Bold in the story is taken from Harry Potter and the Prisoner of Azkaban.

It is with slight shame that I admit I forgot there was to be excitement after the feast on Halloween. I had planned to stay awake for a few more hours, and had changed out of my robes form the feast. I was in plain grey sleep pants and a black t-shirt. When the ghosts came through alerting all teachers to report to the Great Hall it hit me, and I started cursing creatively while pulling on my converse. The Fat Friar admonished me for my language, but I ignored him, sending him on to his next target.

When I made it to the Great Hall I had my wand in hand, hair pulled up into a messy bun, and an irritated scowl on my face. Several of the students were staring, and I put that down to realizing that yes, teachers are people too, and they also dress like normal ones from time to time.

"What's happening, Minerva?"

"Sirius Black, that's what!"

"Has he been sighted?"

"He attacked the portrait guarding Gryffindor common room, we think he's still in the castle somewhere."

I glanced around at the students, back subconsciously straightening, going into my 'Doctor advising mode'.

"And you decided to put them all in one place?"

"Easier to protect, Albus said."

I glanced over at where the Headmaster was speaking with the Head Boy and Girl in lowered voices and shrugged.

"I suppose. I would have thought that with only one assailant it would be a tricky gamble making it one single target that was stupidly easy to find, and then trapping that target with no means of escape. But then again, this is one man, unarmed, and with no back up approaching. He did attend Hogwarts so he would have some idea of where the entrances to the different common rooms are, and some knowledge of the layout of the castle. I'm at a distinct disadvantage in this search, I know the castle about as well as the first years, if even that. Am I to be left to guard the students then?"

An amused voice from behind us had Minerva jumping and my wand twitching in my hand.

"Brilliant as always, Marissa. Indeed I thought you would be the perfect staff member to leave behind with the students."

The Headmaster turned to the kids,

"The teachers and I need to conduct a thorough search of the castle, I'm afraid that, for your own safety, you will have to spend the night here. I want the prefects to stand guard over the entrances to the hall and I am leaving Professor Swift in charge, with the Head Boy and Girl. Any disturbance should be reported to me immediately. Send word with one of the ghosts. Should the dementors attempt entrance...well, I've heard you're capable of a full patronus, Marissa, send them on their way through whatever means possible."

I nodded, not bothering to question how he knew, and he nodded.

He swept his wand over the hall and the sleeping bags appeared.

Of course the night went without incident, Sirius wasn't after anything we had in here. When Dumbledore came into the hall to speak with us I wandered over to where Percy was, only steps away from the Golden Trio.

"Any sign of him, Professor?" asked Percy in a whisper.

"No. All well here?"

He was looking at me rather than Percy, and I felt a bit bad for stealing Percy's one important moment.

"Perfectly fine. A few freaked out First Years, but nothing chocolate couldn't fix."

"Good."

He had gone back to talking to Percy so I took a few steps away, glancing here and there at the students. I caught Harry listening in when Snape was speaking and he looked terrified. I winked at him and turned away to pay attention just as Dumbledore was swearing no Dementors would enter his castle.

I murmured,

"Damn straight."

That got me an amused look from him, and a slight head shake.

"Marissa, perhaps you should head back to your rooms. The other professors can take over from here."

I raised an eyebrow at him, crossing my arms in slight challenge. Crossing the arms lead me to see my scars on full display and I remembered why I wore the long sleeved robes at all times. I cleared my throat, uncrossing my arms and clasping my hands behind me.

"That would probably be best."

"One last thing, Marissa dear. How far did you get on that project with the portrait of that friend of yours?"

I turned to him, brow furrowed, not sure where this was going.

"I got the runes outlined, and some layered enchantments drafted. But I'm still at a loss for a second caster."

"Report to my office in the morning with the materials, I may have a solution for both of our problems."

Well, that sounds ominous.

I nodded to him,

"Yessir."

I dragged my fingers down my arms, lengthening the sleeves in a wandless transfiguration. It wouldn't last long, but I would make it back to my rooms at least.

The next morning I dressed in my skinny jeans, converse, and a long sleeved shirt, blue this time. It had taken months of charm work to get just the right shade of TARDIS blue, but I had managed eventually. The papers where piled into my hands, and I could barely see around it. I reached the Gargoyle outside the Headmaster's office at just after nine in the morning.

"Blood pops."

I rode the moving stairs like an escalator, enjoying the brief return of a modern luxury.

When I reached the top the door was slightly ajar, I knocked on the frame for half a second before pushing through, pausing in surprise at the scene before me. Dumbledore was behind his desk, the pensieve set out on top of it, with Snape standing off to the side, looking sullen.

