they saw the lights within the time machine extinguish.

"No!" the Doctor shouted suddenly, running back to the door. He flattened himself against the blue.

"Forgot to make it used to magic again?" Rory rolled his eyes; remembering earlier years.

Conventional technology didn't work in Hogwarts. They needed to adapt it to run on the magic around them; and more than once, the Doctor had needed to change the TARDIS systems so that it ran in the magic-rich area of Hogwarts.

"I did, I know I did," the Doctor was muttering, still pressed against his blue box. It gave a small, weak groan. "What's wrong?" he crooned, gently stroking a panel.

Amy and Rory shared a mildly amused glance. The Doctor seemed to have an excessive closeness to his machine, at times. He really did.

"Doctor," Rory reached out, sighing, "It's just the same thing as before. Magic….stuff," the sentence got away from him. There wasn't really an easy way to say it.

"I'm sure I fixed it," the Doctor mumbled, stepping away slowly, frowning, "I'm sure."

"Evidently not," Amy replied, with a great exhalation, literally dragging the Doctor away from the TARDIS.

The Doctor had already stepped away from the sealed TARDIS however; trusting in his machine's capacity to recover. Dumbledore's apparent illness was a great deal more pressing.

They hastily moved through the halls and corridors of Hogwarts School. The year had just started; and plenty of students could be seen milling around, especially new ones, some dressed in dainty blue, some in tough fur and darkened clothing.

"The Triwizard Tournament," McGonagall said, by way of explanation, as she lead them through Hogwarts. "The students of two more wizarding schools, Durmstrang and Beauxbatons, are staying at Hogwarts to take part."

The Doctor wasn't listening. Too distracted: his encyclopaedic mind was running through every possible illness Dumbledore could have contracted, and their respective cures.

Time kept diverging around Hogwarts. Things kept changing; in every single year so far. And now Dumbledore had fallen sick, and something strange had possibly happened to the TARDIS. He didn't dwell on the latter, hoping otherwise, but he still remembered.

Was something interfering? Someone?

They passed the Great Hall. The goblet of fire flared up as they moved past; a Beauxbatons student dropping her name into the goblet. A group of younger students watched from the side, envious of those old enough to enter.

Quite some minutes later, McGonagall reached the gargoyle to Dumbledore's Office. The Doctor paced, impatient, behind her, waiting for her to speak the password, and lower the statue.

Eventually, they were within the headmaster's office. It instantly looked different; darker.

A curtain was drawn across the back window; the only light came from Fawkes. The phoenix was standing on its normal perch; head drooped, feathers blackened. It was clearly upset; a tear beaded in the corner of its eye, and the feathers around its eyes were damp.

Phoenix tears were supposed to heal. There was something off with this illness, if Fawkes had not cured it.

Dumbledore's wand lay on his desk; though the headmaster himself could not be seen. McGonagall silently lead them through the darkened room. Her solemn expression could clearly be seen in the phoenix light.

"Here," she said, closing her eyes. Her tone and gesturing hand were quivering.

A soft murmur came from where she was pointing; behind an obscure bookcase, one that stood near the back of the office. Dumbledore couldn't clearly be seen; only his vague silhouette through the books. He was sitting or kneeling.

The Doctor gestured to the other three, not speaking, placing a finger on his lips. Then, carefully, he stepped around, quiet. Frowning, he moved closing to the headmaster.

Dumbledore was sitting on the floor, surrounded by a pile of fallen books. His robes were loosely draped over his thin body, and a little food was smudged on his chin. He wasn't moving.

Apparently the teachers were feeding him, giving him drink and sustenance. There was nothing that the Doctor could see, physically wrong with him. He just wasn't moving; not at all.

Dumbledore stared forward, not reacting to the Doctor's approach, not looking at the Time Lord.

"Hello?" the Doctor said softly, tentative, frowning.

Dumbledore turned, eyes wide, staring. Unblinking. The only movement was in his neck; the headmaster stayed completely still after the brief, small action. Blue eyes were wide.

"Hello," Dumbledore rasped, the word coming from seemingly reluctant lips.

"Are you ok, Albus?" the Doctor leant closer, reaching out slowly to touch the headmaster's old cheek.

A moment of silence. The Doctor's hand was just centimetres from his head, when Dumbledore opened his mouth, speaking once more.

"Are you ok, Albus?" he echoed the Doctor's words, words little more than a croak, eyes wide in the darkness.

The Doctor tensed, pulling his hand back: "It can't be," he murmured, weakly

"It can't be," Dumbledore echoed, still rasping. Voice almost mocking.

The Time Lord stepped back, breathing heavily. Almost afraid: at the very least, profoundly shocked. In his mind, several possibilities ran.

And one of them was guilt. Was this his fault? It was conceivable. Easily possible. This creature- There was no possible way it should be on Earth, let alone in this century.

"Everyone, out," the Doctor said clearly, urgent. The others looked at him, surprised, yet the Time Lord continued, more forceful this time: "We'll talk outside. Out, now!"

As soon as he finished speaking, Dumbledore again began to speak. His slow, whispered words went unheard by the others; they were already exiting, spurred on by the Doctor's urgency.

Everyone, out. We'll talk outside. The headmaster shook, giving what could only be described as the semblance of a smile. His blue eyes were wide, tortured. Out, now!