"Ah, Marissa, wonderful timing. Lemon drop?"

I entered the room, walking swiftly to the desk and setting the papers down on one corner, taking one of the proffered sweets.

"Thank you."

He beamed at me, probably for being the only one to actually try a lemon drop.

"Now, down to business. This person you wanted to create a painting of, would you mind answering some questions about them? Just, to indulge an old man for a few minutes."

I nodded and he continued.

"Now, why don't you describe them for me, what did they do for a living?"

I shifted my weight slightly, staring out the window behind him, thinking on it.

"Well, he was the Doctor. He traveled, we traveled, that is. Wherever we ended up he leant a helping hand to those in need. He was always getting us into trouble, but he always got us back out again. He saved my life more times than I can count, and he was the smartest person I've ever known. He could be rude at times, when someone did something cruel or unusually wicked, and he would often lie in attempts to protect us from the truth. He was by no means perfect, but he was brilliant in his own way."
Dumbledore eyed me for a second, eyes twinkling like always. Finally he sat back in his chair.
"We have recently run into a problem with the portraits in the castle. None of a...satisfactory nature are willing to take up the mantle of guard for Gryffindor Tower. Would this friend of yours be willing to take the risk, should we bring him to painting form?"
Are you joking? Guard Gryffindor Tower from beyond the grave? He'd beg for this under different circumstances.

I gave him a half-smile,

"Oh, I think he'd be very willing."

The Headmaster nodded, smiling brightly,

"Perfect! Of course this is only temporary, you shall have your friend back soon enough. Now, to be on with the how of it all. There are two ways to share the memory and gain a second caster, as you are well aware. You have before the means for both. You may choose whatever route you so wish. Keep in mind that with the pensieve memories the likeness to the actual man may be slightly more lacking than if legilimency had been used. However, I am aware that most are unwilling to have their minds riffled through, so it is always an option."
I darted my eyes over to Snape, who was trying his best to blend into a shadowy corner.

"You can read minds?" I grinned, "Oh, the Hufflepuffs were right then. They knew there was no way you were just that good at sensing trouble making."
He huffed,

"I have never delved into the mind of a student for such trifle matters."

I shrugged,

"If you say so, then."

I examined his body language for a second, trying to figure out exactly how he felt about all of this.

"What about you then, how do you feel about having to use legilimency for this?"
"...what?"
I rolled my eyes, leaning slightly against the desk.
"Well, going through some random persons mind can't be fun, and the casting of the spells for the portrait would be draining at best, even with both of us. There are dementors running amok, and a mass murderer on the loose, not a good time to be a bit on the drained side. Then you have to take into account that you'll actually have to be in my mind, which isn't a pleasant place, I assure you. So, if you don't actually want to do it then I'm fine using a pensieve."

He blinked at me slowly, and the Headmaster was beaming. I had a feeling I had just proved him right about something.

"See Severus, I told you she wouldn't mind if you backed out now."

Snape glowered at him before turning a scowl on me.

"I will have no trouble with either the memory or the spell, Swift."

Oh, last names, is it? Then he was most likely doing this because Dumbledore asked him to, or because he figured having me owe him one would be good in the long run. Very Slytherin way of thinking.

I grinned,

"Alright then, what's first, Headmaster?"
Setting up the runes for the spell, and getting the canvas in place took almost an hour. The canvas had to be susceptible to spell work in that it could be enlarged and used as a doorway, and then shrunk back to a more manageable size once it's stint as guardian was done. The canvas, blank and only 3 feet tall, one and a half wide at the moment, sat on an easel in the middle of an array of runes. There were 7 concentric circles of runes, the outer two done in ink, the next four done in black paint, and the inner one done in my own blood, since I was the primary caster.

Snape and I stood in the gaps between the last ink circle and the first paint circle. He turned to me, wand out and at his side.

"You are unlikely to have been versed in Occlumency, from before you lost your memory. However, just in case, I would like you to keep in mind that fighting me would only be painful for the both of us. Now, concentrate on the memory. The memory of the man you wish to be in the painting, exactly as you wish him to be captured forever. If he is furious in the memory, then he shall have anger as his foremost emotion even in the portrait. Try to keep in mind where you wish him to be captured as well."

I nodded, remembering the research I had done into it. I already had the memory and location in mind. Snape would likely be slightly confused as the hum that could always be heard in the TARDIS library, but he would get over it. I wasn't having the Doctor separated from his blue box just for the sake of a cranky potions professor's curiosity.

"Very well then. Legilimens!"

The moment the spell hit me I knew my experience with psychic races would help here. It was much the same feeling as when they would slip through my mind. It was equally as easy to direct him to the memory. I saw it clearly, the Doctor, sitting in his favorite chair, a deep blue wingback with fluffy pillows scattered around. His brown hair was flopping into his eyes and he brushed it back absentmindedly, reading the book in front of him intently. The lights from the TARDIS gleamed off that brilliant red bowtie, casting slight shadows over where his tweed jacket was thrown over the table nearby. Shelves upon shelves of books extended as far as the eye could see, and beyond. Gleaming carvings of Circular Gallifreyan were scattered along the silver walls. A fez, matching the red bowtie, was sitting on the mantle to the fireplace, slightly dented still from our last adventure. At the Doctors elbow was a fresh plate of Fish fingers, with a small bowl of custard beside a large mug of tea.

The memory slipped away rather abruptly, and a large hand caught my upper arm before I could fall over. I looked up at Snape and his face was blank. Just like we had discussed before hand the both of us straightened without a word, turning to the easel and pointing our wands.

Both parts of the spell were nonverbal, and our wands shot jets of color at the blank canvas, color bleeding in. The painting formed over the course of a few minutes, heartbreakingly lifelike, and completely still. The moment the first spell was completed we started the wand motions for the next one, launching into the next part of the enchantment. This was the draining part, the portion of the spell that gave life and personality to the portrait.

I woke up on the floor to the sound of voices, and felt a hand on my shoulder. I opened my eyes instantly, flinching at the light. I hauled myself up to a sitting position, eyes automatically going to the canvas. The Doctor was there, grinning widely.

"Mara you brilliant girl you! Hogwarts, you're at Hogwarts! How'd you manage that?"
I grinned right back,

"Good to see you too, Doctor. It's a long story, I'm afraid. I'll tell you later. For now, how do you feel about guarding a certain tower?"
It was lunchtime, and most of the students were in the Great Hall while we were putting the Doctor's portrait into place. He was running around, gabbering excitedly about everything, waving his sonic around uselessly. No one had commented, probably assuming it was his wand. He moved it fast enough, you couldn't tell the light wasn't the spark of a spell. Dumbledore levitated him for us, all the way to the tower, since neither Snape nor I had the energy for it. A pain in me I hadn't really noticed was there eased with the chatter, the familiar voice, the antics, all of it. This incarnation of the Doctor was the one most recently...deceased, in a way. And I'd never had a proper goodbye.

There were no students hanging around when we moved the Fat Lady's empty frame out of the way, fixing the Doctor in place. Dumbledore stepped back from him, eyeing the placement.

"Very nice. Now, Doctor…?"
"Just, the Doctor."

"Right, then, Doctor. What would you like to set the password as? I need to be kept informed of this. You can travel through the frames of other portraits, should you have need to, and informing me of a change in password is one of those times when doing so might be necessary."

The Doctor didn't hesitate.

"Norwegian Ridgeback!"

I snorted,

"Dragons, of course you chose a dragon on your first go."

He stuck his tongue out at me.

"I could have done worse."

I rolled my eyes playfully.

"Yes, you could have given them Raxacoricofallapatorius on their first go, the poor dears. At least try to keep in pronounceable."

The first student to arrive back at the tower, was of course, the Head Boy.

Dumbledore and Snape had long since left for lunch, Dumbledore to make the announcement about the change in portrait so the Gryffindors wouldn't lose their minds, and Snape to build back up his energy. He had recommended I do the same, but wasn't surprised when I stayed to chat with the Doctor.

"Hello Professor, is this our new guardian?"
The Doctor's jaw dropped, and he whirled around to look at me.

"Professor? You're a teacher? Who in their right mind made that happen?!"

I shrugged,

"I told the Headmaster it was a bad idea, but here we are anyway."

I turned to Percy,

"This is the Doctor. He's a new portrait, an old friend of mine. Do be kind to him."

Percy was nodding gravely, but the Twins were behind him and examining the Doctor, who was looking them over as well, barely hiding his excitement.

"A friend of yours, Professor?"
"From America?"

The Doctor chose that moment to speak up,

"Me? American? Of course not, though I did have that incident with Marilyn Monroe…."
I sighed,

"Doctor, do try to keep it PG. Anyway kids, you have fun. I'm going to go eat a horse or something."
A plaintive cry of 'Not Susan!' followed me down the hall and I rolled my eyes, still grinning wildly. The Doctor was back. Sort of. Good enough for me.

~TimeLordOfPie